C1-Symmetric Zirconium Complexes of [ONNOâ²]-Type Salan Ligands

Organometallics 2009, 28, 1391–1405

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C1-Symmetric Zirconium Complexes of [ONNO′]-Type Salan Ligands: Accurate Control of Catalyst Activity, Isospecificity, and Molecular Weight in 1-Hexene Polymerization Ad Cohen, Jacob Kopilov, Israel Goldberg, and Moshe Kol* School of Chemistry, Raymond and BeVerly Sackler Faculty of Exact Sciences, Tel AViV UniVersity, Ramat AViV, Tel AViV 69978, Israel ReceiVed NoVember 3, 2008

New Salan ligand precursors that include differently substituted phenol arms were prepared by a twostep synthetic pathway. The ligand precursors included activity-enhancing electron-withdrawing groups on one phenol ring, stereodirecting bulky groups on the other phenol ring, and either diaminoethane or trans-1,2-diaminocyclohexane as the diamine skeleton. Reacting the ligand precursors with either tetra(O-tert-Bu)zirconium or tetrabenzylzirconium led to [(Salan)ZrX2]-type complexes (X ) O-tert-Bu, Bn) of octahedral geometry and C1-symmetry as single stereoisomers in all cases. Crystal structure studies indicated that the fac-fac isomers had formed. The chiral Salan ligands were found to wrap in a fully diastereoselective manner. All the dibenzylzirconium complexes polymerized 1-hexene upon activation with tris(pentafluorophenl)borane. The electron-withdrawing ability of the substituents was the dominant factor in enhancing the catalysts’ activity; thus Lig2ZrBn2, featuring a dichlorophenolate arm and a ditert-Bu-phenolate arm, led to an activity of 1300 g mmol-1 h-1, whereas Lig4ZrBn2, featuring a diiodophenolate arm and a di-tert-Bu-phenolate arm, led to an activity of 180 g mmol-1 h-1. Pentad analysis showed that despite the catalysts’ C1-symmetry, hemiisotactic polymers had not formed. Instead, isotactic polymers were produced, the extent of isotacticity depending on the bulk of substituents on both rings, and independent of the rigidity of the diamine skeleton; thus Lig2ZrBn2 led to poly(1-hexene) of [mmmm] ) 54%, and Lig4ZrBn2 led to poly(1-hexene) of [mmmm] ) 76%. The Salan complexes of the more rigid diaminocyclohexane skeleton were less active, their typical activities being ca. 55 g mmol-1 h-1, and led to polymers of higher molecular weights. Unraveling these trends enabled the development of a catalystsLig10ZrBn2shaving a high activity of 300 g mmol-1 h-1 and leading to high a molecular weight polymer of almost perfect isotacticity of [mmmm] ) 95%. Introduction The development of homogeneous catalysts for stereospecific polymerization of R-olefins is an ongoing challenge in organometallic chemistry.1,2 The intensive study of the group 4 metallocene systems led to the introduction of numerous active catalysts of various types and degrees of stereocontrol and to the establishment of several rules regarding the effect of the catalyst structure on the polymer microstructure.3 Some rules relevant to the current work are the following: First, these socalled “single-site” catalysts are in fact “double-site” catalysts,4 the two coordination sites being occupied by a growing polymeryl chain and a coordinated monomer unit that exchange positions after every migratory insertion event, as outlined in Scheme 1. Second, there is a close correlation between the * Corresponding author. E-mail: [email protected]. (1) StereoselectiVe Polymerization with Single-Site Catalysts; Baugh, L. S.;, Canich, J.-A. M., Eds.; CRC Press: Boca Raton, FL, 2008. (2) Coates, G. W. Chem. ReV. 2000, 100, 1223. (3) For several review articles on stereospecific polymerization by metallocene catalysts, see: (a) Resconi, L.; Cavallo, L.; Fait, A.; Piemontesi, F. Chem. ReV. 2000, 100, 1253. (b) Alt, H. G.; Ko¨ppl, A. Chem. ReV. 2000, 100, 1205. (c) Bochmann, M. J. Chem. Soc., Dalton Trans. 1996, 255. (d) Brintzinger, H. H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.; Waymouth, R. M. Angew. Chem., Int. Ed. 1995, 34, 1143. (4) The two terms correspond to two different aspects: The term “singlesite catalyst” implies that in contrast to heterogeneous polymerization catalysts all the metal centers in homogeneous catalysts reside in identical environments. The term “double site” means that polymerization catalysis requires the presence of two coordination sites on the metal.

Scheme 1. “Double-Site” Polymerization Mechanisma

a After two consecutive insertions, the original geometry is restored and the polymeryl chain (P) is longer by two repeat units.

symmetry of the catalyst and the tacticity of the resulting polymer, as originally realized by Ewen.5 In particular, C2symmetric ansa-metallocenes in which the two sites are homotopic may distinguish between the two enantiotopic faces of an incoming olefin and lead to isotactic polymers. Third, the stereoregularity is not induced by direct interactions between the catalyst and the incoming olefin. Rather, the growing polymeryl chain occupies a less hindered “quadrant”, and the olefin coordinates to the metal so that its side-chain points away from the polymeryl group.6 Fourth, for stereorigid C1-symmetric catalysts the type of tacticity may vary depending on both the (5) (a) Ewen, J. A. J. Am. Chem. Soc. 1984, 106, 6355. (b) Ewen, J. A. J. Mol. Catal. A: Chem. 1998, 128, 103. (6) Busico, V.; Cipullo, R. Prog. Polym. Sci. 2001, 26, 443.

10.1021/om801058w CCC: $40.75  2009 American Chemical Society Publication on Web 02/09/2009

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monomer face preference in each of the two diastereotopic sites and the possible hopping of the polymeryl chain between sites, referred to as “site epimerization” or “chain back-skip”. Thus, a hemiisotactic polymer is produced by C1-symmetric catalysts in which one site is face-selective while the other is not, combined with negligible site epimerization.7,8 Notably, in these ansa-metallocene catalysts the nondirecting site is the more sterically congested one. Further increase of the congestion at that site leads to site epimerization of the polymeryl group after every insertion to the face-selective site, yielding an isotactic polymer.9-12 In recent years there is a growing interest in catalysts of the non-metallocene and cyclopentadienyl-free types with the goal of discovering new activity modes and introducing new types of polymers.13 Among these, the group 4 complexes of Salan ligands, first introduced in the year 2000,14 bear the closest relationship to Brintzinger’s C2-symmetric ansa-metallocenes.15 Salans are tetradentate dianionic [ONNO]-type ligands that prefer to wrap around group 4 metals in a fac-fac mode,16 yielding octahedral complexes of C2-symmetry in which the two labile groups are in cis geometry.17-20 Dibenzylzirconium complexes of Salans bearing phenolates with bulky alkyl groups (7) (a) Ewen, J. A.; Elder, M. J.; Jones, R. L.; Haspelagh, L.; Atwood, J. L.; Bott, S. G.; Robinson, K. Makromol. Chem., Macromol. Symp 1991, 48-9, 253. (b) Guerra, G.; Cavallo, L.; Moscardi, G.; Vacatello, M.; Corradini, P. Macromolecules 1996, 29, 4834. (8) For the 13C NMR analysis of hemiisotactic polypropene prepared from 2-methylpentadiene, see: (a) Farina, M.; Di Silvestro, G.; Sozzani, P. Macromolecules 1982, 15, 1451. (b) Di Silvestro, G.; Sozzani, P.; Savere´, B.; Farina, M. Macromolecules 1985, 18, 928. (9) For recent reviews on stereoregular polymerization with C1symmetric metallocenes, see: (a) Price, C. J.; Irwin, L. J.; Aubry, D. A.; Miller, S. A. pp 37-82, in ref 1. (b) Razavi, A.; Thewalt, U. Coord. Chem. ReV. 2006, 250, 155. (10) For isospecific polymerization by C1-symmetric catalysts invoking the alternating mechanism, see: Miller, S. A.; Bercaw, J. E. Organometallics 2006, 25, 3576. (11) For hemiisotactic-isotactic blocks, see: Miller, S. A.; Bercaw, J. E. Organometallics 2002, 21, 934. (12) For a mechanistic proposal of isospecifc polymerization by C1symmetric metallocenes not invoking site-epimerization, see: van der Leek, Y.; Angermund, K.; Reffke, M.; Kleinschmidt, R.; Goretzki, R.; Fink, G. Chem.-Eur. J. 1997, 3, 585. (13) (a) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem., Int. Ed. 1999, 38, 428. (b) Gibson, V. C.; Spitzmesser, S. K. Chem. ReV. 2003, 103, 283. (14) Tshuva, E. Y.; Goldberg, I.; Kol, M. J. Am. Chem. Soc. 2000, 122, 10706. (15) Wild, F. R. W. P.; Zsolani, L.; Huttner, G.; Brintzinger, H. H. J. Oragnomet. Chem. 1982, 232, 233. (16) We prefer the fac-fac, mer-mer, and fac-mer (mer-fac) terminology over the respective cis-R, trans, and cis-β terminology, for describing the wrapping modes of linear tetradentate ligands around octahedral metal centers, since they relate to the chelating ligand and not to the remaining coordination sites, give a better notion of the symmetry of the complex, and are more informative. See: (a) Garcı´a-Zarracino, R.; Ramos-Quin˜ones, J.; Ho¨pfl, H. J. Organomet. Chem. 2002, 664, 188. (b) Yeori, A.; Gendler, S.; Groysman, S.; Goldberg, I.; Kol, M. Inorg. Chem. Commun. 2004, 7, 280. (17) Bis(phenoxy-imine) catalysts are structurally related to the Salans, but have led to highly active or syndiospecific polymerizations. For several reviews, see: (a) Suzuki, Y.; Terano, H.; Fujita, T. Bull. Chem. Soc. Jpn. 2003, 76, 1493. (b) Matsugi, T.; Fujita, T. Chem. Soc. ReV. 2008, 37, 1264. In contrast, bis(phenoxy-ketimine) complexes led to isospecific polymerization: (c) Edson, J. B.; Wang, Z.; Kramer, E. J.; Coates, G. W. J. Am. Chem. Soc. 2008, 130, 4968. (18) For complexes of Salen ligands that wrap analogously and lead to isotactic polymers of high olefins, see: Strianese, M.; Lamberti, M.; Mazzeo, M.; Pellecchia, C. Macromol. Chem. Phys. 2008, 209, 585. (19) For Ti complexes of related [OSSO]-type ligands that led to isotactic styrene polymerization, see: Capacchione, C.; Proto, A.; Ebeling, H.; Mu¨lhaupt, R. Moller, K.; Spaniol, T. P.; Okuda, J. J. Am. Chem. Soc. 2003, 125, 4964. (20) For flexible zirconium complexes of [OSSO]-type ligands, see: Cohen, A.; Yeori, A.; Goldberg, I.; Kol, M. Inorg. Chem. 2007, 46, 8114.

Cohen et al.

Figure 1. C1-Symmetric ansa-metallocene precatalysts leading to hemiisotactic (left) or isotactic polypropene.

in the ortho positions were found to yield highly isotactic poly(1-hexene) upon activation with tris(pentafluorophenyl)borane, while their activity was low.21 In contrast, dibenzylzirconium complexes of Salans bearing electron-withdrawing halo groups led to stereoirregular polymers of low molecular weight, while their activity was considerably higher.22,23 A further development involved the changing of the ligand backbone from diaminoethane to trans-1,2-diaminocyclohexane,24 yielding enantiomerically pure zirconium complexes,25 enabling chiral cyclopolymerization26 and asymmetric catalysis.24,27,28 All these Salan ligands featured identical phenol groups, so the two sites of their resulting complexes were homotopic. Salan ligands that include differently substituted phenol arms (i.e., [ONNO′]-type Salans) should lead to C1-symmetric complexes having two diastereotopic sites. In the work described herein, we set out to synthesize hybrid Salan ligands, namely, ligands that include electron-withdrawing halo substituents on one of the phenolate arms and bulky alkyl substituents on the other arm, and investigate the structure and activity of their resulting zirconium complexes. Our goals were gaining further insight into the mode of activity of Salan catalysts and possibly developing catalysts that will combine high activities and stereospecificities.

Results Ligand Design and Synthesis. The “quadrant representation” is a schematic graphic description of the directing ability of a given catalyst emphasizing symmetry and steric interactions.29 With the rear hemisphere of the catalyst being blocked by the chelating ligand environment, the available space for monomer coordination and polymeryl growth is divided into four quadrants. Figure 2 illustrates modified quadrant representations of two C2-symmetric Salan complexes side-by-side with their molecular structures extracted from their X-ray structures. The labile positions reside on the equatorial wedges, and the degree of steric hindrance is represented by the size of the spheres (21) For propylene homopolymerization and ethylene-propylene blockcopolymerization employing this type of zirconium-Salan complexes, see: (a) Busico, V.; Cipullo, R.; Ronca, S.; Budzelaar, P. H. M. Macromol. Rapid Commun. 2001, 22, 1405. (b) Busico, V.; Cipullo, R.; Friederichs, N.; Ronca, S.; Togrou, M. Macromolecules 2003, 36, 3806. (c) Busico, V.; Cipullo, R.; Pellecchia, R.; Ronca, S.; Roviello, G.; Talarico, G. Proc. Natl. Acad. Sci. 2006, 103, 15321. (22) Segal, S.; Goldberg, I.; Kol, M. Organometallics 2005, 24, 200. (23) These catalysts were highly active in the isospecific polymerization of the bulky monomer vinylcyclohexane: Segal, S.; Yeori, A.; Shuster, M.; Rosenberg, Y.; Kol, M. Macromolecules 2008, 41, 1612. (24) Yeori, A.; Groysman, S.; Goldberg, I.; Kol, M. Inorg. Chem. 2005, 44, 4466. (25) Yeori, A.; Goldberg, I.; Shuster, M.; Kol, M. J. Am. Chem. Soc. 2006, 128, 13062. (26) Yeori, A.; Goldberg, I.; Kol, M. Macromolecules 2007, 40, 8521. (27) For application of chiral Salan complexes in asymmetric catalysis, see: (a) Matsumoto, K.; Saito, B.; Katsuki, T. Chem. Commun. 2007, 3619. (28) For related chiral fluorous dialkoxy-diamine ligands that wrapped around zirconium non-diastereoselectively and gave poly(1-hexene) of medium isotacticity, see: Kirillov, E.; Lavanat, L.; Thomas, C.; Roisnel, T.; Chi, Y.; Carpentier, J.-F. Chem.-Eur. J. 2007, 13, 923. (29) Corradini, P.; Guerra, G.; Cavallo, L. Acc. Chem. Res. 2004, 37, 231.

C1-Symmetric Zirconium Salan Polymerization Catalysts

Organometallics, Vol. 28, No. 5, 2009 1393 Scheme 2. Prototypical Nonsymmetric Salans, Their Wrapping Mode, and Their Quadrant Representation

Figure 2. Quadrant representation corresponding to structures of C2-symmetric octahedral complexes of typical bulky (top) and nonbulky Salan ligands.

occupying the individual quadrants. The presence of bulky tertbutyl ortho substituents (large solid spheres in Figure 2, top) effectively blocks the top-left and bottom-right quadrants, causing a polymeryl group in one of the homotopic positions to orient accordingly. Consequently, isotactic polymers are produced. Changing the phenolate substituents to the electronwithdrawing chloro groups (small hollow spheres in Figure 2, bottom) diminishes the steric interaction with the polymeryl group to the extent that stereoirregular polymers are produced. In a recent preliminary work, we described the synthesis of two prototypical [ONNO′]-type Salan ligand precursors both including a 2,4-dichlorophenol arm and a 2,4-di-tert-butyl phenol arm and based on either 1,2-diaminoethane (Lig2H2) or trans-1,2-diaminocyclohexane (Lig7H2) cores.30 These led to well-defined octahedral complexes of C1-symmetry of the type {[ONNO′]ZrX2} (X ) O-tert-Bu, Bn), in which the Salan ligands were found to wrap in the desired fac-fac mode (Scheme 2). The dibenzyl complexes led to 1-hexene polymerization catalysts upon activation with tris(pentafluorophenyl)borane, yielding mildly isotactic poly(1-hexene) ([mmmm] ) ca. 0.50).31 To gain insight into the effects of both of the diastereotopic sites on catalyst activity and polymer tacticity, gradual steric changes were introduced independently in both rings, as illustrated schematically in Figure 3. One series of ligands was designed to include tert-Bu groups on one of the phenolate rings and electron-poor halo groups of various sizes on the other ring (horizontal direction in Figure 3). These are [o-H, p-Cl], [o-Cl, p-Cl], [o-Br, p-Br], and [o-I, p-I]. The other series included chloro groups on one of phenolate rings and alkyl groups of various sizes on the other ring (vertical direction in Figure 3). (30) Cohen, A.; Yeori, A.; Kopilov, J.; Goldberg, I.; Kol, M. Chem. Commun. 2008, 2149. (31) C1-Symmetric titanium complexes including two different phenoxyimine ligands exhibited enhanced polymerization activity: Mason, A. F.; Coates, G. W. J. Am. Chem. Soc. 2004, 126, 10798.

These are [o-tert-Bu, p-tert-Bu], [o-1-Adamantyl, p-Me], and [o-trityl, p-Me]. To evaluate the effect of rigidifying the diamine skeleton and validate the tacticity data, we also synthesized several such ligands built around the trans-1,2-diaminocyclohexane skeleton. An additional ligand included o-1-adamantyl phenolate and diiodo phenolate based on the diaminoethane skeleton (Vide infra). The specific ligands are listed in Chart 1. The synthesis of the symmetric [ONNO]-type Salan ligand precursors was straightforward. Most ligand precursors could be synthesized by a single-step Mannich condensation between the disecondary amine, formaldehyde, and the substituted phenol.32,33 Alternatively, these ligand precursors could be prepared by condensation of the diprimary amine with the corresponding salicylaldehyde followed by sodium borohydride reduction and (if required) further N-alkylation. However, these methods were not applicable for the synthesis of the nonsymmetric [ONNO′]-type Salan ligand precursors and usually led to 1:1 mixtures of the two symmetric Salans. The method we developed relied on condensation of the disecondary amine with the corresponding salicylaldehyde (to form the cyclic aminal) followed by sodium borohydride reduction to form the monophenolate intermediate selectively. This was reacted with the bromomethyl derivative of a differently substituted phenol to yield the desired Salan ligand precursor, as outlined in Scheme 3 for Lig1H2. The required bromomethyl derivatives were synthesized by bromomethylation of the corresponding phenol (See the Experimental Section). (32) Tshuva, E. Y.; Gendeziuk, N.; Kol, M. Tetrahedron Lett. 2001, 42, 6405. (33) For a recent synthesis of Salans by Mannich condensation employing microwave irradiation, see: Kerton, F. M.; Holloway, S.; Power, A.; Soper, R. G.; Sheridan, K.; Lynam, J. M.; Whitwood, A. C.; Willans, C. E. Can. J. Chem. 2008, 86, 435.


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Figure 3. Quadrant representation of the Salan complexes employed in the current work featuring substituents of different bulk on both phenol rings. Chart 1. Nonsymmetric Salan Ligand Precursors Employed in the Current Work

Synthesis of Zirconium Complexes and Crystallographic Studies. Two types of zirconium Salan complexes were prepared from the above ligand precursors: {[ONNO′]-Zr(O-tert-Bu)2} and {[ONNO′]-ZrBn2}. They were prepared by alcohol elimination and toluene elimination reactions at room temperature between the ligand precursors and Zr(O-tert-Bu)4 or ZrBn4, respectively. The {[ONNO′]-Zr(O-tert-Bu)2}-type complexes were obtained in very high to quantitative yields as white crystalline solids. 1H NMR spectra indicated that all complexes had formed as single isomers of C1-symmetry. Crystals of complexes Lig2Zr(O-tert-Bu)2 and Lig10Zr(O-tert-Bu)2 based on the diaminoethane skeleton and Lig7Zr(O-tert-Bu)2, Lig8Zr(Otert-Bu)2, and Lig9Zr(O-tert-Bu)2 based on the trans-1,2diaminocyclohexane skeleton suitable for X-ray diffraction analysis were grown from suitable solutions, and their structures were solved. Stick representations of these structures are outlined in Figure 4, and selected bond lengths and angles are listed in Table 1. The structures exhibit very high consistency in terms of ligand wrapping mode. As may be anticipated from the structures of the symmetric complexes, all the nonsymmetric Salan ligands wrap in a fac-fac mode around the octahedral zirconium centers,

leading to a cis relationship between the two O-tert-Bu groups. Another important structural feature is that all the complexes of the chiral Salans formed as single diastereoisomers of predetermined chirality at the metal according to the previously established rule (an (R,R)-chiral Salan wraps in a ∆-screw sense and (S,S)-chiral Salan wraps in a Λ-screw sense around zirconium). Notably, the almost identical O-Zr-O angle between the two O-tert-Bu groups (107-108°) in all six molecules (the asymmetric unit of Lig2Zr(O-tert-Bu)2 contains two molecules) may signify a similar available space for polymeryl growth and monomer coordination. A comparison of bond lengths and angles reveals several small but consistent differences that may shed light on the reactivity and stereoregulating ability of these systems. In all molecules the Zr-O(dihalo-phenolate) bond is longer than the Zr-O(dialkylphenolate) bond probably because of weaker donation to the zirconium by the electron-poor phenolate oxygen. More surprisingly, a similar trend is found for the Zr-N bonds: in each molecule the longer of the two is the one bound (via a methylene bridge) to the more electron-poor phenolate. In most molecules the slightly shorter of the two Zr-O(tert-Bu) bonds is trans to


Organometallics, Vol. 28, No. 5, 2009 1395

Scheme 3. Representative Synthetic Procedure of Nonsymmetric Salan Ligand Precursors

Table 1. Selected Bond Lengths (Å) and Angles (deg) for Lig2Zr(O-t-Bu)2 and Lig7-10Zr(O-t-Bu)2 entry 1 2 3 4 5 6 7 8 9 f

length/angle a

O-Zr-O Zr-O(Ar)b Zr-O(Ar)c Zr-O-C(t-Bu)d Zr-O-C(t-Bu)e Zr-Nf Zr-Ng Zr-O(t-Bu)h Zr-O(t-Bu)i

Lig2Zr(O-t-Bu)2(1)

Lig2Zr(O-t-Bu)2(2)

Lig7Zr(O-t-Bu)2

Lig8Zr(O-t-Bu)2

Lig9Zr(O-t-Bu)2

Lig10Zr(O-t-Bu)2

107.8(1) 2.055(2) 2.019(2) 160.9(2) 176.2(3) 2.463(3) 2.491(3) 1.918(2) 1.940(2)

108.0(1) 2.086(2) 2.044(2) 163.6(2) 166.7(2) 2.457(3) 2.491(3) 1.909(2) 1.929(3)

107.8(1) 2.086(3) 2.035(2) 168.7(2) 164.4(3) 2.462(3) 2.490(3) 1.928(2) 1.931(3)

107.4(1) 2.081(3) 2.027(3) 166.5(3) 166.3(3) 2.455(4) 2.493(4) 1.924(3) 1.931(3)

107.3(2) 2.076(4) 2.035(3) 166.3(4) 167.2(4) 2.447(4) 2.492(4) 1.932(4) 1.928(3)

107.0(2) 2.079(4) 2.017(4) 148.4(4) 169.0(4) 2.442(5) 2.489(5) 1.928(4) 1.946(4)

a Angle between labile ligands. b Halo-substituted phenol. c Alkyl-substituted phenol. d Proximal to hindered site. e Proximal to unhindered site. N-CH2 bound to alkyl-substituted phenol. g N-CH2 bound to halo-substituted phenol. h trans to longer Zr-N bond. i trans to shorter Zr-N bond.

the longer Zr-N bond, but this may be too small to be significant. Another notable structural feature is that all Zr-O-CMe3 angles except for one are higher than 160°, consistent with strong π-donation from the oxygen to the zirconium. An exceptional angle (148.4°) is found in Lig10Zr(Otert-Bu)2 for the O-tert-Bu unit proximal to the adamantyl group, from which it is bending away. This may be related to the strong directing ability of the adamantyl group (Vide infra). The {[ONNO′]-ZrBn2}-type complexessthe precatalysts in R-olefin polymerizationswere all obtained as yellow solids in high yields. Their 1H NMR spectra support the formation of single isomers of C1-symmetry. Single crystals of Lig2ZrBn2 and Lig6ZrBn2 suitable for X-ray analysis were grown from suitable solvents, and their structures were solved, revealing the typical fac-fac Salan wrapping (Figure 5, Table 2). In both structures, one of the benzyl groups binds in a “classical” η1mode with a Zr-C-C angle of ca. 125.3°, while the other

benzyl group is severely bent, binding in a η2-mode via the ipso carbon. The bending is more acute in Lig2ZrBn2 (89.2°) than in Lig6ZrBn2 (92.2°). The zirconacyclopropane ring and the methylene carbon of the other benzyl group are coplanar, yielding an essentially heptacoordinate zirconium center of pentagonal bipyramidal geometry. We attribute the high coordination number of these seemingly crowded molecules to their electron deficiency. Notably, the η2-binding benzyl group in Lig2ZrBn2 is located proximal to the less sterically demanding (chloro-substituted) phenolate, whereas the η2-binding benzyl group in Lig6ZrBn2 is located proximal to the more sterically demanding (trityl-substituted) phenolate. The significance of this difference in location and its possible relationship to stereoregulation is currently under investigation. 1-Hexene Polymerization Studies. The activity and stereoregulating properties in 1-hexene polymerization of the zirconium complexes of the nonsymmetric Salans were studied by

Figure 4. Stick representations of the X-ray structures of (from left) Lig2Zr(O-tert-Bu)2, Lig7Zr(O-tert-Bu)2, Lig8Zr(O-tert-Bu)2, Lig9Zr(O-tert-Bu)2, and Lig10Zr(O-tert-Bu)2.


Cohen et al.

Figure 5. Stick representations of the X-ray structures of Lig2ZrBn2 (left) and Lig6ZrBn2. Table 2. Selected Distances (Å) and Angles (deg) for Lig2ZrBn2 and Lig6ZrBn2 entry 1 2 3 4 5 6 7

length/angle a

Zr-O Zr-Ob C-Zr-Cc Zr-C-Cd Zr-C-Ce Zr-Nf Zr-Ng

Lig2ZrBn2

Lig6ZrBn2

2.009(6) 1.993(6) 118.0(3) 89.3(5) 125.5(6) 2.480(7) 2.474(6)

2.014(2) 2.006(2) 114.5(1) 125.3(2) 92.2(2) 2.566(2) 2.410(2)

a Halo-substituted phenol. b Alkyl-substituted phenol. c Angle between labile ligands. d Proximal to unhindered site. e Proximal to hindered site. f N-CH2 bound to dichloro-substituted phenol. g N-CH2 bound to alkyl-substituted phenol.

activating the precatalysts Lig1-10ZrBn2 with the cocatalyst tris(pentafluorophenyl)borane in neat monomer at room temperature. All complexes were found to lead to active polymerization catalysts. The poly(1-hexene) samples obtained were analyzed by GPC for determination of molecular weights and molecular weight distributions. 13C NMR spectroscopy was employed for determination of the type of tacticity and its degree at the pentad level, relying on the known chemical shifts of C-3 of poly(1-hexene).34 These results are summarized in Table 3. Very clear trends that are outlined below are evident from this table. Activity. The series of the C1-symmetric catalysts based on the diaminoethane skeleton, i.e., Lig1-6ZrBn2, exhibited activities that were strongly dependent on the phenolate substituents on both rings. The highest activity of 1300 g mmol-1 h-1 was recorded for Lig2ZrBn2, featuring a dichloro-phenolate and a di-tert-Bu phenolate. This activity is an average between those of the two parent symmetric Salan zirconium catalysts: low activity of the complex featuring di-tert-Bu phenolates and high activity of the complex featuring dichloro phenolates. Changing the chloro substituents to bigger and less electron-withdrawing halo-groups, dibromo (Lig3ZrBn2) or diiodo (Lig4ZrBn2)s moving from left to right in Figure 3sresulted in decreased activity. Increasing the size of the substituents on the other phenolate ring to 1-adamantyl (Lig5ZrBn2) or trityl (Lig6ZrBn2)smoving down in Figure 3syields the same result. Lig1ZrBn2, containing para-Cl and ortho-H groups, shows a (34) Asakura, T.; Demura, M.; Nishiyama, Y. Macromolecules 1991, 24, 2334.

low activity despite its electron deficiency. The series of the C1-symmetric catalysts based on the diaminocyclohexane skeleton, i.e., Lig7-9ZrBn2, exhibited lower activities, consistent with the tendency of these more rigid systems for reduced activities. These activities were essentially insensitive to the nature of the halo substituents. Molecular Weight of the Polymers. The narrow molecular weight distributions of all polymer samples (PDI ) 1.4-2.0) signify homogeneous (“single-site”) catalysis. The molecular weights of all polymers obtained are significantly higher than those obtained from the symmetric halo-substituted Salan zirconium catalysts (that yielded oligomers). This may be attributed to the difficulty in adopting a conformation suitable for chain transfer via a β-hydrogen transfer due to increased crowding. Surprisingly, the molecular weights are also higher than those of the polymers obtained from the symmetric bulkyalkyl-substituted symmetric Salan zirconium catalysts. This may simply reflect a higher propagation to chain transfer ratio in these active catalysts. Increasing the steric bulk of the halocontaining phenolate ring in the diaminoethane-based Salan ligands (Lig1ZrBn2 to Lig4ZrBn2, going right in Figure 3) leads to a gradual increase of polymer molecular weight; a similar trend is observed for the other alkyl-containing phenolate ring (Lig2ZrBn2 to Lig5ZrBn2 to Lig6ZrBn2, going down in Figure 3). In contrast, the molecular weights of the polymers obtained from the diaminocyclohexane-based Salan complexes are all high.35 A similar behavior was previously observed for the symmetric Salan zirconium complexes and was attributed to the rigidity of the cyclohexane skeleton. Tacticity of the Polymers. Except for the polymer obtained from Lig6ZrBn2, all the polymers appear stereoregular. While the degree of stereoregularity varies, the dominance of the mmmm pentad in all the stereoregular samples implies that they are isotactic. No evidence for hemiisotacticity, which would be discernible by an rrrr pentad of the same magnitude as the mmmm pentad, was found. In fact, the rrrr pentad is hardly observable in the less stereoregular polymers and practically absent in the more stereoregular ones. This implies that the common mechanism in which consecutive migratory insertions occur in the two (differently directing) independent diaste(35) These molecular weights are higher than expected based on calculated catalyst activity and polymerization time and imply partial catalyst activation.



Table 3. Data for Polymerization of Neat 1-Hexene with Lig1-10ZrBn2/B(C6F5)3a entry

catalyst

tp (min)

yield (g)

[cat.] (µmol)

activityb

Mw

Mw/Mn

[mmmm]c

1 2 3 4 5 6 7 8 9 10

Lig1ZrBn2 Lig2ZrBn2 Lig3ZrBn2 Lig4ZrBn2 Lig5ZrBn2 Lig6ZrBn2 Lig7ZrBn2 Lig8ZrBn2 Lig9ZrBn2 Lig10ZrBn2

70 9 25 55 15 225 60 55 60 60

0.40 2.90 2.85 1.88 1.28 1.51 0.66 0.56 0.54 3.13

13.9 13.3 11.9 10.9 12.7 10.9 12.4 11.6 10.1 10.3

23 1300 580 190 360 37 53 55 54 300

23 500 50 000 63 000 83 000 73 000 112 000 241 000 325 000 285 000 155 000

1.9 1.8 1.7 1.7 1.9 1.4 1.9 1.7 2.0 1.9

33 54 55 76 82 17 49 60 75 95

a

Conditions: 5.0 mL (3.4 g) of neat 1-hexene, RT. b g mmol-1 h-1. c Determined by 13C NMR spectroscopy.

Figure 6. 13C NMR spectra of poly(1-hexene) obtained from Lig1ZrBn2 (bottom) to Lig4ZrBn2.

reotopic sites is probably not a viable one for these Salan complexes. Moreover, as the tacticity increases, the only pentad remaining distinctly observable is the mrrm pentad (with the overlapping mmmr and mmrr pentads appearing as a shoulder of the dominant mmmm pentad). This trend is typical of C2symmetric catalysts (having homotopic sites) that operate by the enantiomorphic site control mechanism. Namely, the stereodirecting character of these C1-symmetric catalysts is equivalent to C2-symmetric catalysts having intermediate-size phenolate substituents. It is notable that the increasing of the size of substituents on both rings increased the isotacticity of the polymers (Lig1ZrBn2 to Lig4ZrBn2, going right in Figure 3, and Lig2ZrBn2 to Lig5ZrBn2, going down in Figure 3). The 13C NMR spectra demonstrating these two gradual steric changes are shown in Figures 6 and 7, respectively. The stereoirregularity of the polymer obtained from Lig6ZrBn2 may result from the spreading out of the trityl groups beyond a single quadrant or site epimerization to the less stereodirecting site. It is also notable that very similar tacticities were obtained for diaminoethane- and diaminocyclohexane-based catalysts that feature the same phenolate rings, i.e., Lig2ZrBn2 and Lig7ZrBn2, Lig3ZrBn2 and Lig8ZrBn2, and Lig4ZrBn2 and Lig9ZrBn2. Namely, the difference between the diaminoethane and the diaminocyclo-

hexane skeletons that affected molecular weights and activities had no apparent effect on tacticity induction in these C1symmetric Salan complexes. To reveal whether the streoregularity was sensitive to polymerization conditions, various parameters were explored in the polymerization of 1-hexene employing Lig2ZrBn2. These included dilution of the polymerization mixture in inert solvent (n-heptane), the polymerization at lower temperatures, and the employment of an excess of B(C6F5)3 cocatalyst. If site epimerization is a viable process, then dilution of the monomer is expected to favor it relative to migratory insertion, while lowering the polymerization temperature is expected to work in the opposite direction. The excess of cocatalyst may play a role if coordination of the borane cocatalyst to the chloro group is in effect increasing its effective bulk. However, as evident from Table 4, the isotacticity remained essentially constant under all conditions.36 With iodo-phenolate substitution leading to the highest tacticity induction of all halo-phenolates, and 1-adamantylphenolate substitution leading to the highest tacticity induction of all alkyl-phenolates, it seemed plausible that combining these two in a single nonsymmetric Salan ligand may be advantageous in terms of catalyst activity, polymer molecular weight, and


Cohen et al.

Figure 7. 13C NMR spectra of poly(1-hexene) obtained with Lig2ZrBn2 (bottom), Lig5ZrBn2, and Lig6ZrBn2. Table 4. Polymerization Data of Poly(1-hexene) Obtained from Lig2Zr(Bn)2/B(C6F5)3 under Different Conditions entry

1-hexene (mL)

heptane (mL)

temp (°C)

catalyst (µmol)

cocatalyst (µmol)

tp (min)

Mw

Mw/Mn

[mmmm]a

1 2 3 4 6 7 9 10 11

5 5 5 5 5 5 5 5 5

0 15 25 50 0 0 0 0 0

25 25 25 25 0 -13 25 25 25

13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3

19.9 19.9 19.9 19.9 19.9 19.9 39.8 66.4 117.2

10 70 85 140 30 180 15 15 15

50 000 53 500 44 400 60 300 61 500 70 000 42 000 36 500 40 000

1.82 1.56 1.96 1.17 1.89 1.69 1.69 1.84 1.91

54 50 52 55 53 56 54 54 54

a

Determined by 13C NMR spectroscopy.

isotacticity. This proved to be the case. Upon activation, Lig10ZrBn2 afforded a highly active catalyst, yielding a high molecular weight polymer with almost perfect isotacticity of [mmmm] ) 95%, as may be appreciated from Table 2 and Figure 8.37 In comparison to the prototypical C2-symmetric Salan complex that featured tert-Bu phenolate groups,14 Lig10ZrBn2 is about 20 times more active and leads to a polymer of about 10 times higher molecular weight after the same period of time, while its isospecificity is almost as perfect.

Discussion The stepwise synthesis of the nonsymmetrically substituted Salan ligands and the generation of well-defined complexes (36) Preliminary experiments indicated that polymerization of 1-hexene by Lig2ZrBn2 activated with either [Ph3C][B(C6F5)4] or [PhNMe2H][B(C6F5)4] (1.5 equiv) yielded poly(1-hexene) of similar isotacticity and molecular weights as that obtained from Lig2ZrBn2/B(C6F5)3. Polymerization of 1-hexene by Lig2ZrBn2 activated with MAO (500 equiv) led to poly(1hexene) of slightly reduced isotacticity and considerably reduced molecular weight. (37) A dibenzylzirconium complex of a Salan ligand with the same phenolates and trans-1,2-diaminocyclohexane skeleton yielded poly(1hexene) having the same degree of isotacticity.

having two distinct sites demonstrate that tailor-made catalysts of this family can be realized. This applies to both diaminoethane-based Salans and the chiral trans-1,2-diaminocyclohexanebased Salans that led to predetermined single diastereoisomers. Such complexes may find use in asymmetric catalysis that employs chiral-at-metal complexes. While the overall structures of the di(O-tert-Bu) complexes revealed from crystallographic studies are almost superimposable, the slight observed differences in bond lengths and angles may be relevant to the properties of the corresponding catalysts. In particular, the slightly longer N-Zr dative bond of the arm leading to the electronwithdrawing phenolate indicates that a ligand trans to it may bind stronger (trans influence). In the active catalyst, a (freely site-epimerizing) polymeryl chain may prefer to occupy this position, which is the stereodirecting one due to its spatial proximity to the bulky phenolate. The severe bending of one of the benzyl groups in the two structures that contain a dichlorophenolate, Lig2ZrBn2 and Lig6ZrBn2, reflects their electron deficiency and implies a spacious equatorial plane. The most intriguing aspect of these catalysts’ activity is their isospecificity induction. The poly(R-olefin) chain has been compared to a recording tape that bears the signature of the



Figure 8. 13C NMR of poly(1-hexene) obtained from Lig10ZrBn2/B(C6F5)3.

catalyst from which it was produced.38 Poly(1-hexene) is not a very sensitive “recording tape” due to overlap of pentads, yet the apparent signature seems to be more in accord with C2symmetric catalysts than with C1-symmetric catalysts. Lig2ZrBn2 may be described as a hybrid of two symmetric complexes, one leading to aspecific polymerization (bearing dichlorophenolates) and the other leading to highly isospecific polymerization (bearing di-tert-Bu-phenolates). Independent stereodirecting character of the two sites combined with no site epimerization in Lig2ZrBn2 would have led to a hemiisotactic polymer. This is not observed. In C1-symmetric metallocenes, overcrowding of one site causes site epimerization to the less sterically congested site, which is face selective, leading to isospecific polymerization. However, for the Salan complexes described in the current work, the less sterically congested site is also the less directing site, thus an equivalent process should have yielded poorly tactic polymers.39 One may argue that due to the difference in trans influence, the chain back-skip would prefer the opposite direction, placing the polymeryl chain in the more crowded and face-selective site. However, on its own, such a process cannot explain the higher isospecificity induced by Lig4ZrBn2 relative to that induced by Lig2ZrBn2. All in all, an average steric effect of both sites seems to be in effect in every insertion step, leading to the apparent C2-symmetry character. The constant stereoregularity irrespective of polymerization conditions implies that the process responsible for the averaging of the two different phenolates (possibly via site epimerization) is very fast.40 (38) Busico, V.; Cipullo, R.; Monaco, G.; Vacatello, M.; Segre, A. L. Macromolecules 1997, 30, 6251. (39) Such a process may explain the poor tacticity of the polymer obtained from Lig6ZrBn2. (40) The “alternating” mechanism,10 invoking different stereoselective sites and no site epimerization could be in effect, with the assumption that the halo-substituted phenolates are weakly stereodirecting rather than nonstereodirecting, a phenomenon that would be hard to observe in the complexes of the symmetric Salan ligands but may become apparent with the nonsymmetric systems. This mechanism seems to be at odds with the considerably higher isospecificity induced by Lig5ZrBn2 relative to Lig2ZrBn2.

Conclusions The metallocene catalysts, and in particular the ansametallocenes, have been the center of interest of polymerization catalyst development, because the rigid wrapping of the ligand and the well-defined symmetry enabled a logical structure-activity study by introduction of well-designed substitution pattern. The current study demonstrates that the group 4 Salan complexes constitute a close match to the metallocenes in terms of finetuning ability of the active site by stepwise substitutions. Such fine-tuning enabled the development of catalysts of relatively high activities, yielding high molecular weight polymers of high tacticities. Yet, the mode of stereoregulation of this class of nonmetallocene catalysts seems to divert from that of the metallocenes, as the two sites seem to work in concert, yielding polymers that bear the signature of C2-catalysts rather than C1catalysts. We are currently studying the polymerization of other monomers with these catalysts, trying to gain mechanistic insight and develop new modes of activity.

Experimental Section General Comments. All experiments employing metal complexes were performed under an atmosphere of dry nitrogen in a nitrogen-filled glovebox. Ether was purified by distillation under dry argon atmosphere from purple Na/benzophenone solution. Pentane was washed with HNO3/H2SO4 prior to distillation from Na/benzophenone/tetraglyme. Toluene was refluxed over Na and distilled. 2,4-Di-tert-butylphenol, 4-methylphenol, 5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde, 3,5-dibromosalicylaldehyde, 3,5-diiodosalicylaldehyde, paraformaldehyde, N,N′-dimethylethylenediamine, rac-N,N′-dimethyl-1,2-trans-diaminocyclohexane, triethylamine, 1-chloroadamantane, trityl chloride, p-cresol, and Zr(IV) tert-butoxide were purchased from Aldrich and used as received. 1-Hexene (98%, ABCR) was dried by neutral alumina immediately prior to use. Tris(pentafluorophenyl)borane (97%) was purchased from Strem and used as received. 2-(Bromomethyl)-4,6-bis(tertbutyl)phenol,41 2-adamantyl-4-methylphenol,42 and tetrabenzylzirconium43 were synthesized according to published procedures. All NMR data were recorded on a Bruker Avance-400 spectrometer. CDCl3 was used as solvent for the intermediate organic compounds and for the poly(1-hexene) samples (chemical shift of TMS at δ

1400 Organometallics, Vol. 28, No. 5, 2009 0.00 and 13C chemical shift of the solvent at δ 77.16 were used as reference). C6D6 was used as solvent for the ligand precursors and for the metal complexes (protio impurities in benzene-d6 at δ 7.15 and 13C chemical shift of benzene at δ 128.70 were used as reference). Poly(1-hexene) molecular weights were determined by gel permeation chromatography (GPC) using a TSKgel GMHHR-M column on a Jasco instrument equipped with a refractive index detector. Molecular weight determination was carried out relative to polystyrene standards using tetrahydrofuran (HPLC grade, distilled and filtered under vacuum prior to use) as the eluting solvent. Elemental analyses were performed in the microanalytical laboratory in the Hebrew University of Jerusalem. X-ray diffraction measurements were performed on a Nonius Kappa CCD diffractometer system, using Mo KR (λ ) 0.7107 Å) radiation. The analyzed crystals were embedded within a drop of viscous oil and freeze-cooled to ca. 110 K. The structures were solved by a combination of direct methods and Fourier techniques using SIR97 software44 and were refined by full-matrix least-squares with SHELXL-97.45 Synthesis of Diaminoethane-monophenolateH,Cl. To a stirred solution of 5-chlorosalicylaldehyde (1.20 g, 7.7 mmol) in methanol (40 mL) was added dropwise a solution of N,N′-dimethylethylendiamine (0.85 g, 9.6 mmol) in methanol (10 mL). The solution was stirred for 2 h, and NaBH4 (0.6 g, 15.9 mmol) was added in small portions. The solution was stirred for another hour, and another portion of NaBH4 (0.6 g, 15.9 mmol) and some ice were added, leading to precipitation of a white solid. The reaction mixture was stirred for an additional 2 h. The white solid was collected by vacuum filtration (1.44 g, 82% yield): mp 66 °C; 1H NMR δ 7.10 (dd, J ) 2.6 Hz, J ) 8.6 Hz, 1H), 6.95 (d, J ) 2.6 Hz, 1H), 6.74 (d, J ) 8.6 Hz, 1H), 3.62 (s, 2H), 2.78 (t, J ) 6.5 Hz, 2H), 2.61 (t, J ) 6.2 Hz, 2H), 2.44 (s, 3H), 2.29 (s, 3H); 13C NMR δ 156.7 (C), 128.8 (CH), 128.7 (CH), 124.1 (C), 123.7 (C), 117.9 (C), 60.4 (CH2), 56.5 (CH2), 49.1 (CH2), 42.1 (CH3), 36.5 (CH3). Diaminoethane-monophenolateCl,Cl was synthesized according to the above procedure from 3,5-dichlorosalicylaldehyde and N,N′dimethylethylendiamine (3.5 g, 51% yield): mp 163 °C; 1H NMR δ 7.22 (d, J ) 2.6 Hz, 1H), 6.86 (d, J ) 2.6 Hz, 1H), 3.45 (s, 2H), 2.94 (t, J ) 6.3 Hz, 2H), 2.65 (t, J ) 6.3 Hz, 2H), 2.49 (s, 3H), 2.25 (s, 3H); 13C NMR δ 155.9 (C), 128.5 (CH), 127.9 (CH), 126.2 (C), 122.0 (C), 120.0 (C), 57.7 (CH2), 53.8 (CH2), 47.1 (CH2), 42.4 (CH3), 34.3 (CH3). Diaminoethane-monophenolateBr,Br was synthesized according to the above procedure from 3,5-dibromosalicylaldehyde and N,N′dimethylethylendiamine (2.5 g, 86% yield): mp 160 °C; 1H NMR δ 7.52 (d, J ) 2.4 Hz, 1H), 7.03 (d, J ) 2.4 Hz, 1H), 3.51 (s, 2H), 2.89 (t, J ) 6.4 Hz, 2H), 2.64 (t, J ) 6.3 Hz, 2H), 2.48 (s, 3H), 2.26 (s, 3H); 13C NMR δ 156.3 (C), 134.0 (CH), 131.1 (CH), 126.1 (C), 112.1 (C), 108.1 (C), 58.5 (CH2), 54.6 (CH2), 47.7 (CH2), 42.1 (CH3), 35.0 (CH3). Diaminoethane-monophenolateI,I was synthesized according to the above procedure from 3,5-diiodosalicylaldehyde and N,N′dimethylethylendiamine (4.23 g, 100% yield): mp 162 °C; 1H NMR δ 7.89 (d, J ) 2.1 Hz, 1H), 7.21 (d, J ) 2.1 Hz, 1H), 3.52 (s, 2H), 2.84 (t, J ) 6.5 Hz, 2H), 2.62 (t, J ) 6.3 Hz, 2H), 2.47 (s, 3H), 2.26 (s, 3H); 13C NMR δ 158.2 (C), 145.5 (C), 145.2 (CH), 137.5 (CH), 137.0 (C), 125.1 (C), 59.3 (CH2), 55.4 (CH2), 48.3 (CH2), 41.8 (CH3), 35.7 (CH3). (41) Appiah, W. O.; DeGreef, A. D.; Razidlo, G. L.; Spessard, S. J.; Pink, M., Jr.; Hofmeister, G. E. Inorg. Chem. 2002, 41, 3656. (42) Arredondo, Y.; Moreno-Ma, M.; Pleixats, R. Synth. Commun. 1996, 26, 3885. (43) Zucchini, U.; Alizzati, E.; Giannini, U. J. J. Organomet. Chem. 1971, 26, 357. (44) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.; Burla, M. C.; Polidori, G.; Camali, M. J. Appl. Crystallogr. 1994, 27, 435. (45) Sheldrick, G. M. SHELXL-97 Program; University of Go¨ttingen: Germany, 1996.

Cohen et al. Diaminocyclohexane-monophenolateCl,Cl was synthesized according to the above procedure from 3,5-dichlorosalicylaldehyde and rac-N,N′-dimethyl-1,2-trans-diaminocyclohexane (2.0 g, 99%): mp 187 °C; 1H NMR δ 7.18 (d, J ) 2.7 Hz, 1H), 6.80 (d, J ) 2.7 Hz, 1H), 3.93 (d, J ) 12.0 Hz, 1H, AB system), 3.11 (m, 1H), 2.71 (d, J ) 12.0 Hz, 1H, AB system), 2.45 (s, 3H), 2.22 (s, 3H), 2.05 (m, 1H), 1.71 (m, 4H), 1.22 (m, 4H); 13C NMR δ 159.0 (C), 128.9 (CH), 128.6 (C), 128.3 (CH), 122.6 (C), 116.4 (C), 63.5 (CH), 56.9 (CH), 51.5 (CH2), 39.4 (CH3), 28.0 (CH2), 26.7 (CH3), 25.3 (CH2), 22.6 (CH2). Diaminocyclohexane-monophenolateBr,Br was synthesized according to the above procedure from dibromosalicylaldehyde and rac-N,N′-dimethyl-1,2-trans-diaminocyclohexane (2.0 g, 88%): mp 193 °C; 1H NMR δ 7.48 (d, J ) 2.5 Hz, 1H), 6.98 (d, J ) 2.5 Hz, 1H), 3.88 (d, J ) 12.4 Hz, 1H, AB system), 2.90 (m, 1H), 2.88 (d, J ) 12.3 Hz, 1H, AB system), 2.48 (s, 3H), 2.43 (td, J ) 3.24, J ) 10.8, 1H), 2.20 (s, 3H), 2.01 (d, J ) 7.9, 1H), 1.81 (d, J ) 6.2, 2H), 1.72 (d, J ) 3.6, 1H), 1.17 (m, 4H); 13C NMR δ 158.5 (C), 133.8 (CH), 131.9 (CH), 128.3 (C), 113.5 (C), 105.1 (C), 65.0 (CH), 57.8 (CH), 52.4 (CH2), 38.7 (CH3), 29.0 (CH2), 28.5 (CH2), 25.2 (CH2), 25.2 (CH2), 22.8 (CH2). Diaminocyclohexane-monophenolateI,I was synthesized according to the above procedure from 3,5-diiodosalicylaldehyde and rac-N,N′-dimethyl-1,2-trans-diaminocyclohexane (0.36 g, 2.5 mmol) (1.3 g, 99%): mp 193 °C; 1H NMR δ 7.88 (d, J ) 2.1 Hz, 1H), 7.20 (d, J ) 2.0 Hz, 1H), 3.84 (d, J ) 12.8 Hz, 1H, AB system), 3.07 (d, J ) 12.8 Hz, 1H, AB system), 2.73 (td, J ) 3.0, J ) 10.1, 1H), 2.48 (s, 3H), 2.44 (td, J ) 3.1, J ) 10.3, 1H), 2.20 (s, 3H), 1.99 (m, 2H), 1.80 (m, 2H), 1.16 (m, 4H); 13C NMR (100.67 MHz, C6D6), δ 198.6 (C), 160.4 (C), 160.2 (C), 145.8 (CH), 138.9 (CH), 127.8 (C), 67.4 (CH), 59.3 (CH2), 54.3 (CH), 51.5 (CH3), 38.6 (CH3), 31.1 (CH2), 31.1 (CH2), 26.0 (CH2), 23.9 (CH2). Synthesis of 6-(1-Adamantyl)-2-(bromomethyl)-4-methylphenol. To 25 mL of glacial acetic acid were added 2-(1-adamantyl)4-methylphenol (9.2 g, 38.1 mmol) and parafomaldehyde (1.3 g, 42.0 mmol). The flask was warmed to 40 °C until the reactants had fully dissolved. Anhydrous hydrogen bromide gas was passed into the reaction mixture. Heat evolved and the temperature of the mixture was kept below 75 °C. After 30 min a white precipitate had formed and the HBr addition was stopped. The solid product was filtered off, washed three times with cold petroleum ether, and left to dry in air (10.7 g, 84%): mp 149 °C; 1H NMR δ 7.07 (d, J ) 1.9 Hz, 1H), 6.94 (d, J ) 1.7 Hz, 1H), 5.26 (s, 1H), 4.6 (s, 2H), 2.28 (s, 3H), 2.16 (s, 1H), 2.15 (s, 6H), 2.12 (m, 3H), 1.81 (m, 6H); 13C NMR δ 152.4 (C), 138.4 (C), 130.2 (C), 129.9 (CH), 128.4 (CH), 124.5 (C), 41.2 (CH2), 37.5 (CH2), 37.3 (CH), 32.7 (C), 29.5 (CH2). Synthesis of 2-(Bromomethyl)-4-methyl-6-tritylphenol. To 20 mL of glacial acetic acid were added 4-methyl-2-tritylphenol (6.3 g, 17.9 mmol) and parafomaldehyde (0.6 g, 19.7 mmol). The flask was warmed to 65 °C, but the reactants did not dissolve. Anhydrous hydrogen bromide gas was passed into the reaction mixture. Heat had evolved and the temperature of the mixture was kept below 75 °C. The HBr addition was stopped after 30 min when the solution was completely saturated and a white precipitate had formed. The solid product was filtered off, washed three times with cold petroleum ether, and left to dry in air (5.80 g, 78%): mp 130 °C; 1 H NMR δ 7.23-7.30 (m, 10H), 7.17 (m, 3H), 7.16 (m, 2H), 7.11 (d, J ) 1.7 Hz, 1H), 6.84 (d, J ) 1.7 Hz, 1H), 4.66 (s, 1H), 4.44 (s, 2H), 2.16 (s, 3H); 13C NMR δ 151.0 (C), 144.4 (C), 134.0 (C), 132.4 (CH), 131.4 (CH), 131.1 (CH), 129.7 (C), 128.5 (CH), 127.4 (CH), 63.2 (CH2), 30.8 (CH3). Synthesis of Lig1H2. To a stirred solution of 2-(bromomethyl)4,6-bis(tert-Bu)phenol (0.91 g, 3.0 mmol) was added diaminoethane-monophenolateH,Cl (0.78 g, 3.0 mmol) in dry THF (100 mL). After complete dissolution, triethylamine (0.46 mL, 3.3 mmol) was added dropwise. A white solid formed immediately and the reaction

C1-Symmetric Zirconium Salan Polymerization Catalysts flask had warmed. The reaction mixture was stirred for 2 h, and the white solid was removed by filtration. The volatiles were removed under vacuum, yielding a yellow solid. The solid was dissolved in 50 mL of dichloromethane, the solution was washed three times with water (60 mL), the organic layer was dried over sodium sulfate, and the solvent was removed to yield an orange solid, which was precipitated from methanol as a white solid and collected by vacuum filtration (0.88 g, 58% yield): mp 112 °C; 1H NMR δ 7.52 (d, J ) 2.4 Hz, 1H), 7.02 (d, J ) 2.6 Hz, J ) 8.6 Hz, 1H), 6.89 (d, J ) 2.3 Hz, 1H), 6.81 (d, J ) 8.6 Hz, 1H), 6.78 (d, J ) 2.5 Hz, 1H), 3.23 (s, 2H), 2.93 (s, 2H), 2.03 (t, J ) 5.5 Hz, 1H), 1.96 (t, J ) 6.3 Hz, 1H), 1.75 (s, 3H), 1.70 (s, 9H), 1.63 (s, 3H), 1.37 (s, 9H); 13C NMR δ 157.3 (C), 154.7 (C), 140.7 (CH), 136.0 (C), 128.9 (CH), 128.3 (CH), 123.6 (C), 123.4 (CH), 123.2 (CH), 121.4 (C), 117.8 (CH), 62.5 (CH2), 60.1 (CH2), 53.6 (CH2), 53.1 (CH2), 40.9 (CH3), 35.1 (C), 31.8 (CH3), 29.8 (CH3). Anal. Calcd for C26H39ClN2O2: C, 69.85; H, 8.79; N, 6.27. Found: C, 69.82; H, 8.79; N, 5.98. Lig2H2 was synthesized according to the procedure employed for Lig1H2 from 2-(bromomethyl)-4,6-bis(tert-butyl)phenol and diaminoethane-monophenolateCl,Cl and was purified by flash vacuum chromatography over silica gel 60H, eluted with an increasing concentration of dichloromethane in petroleum ether. Lig2H2 was recrystallized from pentane as a white solid (2.07 g, 43% yield): mp 86 °C; 1H NMR δ 7.51 (d, J ) 2.1 Hz, 1H), 7.25 (d, J ) 2.1 Hz, 1H), 6.90 (d, J ) 2.0 Hz, 1H), 6.54 (d, J ) 2.1 Hz, 1H), 3.23 (s, 2H), 2.82 (s, 2H), 2.01 (t, J ) 6.5 Hz, 2H), 1.92 (t, J ) 6.7 Hz, 2H), 1.75 (s, 3H), 1.69 (s, 9H), 1.54 (s, 3H), 1.37 (s, 9H); 13C NMR δ 154.7 (C), 153.4 (C), 140.8 (C), 136.1 (C), 129.0 (CH), 128.0 (C), 126.6 (CH) 124.0 (C), 123.4 (CH), 123.2 (CH), 122.1 (CH), 121.3 (CH), 62.5 (CH2), 60.5 (CH2), 53.6 (CH2), 52.9 (CH2), 40.9 (CH3), 40.7 (CH3), 35.1 (C), 34.2 (C), 31.8 (CH3), 29.8 (CH3). Anal. Calcd for C26H38Cl2N2O2: C, 64.86; H, 7.95; N, 5.92. Found: C, 65.15; H, 8.05; N, 5.86. Lig3H2 was synthesized and purified according to the procedure employed for Lig2H2 from 2-(bromomethyl)-4,6-bis(tert-butyl)phenol and diaminoethane-monophenolateBr,Br (1.90 g, 47% yield): mp 103 °C; 1H NMR δ 7.58 (d, J ) 2.3 Hz, 1H), 7.51 (d, J ) 2.4 Hz, 1H), 6.89 (d, J ) 2.4 Hz, 1H), 6.71 (d, J ) 2.3 Hz, 1H), 3.22 (s, 2H), 2.78 (s, 2H), 2.01 (t, J ) 6.7 Hz, 1H), 1.89 (t, J ) 6.7 Hz, 1H), 1.74 (s, 3H), 1.69 (s, 9H), 1.51 (s, 3H), 1.36 (s, 9H); 13C NMR δ 154.8 (C), 154.7 (C), 140.8 (C), 136.1 (C), 134.5 (CH), 130.1 (CH), 124.4 (C), 123.4 (CH), 123.2 (CH), 121.3 (C), 111.6 (CH), 110.5 (CH), 62.5 (CH2), 60.4 (CH2), 53.6 (CH2), 52.9 (CH2), 40.9 (CH3), 40.6 (CH3), 35.1 (C), 34.2 (C), 31.8 (CH3), 29.8 (CH3). Anal. Calcd for C26H38Br2O2N2: C, 54.75; H, 6.71; N, 4.91. Found: C, 55.02; H, 6.87; N, 4.82. Lig4H2 was synthesized according to the procedure employed for Lig1H2 from 2-(bromomethyl)-4,6-bis(tert-butyl)phenol and diaminoethane-monophenolateI,I (0.8 g, 69% yield): mp 94 °C; 1H NMR δ 8.00 (d, J ) 1.8 Hz, 1H), 7.51 (d, J ) 2.2 Hz, 1H), 6.91 (d, J ) 1.2 Hz, 1H), 6.89 (d, J ) 2.1 Hz, 1H), 3.21 (s, 2H), 2.71 (s, 2H), 1.98 (t, J ) 5.6 Hz, 1H), 1.86 (t, J ) 6.7 Hz, 1H), 1.72 (s, 3H), 1.69 (s, 9H), 1.48 (s, 3H), 1.37 (s, 9H); 13C NMR δ 157.9 (C), 154.7 (C), 145.5 (CH), 140.8 (C), 136.9 (CH), 136.1 (C), 124.1 (C), 123.4 (CH), 123.2 (CH), 121.3 (C), 86.7 (CH), 80.6 (CH), 62.5 (CH2), 60.3 (CH2), 53.5 (CH2), 52.9 (CH2), 40.9 (CH3), 40.5 (CH3), 35.1 (C), 34.2 (C), 31.8 (CH3), 29.8 (CH3). Anal. Calcd. for C26H38I2O2N2: C, 47.00; H, 5.76; N, 4.22. Found: C, 46.72; H, 5.52; N, 3.95. Lig5H2 was synthesized and purified according to the procedure employed for Lig2H2 from 6-adamantyl-2-(bromomethyl)-4-methylphenol and diaminoethane-monophenolateCl,Cl (1.77 g, 76% yield): mp 127 °C; 1H NMR δ 7.26 (d, J ) 2.5 Hz, 1H), 7.11 (d, J ) 1.8 Hz, 1H), 6.57 (d, J ) 1.8 Hz, 1H), 6.54 (d, J ) 2.5 Hz, 1H), 3.18 (s, 2H), 2.84 (s, 2H), 2.44 (m, 6H), 2.29 (s, 3H), 2.14 (m, 3H), 1.99 (t, J ) 5.6 Hz, 1H), 1.80-1.92 (m, 6H), 1.75 (s, 3H), 1.55 (s,

Organometallics, Vol. 28, No. 5, 2009 1401 9H); 13C NMR δ 155.0 (C), 153.6 (C), 137.2 (C), 129.2 (CH), 128.7 (C), 127.6 (C), 127.4 (CH), 126.8(CH), 124.2 (CH), 123.5 (C), 122.4 (C), 122.1 (C), 62.4 (CH2), 60.3 (CH2), 53.9 (CH2), 52.9 (CH2), 41.1 (CH3), 40.9 (CH2), 37.6 (CH2), 37.2 (CH3), 29.7 (CH), 21.1 (C). Anal. Calcd for C29H38Cl2O2N2: C, 67.30; H, 7.40; N, 5.41. Found: C, 67.15; H, 7.54; N, 5.22. Lig6H2 was synthesized and purified according to the procedure employed for Lig2H2 from 2-(bromomethyl)-4-methyl-6-tritylphenol and diaminoethane-monophenolateCl,Cl (0.62 g, 41% yield): mp 106 °C; 1H NMR δ 7.53 (d, J ) 7.5 Hz, 6H), 7.35 (d, J ) 1.5 Hz, 1H), 7.24 (d, J ) 2.4 Hz, 1H), 7.11 (d, J ) 7.9 Hz, 1H), 7.01 (d, J ) 7.3 Hz, 1H), 6.61 (d, J ) 1.5 Hz, 1H), 6.53 (d, J ) 2.3 Hz, 1H), 3.10 (s, 2H), 2.80 (s, 2H), 2.11 (s, 3H), 1.85 (m, 1H), 1.68 (m, 1H), 1.54 (s, 3H), 1.41 (s, 3H); 13C NMR δ 154.4 (C), 153.3 (C), 146.5 (CH), 134.5 (C), 131.5 (CH), 131.1 (CH), 129.0 (CH), 128.5 (CH), 127.2 (CH), 127.0 (C), 126.6 (CH), 125.3 (CH), 123.9 (C), 123.3 (C), 122.1 (C), 122.0 (C), 63.7 (C), 61.5 (CH2), 60.3 (CH2), 53.6 (CH2), 53.1 (CH2), 40.8 (CH2), 40.7 (CH2), 20.8 (CH3). Anal. Calcd for C38H38Cl2O2N2 · 0.5H2O: C, 71.92; H, 6.04; N, 4.41. Found: C, 71.86; H, 6.00; N, 4.23. Lig7H2 was synthesized according to the procedure employed for Lig1H2 from 2-(bromomethyl)-4,6-bis(tert-butyl)phenol and diaminocyclohexane-monophenolateCl,Cl (0.7 g, 60% yield): mp 88 °C; 1H NMR δ 7.51 (d, J ) 2.4 Hz, 1H), 7.27 (d, J ) 2.5 Hz, 1H), 6.95 (d, J ) 2.4 Hz, 1H), 6.66 (d, J ) 2.5 Hz, 1H), 3.52 (d, J ) 13.1 Hz, 1H, AB system), 3.35 (d, J ) 13.0 Hz, 1H, AB system), 3.15 (d, J ) 13.7 Hz, 1H, AB system), 2.94 (d, J ) 13.3 Hz, 1H, AB system), 2.30 (td, J ) 10.8 Hz, J ) 3.0 Hz, 1H), 2.10 (td, J ) 10.8 Hz, J ) 3.0 Hz, 1H), 1.91 (s, 3H), 1.79 (s, 3H), 1.64 (s, 9H), 1.37 (s, 9H), 0.62 (m, 8H); 13C NMR δ 154.6 (C), 153.7 (C), 140.8 (C), 136.5 (C), 129.1 (CH), 126.9 (CH), 124.7 (C), 124.0 (CH), 123.4 (CH), 122.9 (C), 122.4 (C), 121.9 (C), 62.8 (CH), 60.8 (CH), 58.2 (CH2), 56.6 (CH2), 35.1 (CH3), 34.9 (C), 34.5 (CH3), 34.1 (C), 31.8 (CH2), 29.9 (CH3), 25.1 (CH2), 24.9 (CH2), 22.2 (CH2), 21.6 (CH2). Anal. Calcd for C30H44Cl2N2O2: C, 67.28; H, 8.26; N, 5.23. Found: C, 67.54; H, 8.57; N, 4.95. Lig8H2 was synthesized according to the procedure employed for Lig1H2 from 2-(bromomethyl)-4,6-bis(tert-butyl)phenol and diaminocyclohexane-monophenolateBr,Br (0.9 g, 62% yield): mp 164 °C; 1H NMR δ 7.61 (d, J ) 2.4 Hz, 1H), 7.52 (d, J ) 2.4 Hz, 1H), 6.96 (d, J ) 2.3 Hz, 1H), 6.84 (d, J ) 2.3 Hz, 1H), 3.52 (d, J ) 13.1 Hz, 1H, AB system), 3.36 (d, J ) 13.1 Hz, 1H, AB system), 3.13 (d, J ) 13.8 Hz, 1H, AB system), 2.92 (d, J ) 13.6 Hz, 1H, AB system), 2.29 (td, J ) 10.9 Hz, J ) 3.1 Hz, 1H), 2.08 (td, J ) 11.1 Hz, J ) 3.1 Hz, 1H), 1.90 (s, 3H), 1.77 (s, 3H), 1.66 (s, 9H), 1.38 (s, 9H), 1.32 (m, 3H), 0.67 (m, 5H); 13C NMR δ 155.2 (C), 154.7 (C), 140.7 (C), 136.4 (C), 134.5 (CH), 130.4 (CH), 125.1 (C), 124.0 (CH), 123.4 (CH), 123.0 (C), 111.8 (C), 110.2 (C), 62.6 (CH), 60.7 (CH), 58.3 (CH2), 55.7 (CH2), 35.2 (CH3), 34.9 (C), 34.5 (C), 34.2 (CH3), 31.8 (CH3), 29.9 (CH3), 25.1 (CH2), 24.9 (CH2), 22.2 (CH2), 21.6 (CH2). Anal. Calcd for C30H44Br2N2O2: C, 57.70; H, 7.10; N, 4.49. Found: C, 57.67; H, 7.06; N, 4.32. Lig9H2 was synthesized according to the procedure employed for Lig1H2 from 2-(bromomethyl)-4,6-bis(tert-butyl)phenol and diaminocyclohexane-monophenolateI,I (0.95 g, 70% yield): mp 118 °C; 1H NMR δ 8.04 (d, J ) 2.1 Hz, 1H), 7.53 (d, J ) 2.4 Hz, 1H), 7.04 (d, J ) 2.0 Hz, 1H), 6.96 (d, J ) 2.4 Hz, 1H), 3.52 (d, J ) 13.2 Hz, 1H, AB system), 3.36 (d, J ) 13.2 Hz, 1H, AB system), 3.07 (d, J ) 13.8 Hz, 1H, AB system), 2.88 (d, J ) 13.8 Hz, 1H, AB system), 2.27 (td, J ) 10.7 Hz, J ) 2.9 Hz, 1H), 2.06 (td, J ) 11.2 Hz, J ) 3.2 Hz, 1H), 1.89 (s, 3H), 1.74 (s, 3H), 1.67 (s, 9H), 1.54 (d, J ) 8, 1H), 1.38 (s, 9H), 1.27 (m, 2H), 0.64 (m, 4H); 13C NMR δ 158.3 (C), 154.7 (C), 145.6 (CH), 140.7 (C), 137.1 (CH), 136.4 (C), 124.7 (C), 123.9 (CH), 123.4 (CH), 121.8 (C), 86.9 (C), 80.3 (C), 62.3 (CH), 60.7 (CH), 58.4 (CH2), 55.5 (CH2), 35.2 (CH3), 34.9 (C), 34.6 (C), 34.2 (CH3), 31.8 (CH3), 30.0 (CH3), 25.0 (CH2),

1402 Organometallics, Vol. 28, No. 5, 2009 24.9 (CH2), 22.3 (CH2), 21.6 (CH2). Anal. Calcd for C30H44I2N2O2: C, 50.15; H, 6.17; N, 3.90. Found: C, 49.92; H, 6.31; N, 3.75. Lig10H2 was synthesized and purified according to the procedure employed for Lig1H2 from 6-adamantyl-2-(bromomethyl)-4-methylphenol and diaminoethane-monophenolateI,I (1.05 g, 89% yield): mp 148 °C; 1H NMR δ 8.01 (d, J ) 2.1 Hz, 1H), 7.11 (d, J ) 1.7 Hz, 1H), 6.90 (d, J ) 2.0 Hz, 1H), 6.56 (d, J ) 1.7 Hz, 1H), 3.16 (s, 2H), 2.74 (s, 2H), 2.44 (m, 6H), 2.28 (s, 3H), 2.14 (m, 3H), 1.96 (t, J ) 6.1 Hz, 1H), 1.80-1.92 (m, 6H), 1.73 (s, 3H), 1.50 (s, 3H); 13C NMR δ 158.1 (C), 155.1 (C), 145.7 (C), 137.1 (CH), 137.1 (CH), 127.5 (CH), 127.4 (CH), 124.3(C), 122.1 (C), 86.9 (C), 80.8 (C), 62.4 (CH2), 60.1 (CH2), 53.8 (CH2), 52.9 (CH2), 41.2 (CH3), 40.9 (CH2), 37.7 (CH2), 37.2 (CH3), 29.7 (CH), 21.1 (C). Anal. Calcd for C29H38I2N2O2: C, 49.73; H, 5.47; N, 4.00. Found: C, 50.00; H, 5.55; N, 3.84. Synthesis of Lig1Zr(O-tert-Bu)2. Lig1H2 (52.9 mg, 0.12 mmol) was dissolved in ca. 2 mL of ether and added dropwise to a solution of Zr(O-tert-Bu)4 (45.3 mg, 0.12 mmol) in ether. The solution was stirred at room temperature for 2 h. The solvent was removed under vacuum, and the resulting colorless oil was washed with pentane (2 mL). The solvent was removed under vacuum to yield a white solid (80.1 mg, 100%). 1H NMR δ 7.58 (d, J ) 2.5 Hz, 1H), 7.15 (dd, J ) 2.8 Hz, 1H), 6.93 (d, J ) 2.4 Hz, 1H), 6.80 (d, J ) 2.7 Hz, 1H), 6.65 (d, J ) 8.6 Hz, 1H), 4.59 (d, J ) 13.2 Hz, 1H, AB system), 4.42 (d, J ) 13.4 Hz, 1H, AB system), 2.77 (d, J ) 13.3 Hz, 1H, AB system), 2.76 (dt, J ) 3.2 Hz, J ) 13.6, 1H, AB system), 2.43 (dt, J ) 3.0 Hz, J ) 13.7, 1H, AB system), 2.38 (d, J ) 13.5 Hz, 1H, AB system), 2.10 (s, 3H), 1.97 (s, 3H), 1.73 (s, 9H), 1.39 (s, 9H), 1.38 (s, 9H), 1.37 (s, 9H), 1.05 (dd, J ) 1.7 Hz, J ) 12.0 Hz 1H), 0.85 (dd, J ) 1.8 Hz, J ) 13.5 Hz 1H); 13C NMR δ 160.6 (1C), 158.1 (C), 138.7 (C), 136.6 (C), 129.3 (CH), 129.0 (CH), 125.3 (C), 124.7 (CH), 124.0 (CH), 123.3 (C), 120.8 (C), 119.8 (CH), 75.8 (C), 75.6 (C), 66.1 (CH2), 63.2 (CH2), 51.2 (CH2), 50.9 (CH2), 46.5 (CH3), 45.4 (CH3), 35.4 (C), 34.1 (C), 35.2 (CH3), 32.8 (CH3), 31.9 (CH3), 30.6 (CH3). Anal. Calcd for C34H55ClN2O4Zr · 0.5pentane: C, 59.83; H, 8.12; N, 4.10. Found: C, 60.47; H, 8.62; N, 3.98. Lig2Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig2H2 (61.3 mg, 100%): 1H NMR δ 7.58 (d, J ) 2.5 Hz, 1H), 7.40 (d, J ) 2.4 Hz, 1H), 6.91 (d, J ) 2.5 Hz, 1H), 6.62 (d, J ) 2.6 Hz, 1H), 4.59 (d, J ) 13.2 Hz, 1H, AB system), 4.39 (d, J ) 13.5 Hz, 1H, AB system), 2.77 (d, J ) 13.4 Hz, 1H, AB system), 2.74 (td, J ) 3.3 Hz, J ) 13.6, 1H, AB system), 2.33 (d, J ) 13.6 Hz, 1H, AB system), 2.31 (td, J ) 3.3 Hz, J ) 13.2 1H, AB system), 2.12 (s, 3H), 1.95 (s, 3H), 1.71 (s, 9H), 1.43 (s, 9H), 1.36 (s, 9H), 1.36 (s, 9H), 0.83 (dd, J ) 1.8 Hz, J ) 13.4 1H, AB system), 0.79 (dd, J ) 1.9 Hz, J ) 13.5 1H, AB system); 13C NMR δ 158.0 (C), 156.0 (C), 139.0 (C), 136.8 (C), 129.5 (CH), 128.1 (C), 127.6 (CH) 125.9 (C), 124.5 (CH), 124.0 (CH), 123.3 (C), 120.1 (CH), 75.8 (C), 75.4 (C), 65.2 (CH2), 63.1 (CH2), 51.1 (CH2), 50.9 (CH2), 46.4 (CH3), 45.3 (CH3), 35.4 (C), 34.1 (C), 33.1 (CH3), 32.9 (CH3), 31.9 (CH3), 30.3 (CH3). Anal. Calcd for C34H54Cl2N2O4Zr: C, 56.96; H, 7.59; N, 3.91. Found: C, 57.55; H, 8.02; N, 3.70. Suitable crystals for X-ray analysis were obtained from cold pentane. Crystal data for Lig2Zr(O-tert-Bu)2: C39H66Cl2N2O4Zr; M ) 789.06; monoclinic; space group P21/c; a ) 15.1740(2) Å; b ) 15.2550(2) Å; c ) 36.9390(5) Å; β ) 94.8900(6)°; V ) 8519.5(2) Å3; T ) 110(2) K; Z ) 8; Dc ) 1.230 g cm-3; µ(Mo KR) ) 0.421 mm-1; R1 ) 0.0597 and wR2 ) 0.1408 for 11 540 reflections with I > 2σ(I); R1 ) 0.1255 and wR2 ) 0.1746 for all 20 086 unique reflections. CCDC 673842. Lig3Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig3H2 (67.0 mg, 99%): 1H NMR δ 7.72 (d, J ) 2.5 Hz, 1H), 7.67 (d, J ) 2.4 Hz, 1H), 6.91 (d, J ) 2.4 Hz, 1H), 6.78 (d, J ) 2.5 Hz, 1H), 4.59 (d, J ) 13.3 Hz, 1H, AB system), 4.38 (d, J ) 13.5 Hz, 1H, AB

Cohen et al. system), 2.78 (d, J ) 13.4 Hz, 1H, AB system), 2.72 (dt, J ) 3.2 Hz, J ) 13.7, 1H, AB system), 2.30 (d, J ) 13.6 Hz, 1H, AB system), 2.29 (dt, J ) 3.1 Hz, J ) 13.6, 1H, AB system), 2.12 (s, 3H), 1.94 (s, 3H), 1.72 (s, 9H), 1.43 (s, 9H), 1.39 (s, 9H), 1.35 (s, 9H), 1.02 (dd, J ) 3.3 Hz, J ) 10.4 Hz 1H), 0.81 (dd, J ) 3.3 Hz, J ) 13.3 Hz 1H); 13C NMR δ 157.9 (C), 157.6 (C), 138.6 (C), 136.8 (C), 135.0 (CH), 131.7 (CH), 126.3 (C), 124.5 (CH), 124.0 (CH), 123.2 (C), 114.9 (C), 107.3 (C), 76.3 (C), 75.8 (C), 65.2 (CH2), 63.1 (CH2), 51.1 (CH2), 50.8 (CH2), 46.3 (CH3), 45.5 (CH3), 35.4 (C), 34.1 (C), 33.1 (CH3), 33.0 (CH3), 31.9 (CH3), 30.2 (CH3). Anal. Calcd for C34H54Br2N2O4Zr · pentane: C, 53.35; H, 7.58; N, 3.19. Found: C, 52.42; H, 7.29; N, 3.48. Lig4Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig4H2 (71.9 mg, 90%): 1H NMR δ 8.13 (d, J ) 2.0 Hz, 1H), 7.58 (d, J ) 2.4 Hz, 1H), 6.98 (d, J ) 2.0 Hz, 1H), 6.92 (d, J ) 2.4 Hz, 1H), 4.61 (d, J ) 13.3 Hz, 1H, AB system), 4.34 (d, J ) 13.5 Hz, 1H, AB system), 2.78 (d, J ) 13.7 Hz, 1H, AB system), 2.70 (dt, J ) 3.2 Hz, J ) 13.7, 1H, AB system), 2.25 (d, J ) 13.6 Hz, 1H, AB system), 2.24 (dt, J ) 3.6 Hz, J ) 14.3, 1H, AB system), 2.11 (s, 3H), 1.91 (s, 3H), 1.72 (s, 9H), 1.44 (s, 9H), 1.38 (s, 9H), 1.33 (s, 9H), 0.99 (dd, J ) 1.9 Hz, J ) 13.4 Hz 1H), 0.75 (dd, J ) 2.0 Hz, J ) 13.5 Hz 1H); 13C NMR δ 160.5 (C), 157.9 (C), 146.0 (CH), 138.9 (C), 138.5 (CH), 136.8 (C), 125.7 (C), 124.5 (CH), 124.0 (CH), 123.2 (C), 92.1 (C), 77.2 (C), 76.4 (C), 75.8 (C), 65.2 (CH2), 63.1 (CH2), 51.1 (CH2), 50.8 (CH2), 46.2 (CH3), 45.8 (CH3), 35.4 (C), 34.1 (C), 33.2 (CH3), 33.1 (CH3), 31.9 (CH3), 30.2 (CH3). Anal. Calcd for C34H54I2N2O2Zr: C, 45.38; H, 6.05; N, 3.11. Found: C, 45.09; H, 6.12; N, 3.00. Lig5Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig5H2 (70.9 mg, 100%): 1H NMR δ 7.40 (d, J ) 2.5 Hz, 1H), 7.18 (d, J ) 2.0 Hz, 1H), 6.64 (d, J ) 2.5 Hz, 1H), 6.55 (d, J ) 2.0 Hz, 1H), 4.56 (d, J ) 13.3 Hz, 1H, AB system), 4.40 (d, J ) 13.5 Hz, 1H, AB system), 2.68 (d, J ) 13.3 Hz, 1H, AB system), 2.65 (dt, J ) 3.1 Hz, J ) 13.4, 1H, AB system), 2.36 (m, 6H,), 2.30 (s, 3H,), 2.18 (m, 3H), 2.06 (s, 3H), 2.04 (m, 3H), 1.85 (m, 3H), 1.45 (s, 3H), 1.43 (s, 9H), 1.35 (s, 9H), 1.00 (m, 1H), 0.90 (m, 1H); 13C NMR δ 158.3 (C), 156.2 (C), 137.6 (CH), 129.5 (CH), 128.4 (CH), 127.7 (CH), 127.6 (CH), 125.8 (C), 125.6 (C), 124.4 (C), 124.0 (C), 120.1 (C), 76.3 (C), 75.7 (C), 64.7 (CH2), 63.5 (CH2), 51.3 (CH2), 51.1 (CH2), 46.4 (CH3), 45.6 (CH3), 41.2 (CH2), 37.4 (CH2), 37.2 (C), 33.1 (CH3), 32.9 (CH), 32.8 (CH3), 29.6 (CH3), 22.5 (C), 20.9 (C). Anal. Calcd for C37H54Cl2N2O4Zr · pentane: C, 61.14; H, 8.06; N, 3.40. Found: C, 60.82; H, 8.11; N, 3.51. Lig6Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig6H2 (46.7 mg, 100%): 1H NMR δ 7.70 (m, 6H), 7.36 (d, J ) 2.6 Hz, 1H), 7.23 (d, J ) 1.9 Hz, 1H), 7.16 (m, 3H), 7.01 (m, 6H), 6.64 (d, J ) 1.8 Hz, 1H), 6.61 (d, J ) 2.6 Hz, 1H), 4.75 (d, J ) 13.6 Hz, 1H, AB system), 4.10 (d, J ) 13.5 Hz, 1H, AB system), 2.71 (d, J ) 13.7 Hz, 1H, AB system), 2.46 (dt, J ) 2.9 Hz, J ) 13.7, 1H, AB system), 2.17 (d, J ) 13.6 Hz, 1H, AB system), 2.14 (m, 1H), 2.13 (s, 3H), 1.6 (s, 9H), 1.06 (s, 3H), 1.00 (s, 9H), 0.83 (dd, J ) 2.1 Hz, J ) 12.0 Hz, 1H), 0.70 (dd, J ) 2.5 Hz, J ) 13.5 Hz 1H); 13 C NMR δ 157.9 (C), 156.4 (C), 134.7 (C), 133.8 (CH), 130.3 (CH), 129.5 (CH), 127.7 (CH), 127.0 (CH), 125.8 (C), 125.3 (CH), 124.9 (C), 124.3 (C), 119.9 (C), 76.6 (C), 75.7 (C), 64.9 (CH2), 64.1 (C), 63.1 (CH2), 51.0 (CH2), 50.9 (CH3), 45.3 (CH3), 33.2 (CH3), 32.6 (CH3). Anal. Calcd for C46H54Cl2O2N2Zr: C, 64.16; H, 6.32; N, 3.25. Found: C, 64.07; H, 6.71; N, 3.06. Lig7Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig7H2 (75 mg, 100%): 1 H NMR δ 7.56 (d, J ) 2.4 Hz, 1H), 7.41 (d, J ) 2.5 Hz, 1H), 6.87 (d, J ) 2.4 Hz, 1H), 6.71 (d, J ) 2.5 Hz, 1H), 4.62 (d, J ) 13.3 Hz, 1H, AB system), 4.48 (d, J ) 13.4 Hz, 1H, AB system), 2.99 (d, J ) 13.4 Hz, 1H, AB system), 2.67 (d, J ) 13.5 Hz, 1H,

C1-Symmetric Zirconium Salan Polymerization Catalysts AB system), 2.57 (dt, J ) 4.3 Hz, J ) 11.2, 1H), 2.26 (dt, J ) 4.2 Hz, J ) 11.6 1H), 2.23 (s, 3H), 2.15 (s, 3H), 1.75 (s, 9H), 1.49 (s, 9H), 1.44 (s, 9H), 1.36 (s, 9H), 1.28 (m, 2H), 1.03 (m, 2H), 0.35 (m, 4H); 13C NMR δ 158.4 (C), 156.8 (C), 138.8 (C), 136.3 (C), 129.8 (CH), 127.5 (CH), 126.3 (C), 124.3 (CH), 124.0 (CH), 123.5 (C), 120.1 (C), 76.5 (C), 75.9 (C), 60.9 (CH2), 59.2 (CH2), 57.1 (CH), 56.8 (CH), 40.1 (CH3), 39.4 (CH3), 35.4 (C), 34.1 (C), 33.1 (CH3), 32.8 (CH3), 31.8 (CH3), 30.3 (CH3), 23.8 (CH2), 23.7 (CH2), 21.2 (CH2), 21.1 (CH2). Anal. Calcd for C38H60Cl2N2O4Zr: C, 59.19; H, 7.84; N, 3.63. Found: C, 59.42; H, 8.03; N, 3.47. Suitable crystals for X-ray analysis were obtained from cold ether. Crystal data for rac-Lig7Zr(O-tert-Bu)2: C38H60Cl2N2O4Zr; M ) 771.00; monoclinic; space group P21/c; a ) 19.6465(4) Å; b ) 10.6398(2) Å; c ) 20.5229(6) Å; β ) 110.2014(8)°; V ) 4026.10(16) Å3; T ) 110(2) K; Z ) 4; Dc ) 1.272 g cm-3; µ(Mo KR) ) 0.444 mm-1; R1 ) 0.0645 and wR2 ) 0.1210 for 5678 reflections with I > 2σ(I); R1 ) 0.1322 and wR2 ) 0.1438 for all 9543 unique reflections. CCDC 673841. Lig8Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig8H2 (72.2 mg, 98%): 1H NMR δ 7.73 (d, J ) 2.4 Hz, 1H), 7.56 (d, J ) 2.4 Hz, 1H), 6.88 (d, J ) 2.7 Hz, 1H), 6.87 (d, J ) 2.7 Hz, 1H), 4.62 (d, J ) 13.3 Hz, 1H, AB system), 4.48 (d, J ) 13.5 Hz, 1H, AB system), 2.99 (d, J ) 13.4 Hz, 1H, AB system), 2.65 (d, J ) 13.5 Hz, 1H, AB system), 2.56 (dt, J ) 4.0 Hz, J ) 11.0, 1H), 2.23 (s, 3H), 2.22 (dt, J ) 4.0 Hz, J ) 11.6 1H), 2.13 (s, 3H), 1.75 (s, 9H), 1.49 (s, 9H), 1.43 (s, 9H), 1.36 (s, 9H), 1.25 (m, 2H), 1.00 (m, 2H), 0.30 (m, 4H); 13C NMR δ 158.4 (C), 158.1 (C), 138.8 (C), 136.3 (C), 135.3 (CH), 131.2 (CH), 126.7 (C), 124.3 (CH), 124.0 (CH), 123.5 (C), 114.6 (C), 107.2 (C), 76.5 (C), 76.0 (C), 60.9 (CH2), 59.3 (CH2), 57.1 (CH), 56.8 (CH), 40.0 (CH3), 39.6 (CH3), 35.4 (C), 34.1 (C), 33.1 (CH3), 32.9 (CH3), 31.8 (CH3), 30.3 (CH3), 23.8 (CH2), 23.7 (CH2), 21.2 (CH2), 21.1 (CH2). Anal. Calcd for C38H60Br2N2O4Zr · ether: C, 54.01; H, 7.55; N, 3.00. Found: C, 54.32 H, 7.91; N, 2.92. Suitable crystals for X-ray analysis were obtained from cold pentane. Crystal data for Lig8Zr(O-tert-Bu)2: C91H156Br2N2O8Zr2; M ) 1936.28; monoclinic; space group P21/n; a ) 17.9143(4) Å; b ) 15.1552(3) Å; c ) 19.4486(5) Å; β ) 113.2079(10)°; V ) 4852.92(19) Å3; T ) 110(2) K; Z ) 2; Dc ) 1.325 g cm-3; µ(Mo KR) ) 1.913 mm-1; R1 ) 0.0660 and wR2 ) 0.1295 for 6747 reflections with I > 2σ(I); R1 ) 0.1350 and wR2 ) 0.1534 for all 11 493 unique reflections. Lig9Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig9H2 (52.9 mg, 0.12 mmol) (80.1 mg, 99%): 1H NMR δ 7.56 (d, J ) 2.4 Hz, 1H), 7.41 (d, J ) 2.5 Hz, 1H), 6.87 (d, J ) 2.4 Hz, 1H), 6.71 (d, J ) 2.5 Hz, 1H), 4.62 (d, J ) 13.3 Hz, 1H, AB system), 4.48 (d, J ) 13.4 Hz, 1H, AB system), 2.99 (d, J ) 13.4 Hz, 1H, AB system), 2.67 (d, J ) 13.5 Hz, 1H, AB system), 2.57 (dt, J ) 4.3 Hz, J ) 11.2, 1H), 2.26 (dt, J ) 4.2 Hz, J ) 11.6 1H), 2.23 (s, 3H), 2.15 (s, 3H), 1.75 (s, 9H), 1.49 (s, 9H), 1.44 (s, 9H), 1.36 (s, 9H), 1.28 (m, 2H), 1.03 (m, 2H), 0.35 (m, 4H); 13C NMR δ 158.4 (C), 156.8 (C), 138.8 (C), 136.3 (C), 129.8 (CH), 127.5 (CH), 126.3 (C), 124.3 (CH), 124.0 (CH), 123.5 (C), 120.1 (C), 76.5 (C), 75.9 (C), 60.9 (CH2), 59.2 (CH2), 57.1 (CH), 56.8 (CH), 40.1 (CH3), 39.4 (CH3), 35.4 (C), 34.1 (C), 33.1 (CH3), 32.8 (CH3), 31.8 (CH3), 30.3 (CH3), 23.8 (CH2), 23.7 (CH2), 21.2 (CH2), 21.1 (CH2). Anal. Calcd for C38H60I2N2O4Zr · 2ether: C, 50.13; H, 7.32; N, 2.54. Found: C, 49.66; H, 7.05; N, 2.74. Suitable crystals for X-ray analysis were obtained from cold ether. Crystal data for rac-Lig6Zr(O-tert-Bu)2: C44H75I2N2O5.50Zr; M ) 1065.08; monoclinic; space group P21/n; a ) 17.9449(2) Å; b ) 15.2388(2) Å; c ) 19.1755(5) Å; β ) 112.2254(5)°; V ) 4854.11(11) Å3; T ) 110(2) K; Z ) 4; Dc ) 1.457 g cm-3; µ(Mo KR) ) 1.541 mm-1; R1 ) 0.0506 and wR2 ) 0.1299 for 8192 reflections with I > 2σ(I); R1 ) 0.0829 and wR2 ) 0.1674 for all 11 497 unique reflections.

Organometallics, Vol. 28, No. 5, 2009 1403 Lig10Zr(O-tert-Bu)2 was synthesized according to the procedure described above for Lig1Zr(O-tert-Bu)2 from Lig10H2 (48.0 mg, 99%): 1H NMR δ 8.11 (d, J ) 2.1 Hz, 1H), 7.18 (d, J ) 2.0 Hz, 1H), 7.00 (d, J ) 2.1 Hz, 1H), 6.54 (d, J ) 1.8 Hz, 1H), 4.56 (d, J ) 13.3 Hz, 1H, AB system), 4.33 (d, J ) 13.6 Hz, 1H, AB system), 2.67 (d, J ) 13.5 Hz, 1H, AB system), 2.61 (dt, J ) 3.6 Hz, J ) 13.6, 1H, AB system), 2.39 (m, 6H), 2.29 (d, J ) 13.5 Hz, 1H, AB system), 2.30 (s, 3H), 2.26 (dt, J ) 3.1 Hz, J ) 13.8, 1H, AB system), 2.22 (m, 3H), 2.10 (s, 3H), 2.09 (m, 3H), 1.86 (m, 3H), 1.46 (s, 9H), 1.33 (s, 9H), 0.95 (m, 1H), 0.82 (dd, 1H); 13 C NMR δ 160.3 (C), 158.1 (C), 145.9 (CH), 138.3 (CH), 137.5 (C), 125.5 (C), 123.7 (C), 92.1 (C), 77.0 (C), 76.3 (C), 75.6 (C), 64.6 (CH2), 64.4 (CH2), 51.1 (CH2), 51.0 (CH2), 46.1 (CH3), 45.9 (CH2), 41.1 (CH2), 37.3 (CH2), 37.1 (C), 33.0 (CH2), 32.7 (CH3), 29.5 (CH3). Anal. Calcd for C37H54I2N2O4Zr · pentane: C, 48.80; H, 6.22; N, 2.88. Found: C, 48.81; H, 6.36; N, 2.70. Suitable crystals for X-ray analysis were obtained from cold pentane. Crystal data for Lig10Zr(O-tert-Bu)2: C37H54I2N2O4Zr, C5H12; M ) 1007.99; triclinic; space group P1j; a ) 9.5665(2) Å; b ) 15.7916(4) Å; c ) 15.9554(4) Å; β ) 88.0187(13)°; V ) 2214.40(9) Å3; T ) 110(2) K; Z ) 2; Dc ) 1.512 g cm-3; µ(Mo KR) ) 1.682 mm-1; R1 ) 0.0495 and wR2 ) 0.1242 for 5390 reflections with I > 2σ(I); R1 ) 0.0737 and wR2 ) 0.1391 for all 7291 unique reflections. Synthesis of Lig1ZrBn2. Lig1H2 (50.0 mg, 0.11 mmol) was dissolved in 2 mL of toluene and added dropwise to a solution of ZrBn4 (50.1 mg, 0.11 mmol) in toluene. The solution was stirred at room temperature for 6 h. The solvent was removed under vacuum, and the product was washed with pentane (2 mL) to yield a yellow solid (52.7 mg, 62%): 1H NMR δ 7.61 (d, J ) 2.4 Hz, 1H), 7.06 (m, 6H), 6.87 (m, 2H) 6.85 (d, J ) 2.4 Hz, 2H), 6.83 (m, 2H), 6.74 (d, J ) 8.5 Hz, 1H), 6.64 (d, J ) 2.6 Hz, 1H), 4.08 (d, J ) 13.8 Hz, 1H, AB system), 3.43 (d, J ) 13.8 Hz, 1H, AB system), 2.60 (dt, J ) 3.1 Hz, J ) 13.8, 1H, AB system), 2.57 (d, J ) 10.2 Hz, 1H, AB system), 2.49 (d, J ) 13.9 Hz, 1H, AB system), 2.42 (d, J ) 9.6 Hz, 1H, AB system), 2.20 (dt, J ) 3.2 Hz, J ) 13.9, 1H, AB system), 2.08 (d, J ) 9.6 Hz, 1H, AB system), 1.95 (d, J ) 14.0 Hz, 1H, AB system), 1.93 (d, J ) 10.1 Hz, 1H, AB system), 1.76 (s, 9H), 1.67 (s, 3H), 1.57 (s, 3H), 1.37 (s, 9H), 0.83 (dd, J ) 2.1 Hz, J ) 13.5 1H, AB system), 0.66 (dd, J ) 2.4 Hz, J ) 13.6 1H, AB system); 13C NMR δ 158.7 (C), 156.7 (C), 147.1 (CH), 146.3 (CH), 141.3 (C), 137.1 (C), 129.8 (CH), 129.5 (C), 128.7 (CH), 128.5 (CH), 127.2 (C), 127.0 (C), 125.2 (C), 124.9 (CH), 124.3 (CH), 123.3 (C), 122.1 (CH), 119.4 (C), 65.0 (CH2) 64.4 (CH2), 64.2 (CH2), 62.1 (CH2), 52.6 (CH2), 54.3 (CH3), 44.3 (CH3), 35.4 (C), 34.2 (C), 31.7 (CH3), 30.2 (CH3). Lig2ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig2H2 (82.1 mg, 95%): 1H NMR δ 7.61 (d, J ) 2.4 Hz, 1H), 7.42 (m, 2H), 7.33 (d, J ) 2.5 Hz, 1H), 6.97 (m, 7H), 6.85 (d, J ) 2.4 Hz, 1H), 6.69 (m, 1H), 6.40 (d, J ) 2.5 Hz, 1H), 4.12 (d, J ) 13.8 Hz, 1H, AB system), 3.9 (d, J ) 13.8 Hz, 1H, AB system), 2.83 (d, J ) 8.1 Hz, 1H, AB system), 2.68 (d, J ) 8.2 Hz, 1H, AB system), 2.62 (dt, J ) 3.1 Hz, J ) 13.8, 1H, AB system), 2.53 (d, J ) 14 Hz, 1H, AB system), 2.24 (d, J ) 10.8 Hz, 1H, AB system), 2.15 (dt, J ) 3.04 Hz, J ) 13.8, 1H, AB system), 1.82 (d, J ) 14.1 Hz, 1H, AB system), 1.8 (s, 3H), 1.75 (s, 3H), 1.71 (s, 9H), 1.38 (s, 9H), 0.91 (d, J ) 10.8 Hz, 1H, AB system), 0.87 (dd, J ) 2.2 Hz, J ) 13.5 1H, AB system), 0.64 (dd, J ) 2.5 Hz, J ) 13.5 1H, AB system); 13C NMR δ 156.3, 154.6 (2C, C), 151.6 (1C, C), 141.5, 139.8, 137.2 (3C, C), 131.0, 129.9 (4C, CH), 129.2, (1C, C), 127.0, (2C, CH), 125.5, 125.3 (2C, CH), 125.0 (1C, C), 124.7 (1C, CH), 124.3 (1C, C), 122.6 (1C, C), 120.6, (1C, CH). Suitable crystals for X-ray analysis were obtained from cold ether. Crystal data for Lig2ZrBn2: C45.5H64Cl2N2O3.25Zr; M ) 853.11; orthorombic; space group Iba2; a ) 28.4943(3) Å; b ) 17.8980(3) Å; c ) 17.8230(6) Å; β ) 122.1201(7) V ) 9089.5(4) Å3; T ) 110(2) K; Z ) 8; Dc ) 1.247 g cm-3; µ(Mo KR) ) 0.399 mm-1; R1 ) 0.0524 and wR2 ) 0.1230

1404 Organometallics, Vol. 28, No. 5, 2009 for 4452 reflections with I > 2σ(I); R1 ) 0.0703 and wR2 ) 0.1324 for all 5493 unique reflections. CCDC 673843. Lig3ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig3H2 (88.1 mg, 99%): 1H NMR δ 7.65 (d, J ) 2.3 Hz, 1H), 7.60 (d, J ) 2.4 Hz, 1H), 7.45 (d, J ) 7.8 Hz, 2H), 7.16 (d, J ) 15.2 Hz, 2H), 6.98 (m, 6H), 6.85 (d, J ) 2.3 Hz, 1H), 6.67 (m, 1H), 6.57 (d, J ) 2.3 Hz, 1H), 4.13 (d, J ) 13.8 Hz, 1H, AB system), 3.11 (d, J ) 13.9 Hz, 1H, AB system), 2.88 (d, J ) 8.1 Hz, 1H, AB system), 2.71 (d, J ) 8.1 Hz, 1H, AB system), 2.61 (dt, J ) 3.1 Hz, J ) 13.8, 1H, AB system), 2.54 (d, J ) 13.9 Hz, 1H, AB system), 2.20 (d, J ) 10.9 Hz, 1H, AB system), 2.13 (dt, J ) 3.0 Hz, J ) 13.8, 1H, AB system), 1.84 (d, J ) 13.8 Hz, 1H, AB system), 1.77 (s, 3H), 1.76 (s, 3H), 1.70 (s, 9H), 1.38 (s, 9H), 0.92 (d, J ) 10.9 Hz, 1H, AB system), 0.86 (dd, J ) 3.1 Hz, J ) 13.4 1H, AB system), 0.64 (dd, J ) 2.5 Hz, J ) 13.5 1H, AB system); 13C NMR δ 156.0 (C), 155.7 (C), 151.5 (C), 141.5 (C), 139.9 (C), 137.2 (C), 134.7 (CH), 131.6 (CH), 131.0 (CH), 129.9 (CH), 128.4 (CH), 128.0 (C), 127.8 (CH), 125.3 (CH), 125.0 (CH), 124.7 (C) 124.2, (CH), 120.7, (CH), 114.3, (C), 109.9, (C), 65.2 (CH2), 64.5 (CH2), 61.5 (CH2), 60.8 (CH2), 53.1 (CH2), 52.5 (CH2), 45.2 (CH3), 44.5 (CH3), 35.3 (C), 34.3 (C), 31.7 (CH3), 30.1 (CH3). Lig4ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig4H2 (77.0 mg, 84%): 1H NMR δ 8.08 (d, J ) 1.5 Hz, 1H), 7.61 (d, J ) 1.7 Hz, 1H), 7.50 (d, J ) 7.4 Hz, 2H), 6.98 (m, 6H), 6.84 (d, J ) 1.7 Hz, 1H), 6.77 (d, J ) 1.2 Hz, 1H), 6.69 (m, 1H), 6.38 (d, J ) 7.1 Hz, 1H), 4.11 (d, J ) 13.8 Hz, 1H, AB system), 3.14 (d, J ) 13.9 Hz, 1H, AB system), 2.94 (d, J ) 8.1 Hz, 1H, AB system), 2.77 (d, J ) 8.3 Hz, 1H, AB system), 2.60 (dt, J ) 2.9 Hz, J ) 13.3, 1H, AB system), 2.52 (d, J ) 14.0 Hz, 1H, AB system), 2.19 (d, J ) 10.8 Hz, 1H, AB system), 2.11 (dt, J ) 2.36 Hz, J ) 13.8, 1H, AB system), 1.77 (s, 3H), 1.73 (s, 3H), 1.70 (s, 9H), 1.37 (s, 9H), 0.97 (d, J ) 10.7 Hz, 1H, AB system), 0.84 (dd, J ) 2.1 Hz, J ) 13.2 1H, AB system), 0.59 (dd, J ) 1.9 Hz, J ) 13.6 1H, AB system); 13C NMR δ 159.4 (C), 156.2 (C), 151.1 (C), 145.9 (CH), 141.5 (C), 140.4 (C), 138.4 (CH), 137.1 (C), 130.9 (CH), 129.9 (CH), 125.4 (C), 125.0 (CH), 124.6, (CH), 124.3 (C), 120.9 (CH), 90.7 (C), 80.2 (C), 65.1 (CH2), 64.6 (CH2) 61.5 (CH2), 60.1, (CH2), 53.0 (CH2), 52.5 (CH2), 45.2 (CH3), 44.7 (CH3), 37.9 (C), 35.3 (C), 31.7 (CH3), 30.2 (CH3). Lig5ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig5H2 (72.5 mg, 95%): 1H NMR δ 7.43 (d, J ) 7.6 Hz, 2H), 7.31 (d, J ) 2.5 Hz, 1H), 7.20 (d, J ) 1.4 Hz, 1H), 7.0-6.93 (m, 4H), 6.85 (d, J ) 7.4 Hz, 2H), 6.66 (t, J ) 7.4 Hz, 2H), 6.49 (d, J ) 1.2 Hz, 1H), 6.38 (d, J ) 2.4 Hz, 1H), 4.16 (d, J ) 13.7 Hz, 1H, AB system), 3.04 (d, J ) 14.0 Hz, 1H, AB system), 2.95 (d, J ) 7.9 Hz, 1H, AB system), 2.71 (d, J ) 8.0 Hz, 1H, AB system), 2.55 (dt, J ) 2.4 Hz, J ) 14.1, 1H, AB system), 2.40 (m, 6H), 2.30 (s, 3H), 2.22 (m, 3H), 2.02 (m, 3H), 1.87 (s, 3H), 1.83 (m, 3H), 1.73 (s, 3H), 0.81 (dd, J ) 2.3 Hz, J ) 14.1 1H, AB system), 0.70 (d, J ) 10.5 Hz, 1H, AB system), 0.68 (dd, J ) 2.4 Hz, J ) 13.2 1H, AB system); 13C NMR δ 156.7 (C), 154.5 (C), 152.4 (C), 138.9 (C), 138.2 (C), 131.3 (CH), 130.1 (CH), 127.6 (CH), 127.2 (CH), 126.7 (CH), 125.8 (C), 125.5 (CH), 123.7 (C), 122.5 (C), 120.5 (CH), 64.8 (CH2), 64.1 (CH2), 61.4 (CH2), 61.0 (CH2) 53.4 (CH2), 52.2 (CH2), 44.9 (CH3), 44.5 (CH3), 41.2 (CH2), 37.1 (CH2), 29.6 (CH), 29.4 (CH3), 20.9 (CH3). Lig6ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig6H2 (60.8 mg, 88%): 1H NMR δ 7.56 (m, 4H), 7.32 (d, J ) 2.6 Hz, 1H), 7.29 (d, J ) 1.83 Hz, 1H), 7.19-6.99 (m, 15H), 6.92 (d, J ) 7.3 Hz, 2H), 6.8 (d, J ) 7.2 Hz, 2H), 6.61 (d, J ) 7.5 Hz, 2H), 6.51 (d, J ) 1.8 Hz, 1H), 6.49 (d, J ) 2.6 Hz, 1H), 2.32 (d, J ) 3.0 Hz, J ) 13.8 Hz, 1H, AB system), 2.26 (d, J ) 14.2 Hz, 1H, AB system), 2.16 (d, J ) 9.9 Hz, 1H, AB system), 2.10 (s, 3H), 2.08 (s, 3H), 2.05 (d, J ) 10.3 Hz, 1H, AB system), 2.04 (d, J ) 10.3 Hz, 1H, AB system), 2.03 (m, 1H), 1.51 (s, 3H), 0.67 (dd, J ) 2.3 Hz, J ) 13.2, 1H, AB system), 0.60 (dd, J ) 2.6 Hz, J ) 13.5 1H, AB system); 13C NMR δ 157.0

Cohen et al. (C), 154.7 (C), 151.6 (C), 142.6 (CH), 134.6 (C), 133.8 (CH), 129.9 (CH), 129.1 (CH), 128.6 (CH), 127.8 (CH), 127.3 (CH), 126.3 (CH), 125.9 (CH), 125.4 (C), 124.5 (C), 123.3 (C), 122.6 (C), 120.4 (CH), 70.5 (CH2) 67.1 (CH2), 63.9 (C), 63.0 (CH2), 62.5 (CH2), 52.6 (CH2), 52.4 (CH2), 44.0 (CH3), 43.6 (CH3), 20.7 (CH3). Suitable crystals for X-ray analysis were obtained from cold toluene. Crystal data for Lig6ZrBn2: C52H50Cl2N2O2Zr; 1.5(C7H8) M ) 1034.76; orthorombic; space group Pbca; a ) 14.7085(2) Å; b ) 25.8794(3) Å; c ) 27.7465(5) Å; β ) 90.00°; V ) 10561.6(3) Å3; T ) 110(2) K; Z ) 8; Dc ) 1.302 g cm-3; µ(Mo KR) ) 0.355 mm-1; R1 ) 0.0436 and wR2 ) 0.0984 for 6301 reflections with I > 2σ(I); R1 ) 0.0759 and wR2 ) 0.1135 for all 8882 unique reflections. Lig7ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig7H2 (50 mg, 57%): 1H NMR δ 7.59 (d, J ) 2.3 Hz, 1H), 7.51 (d, J ) 7.3 Hz, 1H), 7.35 (d, J ) 2.5 Hz, 2H), 7.21 (t, J ) 7.5 Hz, 3H), 7.04 (m, 5H), 6.78 (d, J ) 2.3 Hz, 1H), 6.49 (d, J ) 2.5 Hz, 1H), 4.04 (d, J ) 13.9 Hz, 1H, AB system), 3.26 (d, J ) 14.0 Hz, 1H, AB system), 2.93 (d, J ) 9.1 Hz, 1H, AB system), 2.89 (d, J ) 9.1 Hz, 1H, AB system), 2.75 (d, J ) 6.97 Hz, 1H, AB system), 2.73 (d, J ) 7.0 Hz, 1H, AB system), 2.69 (d, J ) 10.7 Hz, 1H, AB system), 2.87 (d, J ) 14.1, 1H, AB system), 1.98 (m, 4H), 1.88 (s, 3H), 1.80 (s, 3H), 1.77 (s, 9H), 1.40 (m, 2H), 1.34 (s, 9H), 0.23 (m, 2H), 0.11 (m, 2H); 13C NMR δ 157.2, 150.9, 141.7 (3C, C), 129.9, 129.6, 129.5, 128.8, 128.7, 128.5, 128.4, 127.9, 126.9 (9C, CH), 125.7 (1C, C), 125.1, 124.6, 123.4, 121.3 (4C, CH), 67.5, 67.1, 59.8 (3C, CH2), 58.6, 57.7 (2C, CH), 56.9 (1C, CH2), 38.6, 37.9 (2C, CH3), 34.4, 32.1 (2C, C), 31.9, 30.4 (2C, CH3), 23.9, 23.7, 21.3, 21.1 (4C, CH2). Lig8ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig8H2 (52.6 mg, 73%): 1H NMR δ 7.69 (d, J ) 2.4 Hz, 1H), 7.59 (d, J ) 2.4 Hz, 1H), 7.51 (d, J ) 7.2 Hz, 2H), 7.15 (m, 4H), 7.02 (m, 4H), 6.78 (d, J ) 2.3 Hz, 1H), 6.73 (m, 2H), 6.67 (d, J ) 2.4 Hz, 1H), 4.04 (d, J ) 13.9 Hz, 1H, AB system), 2.95 (d, J ) 15.7 Hz, 1H, AB system), 2.93 (d, J ) 15.7 Hz, 1H, AB system), 2.76 (d, J ) 14.0 Hz, 1H, AB system), 2.65 (d, J ) 10.7 Hz, 1H, AB system), 2.26 (d, J ) 14.2 Hz, 1H, AB system), 1.99 (m, 2H), 1.84 (s, 3H), 1.82 (s, 3H), 1.76 (s, 9H), 1.75 (m, 4H), 0.24 (m, 4H); 13C NMR δ 156.9 (C), 150.9 (C), 144.2 (C), 141.5 (C), 137.6 (C), 136.7 (C), 135.1 (C), 131.2 (C), 129.5 (CH), 129.3 (CH), 129.1 (CH), 126.7 (CH), 126.0 (CH), 124.4 (CH), 124.3 (CH), 123.4 (C), 121.0 (C), 114.1 (C), 110.0 (C), 66.3 (CH2), 64.9 (CH2), 59.6 (CH2), 58.3 (CH) 57.5 (CH), 56.7 (CH), 38.3 (CH3), 37.9 (CH3), 35.3 (C), 34.2 (C), 31.7 (CH3), 30.2 (CH3), 23.6 (CH2), 23.5 (CH2), 21.0 (CH2), 20.8 (CH2). Lig9ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig9H2 (52.6 mg, 73%): 1H NMR δ 8.11 (d, J ) 2.0 Hz, 1H), 7.58 (d, J ) 2.4 Hz, 1H), 7.54 (m, 2H), 7.20 (m, 4H), 7.04 (m, 3H), 6.96 (m, 2H), 6.87 (d, J ) 2.0 Hz, 1H), 6.77 (d, J ) 2.4 Hz, 1H), 6.75 (m, 1H), 4.02 (d, J ) 13.8 Hz, 1H, AB system), 3.30 (d, J ) 13.9 Hz, 1H, AB system), 3.02 (d, J ) 10.3 Hz, 1H, AB system), 3.00 (d, J ) 9.6 Hz, 1H, AB system), 2.74 (d, J ) 13.9 Hz, 1H, AB system), 2.64 (d, J ) 10.7 Hz, 1H, AB system), 2.32 (td, J ) 4.4 Hz, J ) 11.5 Hz, 1H, AB system), 2.26 (d, J ) 14.1 Hz, 1H, AB system), 1.84 (s, 3H), 1.82 (s, 3H), 1.76 (s, 9H), 1.66 (d, J ) 10.7 Hz, 1H, AB system), 1.40 (m, 2H), 1.32 (s, 9H), 1.30 (m, 3H), 0.24 (m, 4H); 13C NMR δ 170.56 (C), 160.3 (C), 157.1 (C), 150.7 (C), 146.5 (CH), 144.9 (C), 141.8 (C), 138.2 (CH), 136.9 (C), 129.6 (CH), 129.5 (CH), 127.1 (CH), 125.6 (CH), 125.1 (CH), 124.5 (CH), 123.5 (CH), 121.4 (CH), 91.0 (C), 80.5 (C), 67.8 (CH2), 66.6 (CH2), 59.8 (CH2), 58.5 (CH), 57.7 (CH2), 57.0 (CH2), 38.5 (CH3), 38.4 (CH3), 35.5 (C), 34.4 (C), 31.9 (CH3), 30.5 (CH3), 23.8 (CH2), 23.7 (CH2), 21.4 (CH2), 21.2 (CH2). Lig10ZrBn2 was synthesized according to the procedure described above for Lig1ZrBn2 from Lig10H2 (55.3 mg, 100%): 1H NMR δ 8.10 (d, J ) 2.2 Hz, 1H), 7.53 (d, J ) 7.5 Hz, 2H), 7.20 (m, 2H), 7.12-6.93 (m, 4H), 6.85 (d, J ) 7.5 Hz, 2H), 6.74 (d, J ) 1.8 Hz, 1H), 6.67 (m, 2H), 6.47 (d, J ) 1.5 Hz, 1H), 4.15 (d, J ) 13.6 Hz,

C1-Symmetric Zirconium Salan Polymerization Catalysts 1H, AB system), 3.11 (d, J ) 14.0 Hz, 1H, AB system), 3.09 (d, J ) 8.0 Hz, 1H, AB system), 2.77 (d, J ) 8.2 Hz, 1H, AB system), 2.73 (d, J ) 7.7 Hz, 1H, AB system), 2.52 (dt, J ) 2.2 Hz, J ) 12.4, 1H, AB system), 2.52-2.39 (m, 6H), 2.31 (s, 3H), 2.29-2.15 (m, 3H), 2.07-1.94 (m, 3H), 1.84 (s, 3H), 1.81-1.77 (m, 3H), 1.74 (s, 3H), 0.79 (d, J ) 10.8 Hz, AB system), 0.77 (d, J ) 10.8 Hz, 1H, AB system), 0.63 (dd, J ) 2.3 Hz, J ) 13.5 1H, AB system); 13C NMR δ 159.9 (C), 152.5 (C), 140.19 (C), 138.9 (CH), 131.7 (CH), 130.5 (CH), 129.7 (CH), 129.6 (CH), 127.4 (CH), 127.2 (CH), 126.5 (C), 126.0 (CH), 126.0 (C), 121.2 (C), 80.7 (C), 65.4 (CH2), 65.2 (CH2), 62.2 (CH2), 62.1 (CH2), 53.9 (CH2) 52.8 (CH2), 45.5 (CH3), 45.2 (CH3), 41.5 (CH), 37.8 (CH2), 30.1 (CH), 29.9 (CH3), 21.4 (C). General Procedure for the Polymerization of Neat 1-Hexene. B(C6F5)3 (1-2 equiv) was dissolved in ca.1 mL of 1-hexene and added to a stirred solution of the corresponding complexes, Lig1-11Zr(Bn)2 (11 µmol), in 1-hexene. The resulting mixture was

Organometallics, Vol. 28, No. 5, 2009 1405 stirred until the resulting polymer solution had become viscous, and the remaining 1-hexene was removed under vacuum, yielding poly(1-hexene) as a yellow sticky oil.

Acknowledgment. We thank the Israel Science Foundation and the U.S.-Israel Binational Science Foundation for financial support. We thank Dvora Reshef for technical assistance. Supporting Information Available: X-ray crystallographic files in CIF format for the structure determinations of complexes Lig8Zr(O-tert-Bu)2, Lig9Zr(O-tert-Bu)2, Lig10Zr(O-tert-Bu)2, and Lig6ZrBn2. This material is available free of charge via the Internet at http://pubs.acs.org. OM801058W

C1-Symmetric Zirconium Complexes of [ONNOâ²]-Type Salan Ligands

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