Synthesis and Reactivity of Coordination and Six-Membered

May 28, 2010 - Cyclometalated Platinum Complexes Containing a Bulky Diimine Ligand. Craig M. ... †Department of Chemistry, Bard College, P.O. Box 50...
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Organometallics 2010, 29, 2676–2684 DOI: 10.1021/om100068j

Synthesis and Reactivity of Coordination and Six-Membered, Cyclometalated Platinum Complexes Containing a Bulky Diimine Ligand Craig M. Anderson,*,† Margarita Crespo,*,‡ and Joseph M. Tanski§ †

Department of Chemistry, Bard College, P.O. Box 5000, Annandale-on-Hudson, New York 12504, Departament de Quı´mica Inorg anica, Facultat de Quı´mica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain, and §Department of Chemistry, Vassar College, 124 Raymond Avenue, Box 601, Poughkeepsie, New York 12604

‡

Received January 27, 2010

The reaction of [Pt2Me4(μ-SMe2)2] with ligand (9-C14H9)CHdNCH2CH2NdCH(9-C14H9) (L) gives initially the platinum(II) complex [PtMe2{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 1, which contains a chelate dinitrogen ligand. Compound 1 was reacted with MeI to give the related sixcoordinate platinum(IV) compound [PtMe3I{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 2, by oxidative addition. Compound 1, when refluxed in toluene, gave the monometalated complex [PtMe{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}], 3, with a six-membered, cyclometalated, anthryl ring. When compound 1 was reacted with acetyl chloride, the dicyclometalated compound [Pt{(9-C14H8)CHdNCH2CH2NdCH(9-C14H8)}], 4, with two six-membered cyclometalated anthryl rings, was formed. Similarly, cis-[PtCl2(dmso)2] was reacted with ligand L to afford the platinum(II) compound [PtCl2{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 5. This compound, when left in solution at room temperature, gave the monometalated compound [PtCl{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}], 6, but under no conditions tried was the dimetalated species obtained. The structures of [PtCl2{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 5, [PtMe3I{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 2, and [PtCl{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}], 6, were determined by X-ray diffraction. Introduction Dimethylplatinum(II) complexes containing bidentate nitrogen donor ligands have been extensively explored in relation to oxidative addition of alkyl halides1 and to protonation processes involving hydrido-platinum(IV) intermediates.2 As reported for ligands containing two nitrogen donor atoms that are part of nitrogen heterocycles3 as well as for diimines with the general formula ArNdC(R)-C(R)dNAr,4 the *Corresponding authors. (C.M.A.) E-mail: [email protected]. Phone: 845-752-2356. Fax: 845-752- 2339. (M.C.) E-mail: margarita.crespo@ qi.ub.es. Phone: 34934039132. Fax: 34934907725. (1) Rendina, L. M.; Puddephatt, R. J. Chem. Rev. 1997, 97, 1735. (2) (a) Hill, G. S.; Rendina, L. M.; Puddephatt, R. J. Organometallics 1995, 14, 4966. (b) Hinman, J. G.; Baar, C. A.; Jennings, M. C.; Puddephatt, R. J. Organometallics 2000, 19, 563. (c) Johansson, L.; Tilset, M. J. Am. Chem. Soc. 2001, 123, 739. (d) Prokopchuk, E. M.; Puddephatt, R. J. Organometallics 2003, 22, 787. (3) (a) Song, D.; Wang, S. Organometallics 2003, 22, 2187. (b) Zhang, F.; Kirby, C. W.; Hairsine, D. W.; Jennings, M. C.; Puddephatt, R. J. J. Am. Chem. Soc. 2005, 127, 14196. (c) Zhao, S. B.; Song, D.; Jia, W. L.; Wang, S. Organometallics 2003, 24, 3290. (d) Zhao, S. B.; Wu, G.; Wang, S. Organometallics 2006, 25, 5979. (e) Britovsek, G. J. P.; Taylor, R. A.; Sunley, G. J.; Law, D. J.; White, A. J. P. Organometallics 2006, 25, 2074. (4) (a) Johansson, L.; Ryan, O. B.; Tilset, M. J. Am. Chem. Soc. 1999, 121, 1974. (b) Johansson, L.; Tilset, M.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 2000, 122, 10846. (c) Johansson, L.; Ryan, O. B.; Rømming, C.; Tilset, M. J. Am. Chem. Soc. 2001, 123, 6579. (d) Zhong, H. A.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 2002, 124, 1378. (e) Heyduk, A. F.; Driver, T. G.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 2004, 126, 15034. (f) Gerdes, G.; Chen, P. Organometallics 2003, 23, 3031. (g) Driver, T. G.; Day, M. W.; Labinger, J. A.; Bercaw, J. E. Organometallics 2005, 24, 3644. (h) Owen, J. S.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 2006, 128, 2005. (i) Driver, T. G.; Williams, T. J.; Labinger, J. A.; Bercaw, J. E. Organometallics 2007, 26, 294. pubs.acs.org/Organometallics

Published on Web 05/28/2010

protonation reaction generates platinum species that activate C-H bonds under mild conditions. Recent advances in organometallic chemistry and homogeneous catalysis have emphasized the important role of steric effects of ligands for square-planar complexes. In particular, bulky substituents on diimine ligands influence processes such as intermolecular C-H activation,4 oxidative addition reactions,5 and catalyzed olefin polymerization.6 In addition, dimethylplatinum(II) compounds with appropriately designed bidentate nitrogen donor ligands are adequate substrates for intramolecular C-H bond activation leading to terdentate [C,N,N0 ] systems.7 In order to gain information on the influence of the supporting ligand, previously we have studied the reactivity of platinum(II) compounds containing amine-imine ligands such as Me2NCH2CH2NdCHAr in which Ar is a bulky naphthyl,8 anthryl, or phenanthryl9 group. (5) Gonsalvi, L.; Gaunt, J. A.; Adams, H.; Castro, A.; Sunley, G. J.; Haynes, A. Organometallics 2003, 22, 1047. (6) Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100, 1169. (7) (a) Anderson, C. M.; Crespo, M.; Jennings, M. C.; Lough, A. J.; Ferguson, G.; Puddephatt, R. J. Organometallics 1991, 10, 2672. (b) Baar, C. R.; Jenkins, H. A.; Vittal, J. J.; Yap, G. P. A.; Puddephatt, R. J. Organometallics 1998, 17, 2805. (c) Baar, C. R.; Hill, G. S.; Vittal, J. J.; Puddephatt, R. J. Organometallics 1998, 17, 32. (d) Anderson, C.; Crespo, M. J. Organomet. Chem. 2004, 689, 1496. (8) (a) Crespo, M.; Font-Bardia, M.; Perez, S.; Solans, X. J. Organomet. Chem. 2002, 642, 171. (b) Crespo, M.; Evangelio, E.; Font-Bardia, M.; Perez, S.; Solans, X. Polyhedron 2003, 22, 3363. (9) (a) Crespo, M.; Evangelio, E. J. Organomet. Chem. 2004, 689, 1956. (b) Bosque, R.; Crespo, M.; Evangelio, E.; Font-Bardia, M.; Solans, X. J. Organomet. Chem. 2005, 690, 2062. r 2010 American Chemical Society

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Oxidative Addition Reactions. Ligand (9-C14H9)CHdNCH2CH2NdCH(9-C14H9) (L) was prepared from the condensation reaction of anthracene-9-aldehyde with ethylenediamine (molar ratio 2: 1) carried out in toluene at room temperature. The resulting imine was characterized by 1H NMR spectroscopy and mass spectrometry (MS), and the data were in good agreement with those previously reported.11,12 The reaction of [Pt2Me4( μ-SMe2)2] with ligand L in acetone solution produced the compound [PtMe2{(9-C14H9)CHd NCH2CH2NdCH(9-C14H9)}], 1, in which the imine acts as a bidentate [N,N] ligand. Compound 1 was characterized by elemental analyses, 1H NMR, and MS. In the 1H NMR spectrum, one resonance coupled with 195Pt is seen in the methyl region. The coordination of the ligand through both nitrogen atoms is confirmed by the existence of coupling of both imine protons to the platinum center. Compound 1 is an appropriate substrate to study whether oxidative addition of methyl iodide is possible or not when bulky groups are present. Upon addition of methyl iodide to an orange dichloromethane solution of compound 1, the color of the solution faded, and upon workup of the final solution, the corresponding platinum(IV) compound [PtMe3I{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 2, was isolated in high yield. The new compound shown in the Scheme 1 was characterized by elemental analysis, MS, and 1H NMR spectra. The NMR of compound 2 shows two distinct methylplatinum resonances coupled to platinum as expected. The values of the 2J(Pt-H) coupling constants are in the range expected for a fac-PtMe3 geometry13 and smaller (72.8-75.6 Hz) than that of the corresponding platinum(II) compound

(88.8 Hz), which is consistent with the higher oxidation state of platinum. The resonance at higher field, with an integration of six hydrogen atoms (δ = -0.17 ppm), is assigned to the equatorial methyl groups trans to the imine nitrogen atoms, and its low chemical shift might be related to the proximity of these methyl ligands to the anthracene group.9 The resonance at 0.53 ppm is assigned to the axial methyl trans to the iodo ligand. In agreement with coordination through both nitrogen atoms, the imine protons are also coupled to platinum, and the J(H-Pt) value (31.2 Hz) indicates an E conformation14 of both CdN bonds in the platinum(IV) compounds initially formed.15 A 2D-NOESY experiment confirms the E conformation about the imine groups since a cross-peak is observed between the imine and the methylene protons. When compound 2 was allowed to stand in solution for 24 h, in addition to the (E,E) isomer initially formed, two new isomers, (E,Z) and (Z,Z), are formed in the ratio 2-(E,E): 2-(E,Z):2-(Z,Z) = 3.0:1.0:1.2. Within 48 h, the amount of isomer (E,E) decreases while that of (Z,Z) increases, the ratio being 2-(E,E):2-(E,Z):2-(Z,Z)=1.4:1.0:2.0. Crystals of the (E,Z) isomer were characterized crystallographically (see below). For isomer (E,Z), three distinct methyl and two distinct imine resonances are observed in the proton NMR spectrum. The J(H-Pt) values for the imine groups are rather different (33.0 and 18.5 Hz), in agreement with the reduced values expected for a Z conformation. Moreover, only one imine resonance (δ = 9.69 ppm) shows a cross-peak with a resonance corresponding to two equivalent methylene protons (δ = 4.01 ppm). For isomer (Z,Z), two distinct methylplatinum resonances coupled to platinum are observed. The resonance at higher field integrating three hydrogen atoms (δ = 1.36 ppm) is assigned to the axial methyl group trans to the iodo, and the resonance at 1.63 ppm integrating six hydrogen atoms is assigned to the equatorial methyl groups trans to the nitrogen atoms. The large downfield shift observed for the equatorial methyl groups resonances in (Z,Z) (δ = 1.63 ppm) when compared to that of the (E,E) isomer (δ=-0.17 ppm) is related to the change in the position of the anthracene groups that places them away from the equatorial methyl ligands. In agreement with a (Z,Z) conformation, the two imine protons are equivalent and the observed coupling to platinum is 18.5 Hz. These results indicate that oxidative addition of methyl iodide is not inhibited by the presence of bulky anthryl groups. However, due to the increased bulk of octahedral platinum(IV) versus square-planar platinum(II) centers, this reaction is followed by isomerization of both imine groups in order to reduce the steric crowding. In most cases, the oxidative addition of alkyl halides to organo-platinum(II) complexes gives trans stereochemistry, although subsequent isomerization can yield products that appear to arise from cis-oxidative addition.13,16 In order to analyze the stereochemistry of the platinum(IV) compound initially formed, the oxidative addition of CD3I to compound 1 in CDCl3 solution was monitored by 1H NMR spectroscopy at low temperature.

(10) Costa, A. M.; Jimeno, C.; Gavenosis, J.; Carroll, P. J.; Walsh, P. J. J. Am. Chem. Soc. 2002, 124, 6929. (11) Zhang, G. Q.; Yang, G. Q.; Zhu, L. N.; Chen, Q. Q.; Ma, J. S. Sensors Actuators B 2006, 114, 995. (12) Zhang, G. Q.; Yang, G. Q.; Yang, L. Y.; Chen, Q. Q.; Ma, J. S. Eur. J. Inorg. Chem. 2005, 1919. (13) Crespo, M.; Puddephatt, R. J. Organometallics 1987, 6, 2548.

(14) E/Z labels are used in this paper by considering only the organic portions of the molecule, not the Pt atom, in order to be consistent with the free ligand designation. (15) Creber, M. L.; Orrell, K. G.; Osbourne, A. G.; Sik, V.; Coles, S. J.; Hibbs, D. E.; Hursthouse, M. B. Inorg. Chim. Acta 2000, 299, 209. (16) von Zelewsky, A.; Suckling, A. P.; Stoeckli-Evans, H. Inorg. Chem. 1993, 32, 4585.

Chart 1

In this work, we focus on the reactivity of the compound [PtMe2(ArCHdNCH2CH2NdCHAr)] (1) containing a diimine ligand L in which both aryl groups are bulky 9-anthryl groups. This ligand differs from the most widely used diimines of general formula ArNdC(R)-C(R)dNAr in the fact that both imine moieties are not part of the chelate-metallocycle ring formed upon [N,N] coordination to the metal (see structures a and b in Chart 1). Ligand L has been used to activate an enantiopure catalyst,10 and the related diamine obtained through reduction has been found to be a potential fluorescent sensor for Zn2þ, while its silver(I) and palladium(II) derivatives display interesting photophysical properties.11,12

Results

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Anderson et al. Scheme 1. 14

At -40 °C, the oxidative addition was complete, and according to the integration, the ratio of the signals corresponding to the equatorial and axial methyl groups was ca. 3.3, which suggests that the amount of compound 2a (containing an axial CD3) is larger than that of compound 2b (in which CD3 is in an equatorial position). Upon heating the reaction mixture, the ratio of the signals Meeq:Meax decreases to a final value of ca. 2.0 attained at 0 °C and statistically indicative of a random distribution of CD3 ligands into equatorial and axial positions. These results

point to initial trans oxidative addition of CD3I followed by scrambling of the methyl groups in a process depicted in Scheme 2.17 It has been reported that scrambling may take place at room temperature, as for [PtMe2bipy],13 or even at low temperature along with the oxidative addition, as for [PtMe2(di-2-pyridylamine)],17 depending on the relative rates of the rearrangement of the ionic five-coordinate (17) Zhang, F.; Prokopchuk, E. M.; Broczkowski, M. E.; Jennings, M. C.; Puddephatt, R. J. Organometallics 2006, 25, 1583.

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Organometallics, Vol. 29, No. 12, 2010 Scheme 2

intermediate [PtMe2(CD3)(NN)]I and the iodide coordination steps. Cyclometalation Reactions. Cycloplatination reactions with loss of CH4 have been reported for dimethylplatinum(II) compounds containing imine or diimine ligands,7 and these reactions often proceed at room temperature. Compound 1, however, is stable in solution at room temperature, and this can be related to the fact that formation of six-membered metallacycles is less facile than formation of the more common five-membered analogues.18 Nevertheless, when compound 1 was refluxed in toluene for 1 h, metalation of one of the anthryl substituents was achieved, leading to compound [PtMe{(9C14H9)CHdNCH2CH2NdCH(9-C14H8)}], 3, with release of methane. Compound 3 was characterized by elemental analysis, MS, and NMR spectra. The complexity of the 1H NMR spectrum is consistent with formation of a monocyclometalated compound with two nonequivalent moieties of the ligand. In addition, the presence of a single methyl-platinum resonance and of 13 cross-peaks in the aromatic region of the 1 H-13C heterocorrelation spectrum support the structure proposed in Scheme 3. 1H-1H COSY and NOESY spectra allow for assignment of the resonances of both moieties of the molecule. Each imine proton shows a cross-peak with one methylene group, thus suggesting an E conformation around both CHdN moieties. When the reaction time was increased to 4 h, formation of compound 4 in which both anthryl groups are metalated, was observed. Within 24 h in refluxing toluene, a mixture of the compounds mono- 3 and dimetalated 4 with a ratio 1:2 was obtained. Moreover, compound 4, in which the ligand behaves as a dianionic [C,N,N,C] tetradentate system including two six-membered metallacycles, was unexpectedly obtained in the reaction of compound 1 with one equivalent of (18) (a) Omae, I. Organometallic Intramolecular Coordination Compounds; Elsevier: Amsterdam, 1986. (b) Minghetti, G.; Doppiu, A.; Stoccoro, S.; Zucca, A.; Cinellu, M. A.; Manassero, M.; Sansoni, M. Eur. J. Inorg. Chem. 2002, 431. (c) Zucca, A.; Stoccoro, S.; Cinellu, M. A.; Minghetti, G.; Manassero, M.; Sansoni, M. Eur. J. Inorg. Chem. 2002, 3336.

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acetyl chloride carried out at room temperature in dichloromethane-methanol solution. The purpose of this reaction was to study the protonation process of compound 1 using acetyl chloride as a source of anhydrous HCl. The mechanism of the protonolysis reactions of analogous dimethylplatinum(II) compounds has been studied and shown to consist in an oxidative addition leading to hydrido-platinum(IV) intermediates.2a According to previous results19 a final compound in which a methyl is replaced by a chloro ligand was expected; however compound 4 was obtained in a clean and fast reaction without evidence of formation of other platinum species. In view of these results, the protonation of compound 1 with CF3CO2H was also tested. Initial attempts using equimolar amounts of the reactants produced dark red solutions in which only phenanthrene-9-aldehyde could be unambiguously characterized. When a trace amount of CF3CO2H was added to a solution of 1 at low temperature, the NMR analysis of the resulting solution indicated the presence, along with unreacted compound 1 and free ligand, of small amounts of a compound that could be tentatively assigned as [PtMe2H(CF3CO2)L]. This type of compound has been reported and characterized in the literature;2,17 however in this case we could not detect the presence of a hydrido ligand by proton NMR spectroscopy even though we scanned a region up to -30 ppm. Furthermore, since further reaction proceeds with formation of large amounts of aldehyde, the compound could not be adequately characterized. As a whole, these results indicated that the dimetalated compound 4 is not formed under these reaction conditions. Compound [Pt{(9-C14H8)CHdNCH2CH2NdCH(9-C14H8)}], 4, was characterized by elemental analysis, MS, and NMR spectra. Due to the symmetry of the molecule, the 1H NMR spectrum is simplified compared to that of compound 3. The presence of eight cross-peaks due to aromatic C-H in the 1H-13C gHSQC spectrum is consistent with double cyclometalation. The aromatic protons were assigned with the aid of 1H-1H COSY and NOESY spectra. The latter shows cross-peaks of the imine proton with both the methylene and one aromatic proton (H8). The proton adjacent to the metalation site (H1) is upfield shifted due to the proximity of the other anthryl group and is coupled to platinum (J(H-Pt) = 67.6 Hz). The imine proton at 10.06 ppm is also coupled to platinum with a coupling constant of 36.0 Hz. This relatively low value is in the range obtained for previously reported six-membered metallacycles9a and similar to that obtained for the metalated fragment in compound 3 (J(H-Pt) = 34.5 Hz). Since the straightforward cyclometalation of both anthryl rings upon reaction of compound 1 with acetyl chloride might be related to replacement of methyl for chloro ligands, the synthesis of compound [PtCl2{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}], 5, was also carried out. This compound could be easily obtained from cis-[PtCl2(dmso)2] and ligand L following previously reported procedures for analogous compounds.20 Compound 5 was characterized by usual techniques, and a (Z,Z) conformation was assumed on the basis of the cross-peak observed between the methylene (19) (a) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411. (b) Crespo, M.; Granell, J.; Solans, X.; Font-Bardia, M. Organometallics 2002, 21, 5140. (20) (a) Crespo, M.; Font-Bardia, M.; Granell, J.; Martinez, M.; Solans, X. Dalton Trans. 2003, 3763. (b) Capape, A.; Crespo, M.; Granell, J.; Font-Bardia, M.; Solans, X. J. Organomet. Chem. 2005, 690, 4309.

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Anderson et al. Scheme 3

resonance and an aromatic signal observed at 7.86 ppm. Previous studies for analogous compounds indicate that the higher bulk of chloro versus methyl ligands favors a conformation of the imine in which the bulky groups are placed away from the platinum center.21 When compound 5 was left in dichloromethane or in deuterated chloroform solution for a few hours, a new compound, 6, was formed, and after 24 h the ratio of compound 5 to compound 6 was 1:2. The complexity of the spectral pattern associated with the new compound is consistent with a monocyclometalated compound, [PtCl{(9-C14H9)CHd NCH2CH2NdCH(9-C14H8)}], 6. This is supported by the coupling of one of the imine resonances (J(H-Pt) = 112.8 Hz) and one aromatic proton (J(H-Pt) = 51.6 Hz) to 195Pt, the latter assigned to the proton adjacent to the metalation position. Recrystallization of compound 5 in dichloromethane(21) (a) Crespo, M.; Font-Bardia, M.; Solans, X. J. Organomet. Chem. 2006, 690, 1897. (b) Crespo, M.; Anderson, C. M.; Tanski, J. M. Can. J. Chem. 2009, 87, 80.

methanol produced small yellow plates of this compound along with larger orange plates corresponding to compound 6, which allowed crystallographic characterization of both compounds (see below). (22) (a) Ranatunge-Bandarage, P. R. R.; Robinson, B. H.; Simpson, J. Organometallics 1994, 13, 500. (b) Ranatunge-Bandarage, P. R. R.; Duffy, N. W.; Johnston, S. M.; Robinson, B. H.; Simpson, J. Organometallics 1994, 13, 511. (c) Ryabov, A. D.; Kazankov, G. M.; Panyashkina, I. M.; Grozovsky, O. V.; Dyachenko, O. G.; Polyakov, V. A.; Kuzmina, L. M. J. Chem. Soc., Dalton Trans. 1997, 4385. (d) Ryabov, A. D.; Panyashkina, I. M.; Polyakov, A. V.; Howard, J. A. K.; Kuz'mina, L. G.; Datt, M. S.; Sacht, C. Organometallics 1998, 17, 3615. (e) Alexandrova, L.; D'yachenko, O. G.; Kazankov, G. M.; Polyakov, V. A.; Samuleev, P. V.; Sansores, E.; Ryabov, A. D. J. Am. Chem. Soc. 2000, 122, 5189. (f) Riera, X.; Caubet, A.; Lopez, C.; Moreno, V.; Solans, X.; Font-Bardia, M. Organometallics 2000, 19, 1384. (g) Riera, X.; Lopez, C.; Caubet, A.; Moreno, V.; Solans, X.; Font-Bardia, M. Eur. J. Inorg. Chem. 2001, 2135. (h) Ryabov, A. D.; Otto, S.; Samuleev, P. V.; Polyakov, V. A.; Alexandrova, L.; Kazankov, G. M.; Shova, S.; Revenco, M.; Lipkowski, J.; Johansson, M. H. Inorg. Chem. 2002, 41 (16), 4286. (i) Ryabov, A. D.; Panyashkina, I. M.; Polyakov, V. A.; Fischer, A. Organometallics 2002, 21, 1633. (j) Perez, S.; Lopez, C.; Caubet, A.; Solans, X.; Font-Bardia, M. New J. Chem. 2003, 27, 975.

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Attempts to achieve complete transformation of compound 5 into compound 6 were carried out under more severe conditions following the procedures reported for cycloplatination processes through an electrophilic mechanism in which HCl is released.20,22 After reacting compound 5 with sodium acetate in a 1:2 ratio in toluene-methanol for 7 days, the main component of the reaction mixture was impure compound 6 and a small amount ( 2σI) R1, wR2 (all data) goodness of fit on F2 largest diff peak/hole (e/A˚3)

6

5

C35H33IN2Pt 803.62 orange, plate 0.19  0.17  0.08 125(2) monoclinic P21/n

C32H23ClN2Pt 3 1/2 CH3OH 682.09 orange, plate 0.34  0.19  0.04 125(2) monoclinic P21/c

C32H24Cl2N2Pt 702.52 yellow, plate 0.19  0.15  0.01 125(2) monoclinic C2/c

12.9448(6) 14.1221(6) 16.17207) 90 92.332(1) 90 2953.9(2), 4 1.807 5.822 1.92-29.13 100 40 076/7956 (0.0370) 7956/0/355 0.0345, 0.0887 0.0478, 0.0960 1.042 2.918, -1.877

16.102(2) 12.964(2) 12.498(2) 90 108.252(2) 90 2477.7(6), 4 1.829 5.799 2.06-28.70 100 32 689/6398 (0.0489) 6398/0/334 0.0239, 0.0540 0.0323, 0.0574 1.035 1.184, -0.783

38.073(6) 8.203(1) 28.564(5) 90 120.956(2) 90 7650(2), 12 1.830 5.738 1.25-28.31 99.7 48 948/9468 (0.0863) 9468/0/501 0.0398, 0.0693 0.0723, 0.0785 1.006 1.384, -0.944

resulting pale yellow solid was dried in vacuo. Yield: 20 mg (82%). [PtMe3I{(9-C14H9)NCH2CH2N(9-C14H9)}] (2-E,E). 1H NMR (400 MHz, CDCl3): δ -0.17 [s, 6H, 2J(Pt-H) = 75.6, Meb], 0.53 [s, 3H, 2J(Pt-H) = 72.8, Mea], 4.47 [m, 2H, CH2], 5.29 [m, 2H, CH2], 7.49 [t, 2H, J(H-H) = 7.0], 7.51 [t, 4H, J(H-H)=7.0], 7.65 [t, 2H, J(H-H)=7.2], 7.87 [d, 2H, J(H-H) =8.0], 7.98 [d, 2H, J(H-H)=8.0], 8.02 [d, 2H, J(H-H)=8.0], 8.36 [d, 2H, J(H-H)=8.0], 8.51 [s, 2H], 9.83 [s, 2H, 3J(Pt-H)= 31.2, CHdN]. MS-ESI (þ): 676 [M -I]þ. Anal. Found: C, 52.8; H, 3.8; N, 3.5. Calcd for C35H33IN2Pt: C, 52.31; H, 4.14; N, 3.48. Isomers 2-E,Z and 2-Z,Z were formed when a solution of 2-E, E was kept in CDCl3 for 24 h. 1H NMR (400 MHz, CDCl3) for 2-E,Z: δ -0.01 [s, 3H, 2J(Pt-H) = 71.5, Mec], 0.82 [s, 3H, 2 J(Pt-H)=72.5, Mea], 1.41 [s, 3H, 2J(Pt-H)=72.5, Meb], 3.73 [t, 1H, J(H-H)=12, Hd], 4.01 [tt, 2H, J(H-H)=12; 4, He], 4.98 [t, 1H, J(H-H)=12, Hd], 9.69 [s, 1H, 3J(Pt-H)=33.0, Hf], 9.72 [s, 1H, 3J(Pt-H) = 18.5, Hg]. 1H NMR (400 MHz, CDCl3) for 2-Z,Z: δ 1.36 [s, 3H, 2J(Pt-H) = 72.5, Mea], 1.63 [s, 6H, 2 J(Pt-H) = 69.0, Meb], 3.31 [m, 2H, CH2], 3.79 [m, 2H, CH2], 9.72 [s, 2H, 3J(Pt-H) = 18.5, CHdN]. Compound [PtMe{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}] (3) was obtained by refluxing for 1 h a solution of 25 mg (0.04 mmol) of compound 1 in toluene. The resulting red solution was concentrated to dryness, and the residue was washed with diethyl ether to produce a red solid. Yield: 18 mg (74%). 1H [s, J(H-Pt)=79.0, 3H, Me], NMR (500 MHz, CDCl3): δ -0.24 0 4.51 [t, J(H-H)=6.0, 2H, Hb ], 4.60 [t, J(H-H)=5.7, 2H, Hb], {7.49 [td, J(H-H) = 7.2; 1.5, 2H], 7.55 [td, J(H-H) = 6.5; 1.5, 2H], 8.07 [d, J(H-H) = 8.5, 2H], 8.33 [d, J(H-H) = 8.5, 2H], 8.63 [s, 1H] non cyclometalated anthryl}, {7.10 [t, J(H-H) = 7.5, 1H], 7.42 [t, J(H-H) = 7.5, 1H], 7.53 [m, 1H], 7.60 [dd, J(H-H) = 8.5; 1.0, 1H], 7.63 [t, J(H-H) = 7.5, 1H], 8.01 [d, J(H-H) = 8.0, 1H], 8.49 [d, J(H-H) = 8.5, 1H], 8.61 [s, 1H], 0 cyclometalated anthryl}, 10.10 [s, 3J(H-Pt) = 49.0, 1H, Ha ], 3 a 13 1 13 10.21 [s, 1H, J(Pt-H)=34.5, H ]. C NMR ( H- C0 gHSQC, 500 MHz, CDCl3): δ -8.0 [Me], 64.0 [Cb]; 68.0 Cb ], {122.0, 124.0, 125.6, 126.4, 127.0, 129.8, 130.2, 140.2, cyclometalated anthryl}; {124.6, 126.0, 126.4, 128.8, 137.4, noncyclometalated anthryl}; 150.0 [Ca], 166.0 [Ca]. MS-ESI: 645.17 [M]þ, 630.17 [M - Me]þ. Compound [Pt{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}] (4) was obtained as a dark red solid after mixing 20 mg (0.030 mmol) of compound 1, dissolved in a 1:1 mixture of

CH2Cl2-CH3OH (10 mL), with 2.1 μL (0.030 mmol) of CH3COCl for 10 min. The solvent was evaporated and the residue washed with diethyl ether. Yield: 15 mg (79%). [Pt{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}] (4). 1H NMR (400 MHz, CDCl3): δ 4.56 [s, 4H, CH2], 6.99 [dd, 2H, J(H-H) = 7.2; 1.6; 3 J(H-Pt) = 67.6, H1], 7.55 [t, 4H, J(H-H) = 7.4, H2þH6], 7.70 [t, 2H, J(H-H)=7.4, H7], 7.89 [d, 2H, J(H-H)=7.6, H3], 8.15 [d, 2H, J(H-H)=8.4, H5], 8.58 [d, 2H, J(H-H)=9.2, H8], 8.82 [s, 2H, H4], 10.06 [s, 2H, 3J(Pt-H) = 36.0, CHdN]. 13C NMR (1H-13C gHSQC, 500 MHz, CDCl3): δ 64.0 [CH2]; {122.0 [C8], 123.5 [C2 or C6], 125.0 [C3], 126.0 [C2 or C6], 127.0 [C7], 130.0 [C5], 136.0 [C4], 149.0 [C1], aromatic carbon}; 153.5 [CHdN]. MS-ESI: 671.2 [M þ MeCN]þ, 630.1 [M þ H]þ. Anal. Found: C, 58.9; H, 3.4; N, 4.3. Calcd for C32H22N2Pt 3 H2O: C, 59.35; H, 3.73; N, 4.32. Compound [PtCl2{(9-C14H9)CHdNCH2CH2NdCH(9-C14H9)}] (5) was obtained from 100 mg (0.24 mmol) of compound cis-[PtCl2(dmso)2] and 104 mg (0.24 mmol) of ligand L, which were allow to react in refluxing methanol for 4 h. The obtained orange-red solid was filtered. Yield: 150 mg (90.1%). [PtCl2{(9C14H9)NCH2CH2N(9-C14H9)}] (5). 1H NMR (400 MHz, CDCl3): δ 3.24 [s, 4H, CH2], 7.52 [t, 4H, J(H-H) = 8.0], 7.62 [t, 4H, J(H-H)=7.2], 7.86 [d, 4H, J(H-H)=8.4], 8.04 [d, 4H, J(H-H)= 8.4], 8.56 [s, 2H], 10.70 [s, 2H, CHdN]. 13C NMR (1H-13C gHSQC, 500 MHz, CDCl3): δ 58.0 [CH2]; {126.0, 128.0, 124.0, 129.5, 130.0, aromatic carbon}; 170.0 [CHdN]. MS-ESI: 720.13 [M þ NH4]þ, 1422.22 [2M þ NH4]þ. Anal. Found: C, 54.1; H, 3.5; N, 4.1. Calcd for C32H24Cl2N2Pt: C, 54.71; H, 3.44; N, 3.99. Compound [PtCl{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}] (6) was obtained as a dark red solid from 80 mg (0.11 mol) of compound 5 and 16 mg (0.22 mol) of sodium acetate in toluene (20 mL)-methanol (5 mL). The mixture was heated at 90 °C for 7 days. The red solution was concentrated to dryness, and the residue was extracted with dichloromethane. The dichloromethane was removed, and the residue was washed with diethyl ether. Yield: 35 mg (46%). 10 H NMR (400 MHz, CDCl3): δ 3.58 [t, J(H-H) = 6.0, 2H, Hb,b ], 4.27 [t, J(H-H) = 6.0, 2H, 0 Hb,b ], 7.98 [d, J(H-H) = 8.0, 2H], 8.12 [d, J(H-H) = 7.6, 2H], 8.38 [d, 1H, J(H-H) = 8.5], 8.63 [s, 1H], 8.78 [s, 1H], 9.04 [d, J(H-H)=7.0, 3J(H-Pt)=51.6, 1H], 9.84 [s, 3J(H-Pt)=112.8, 1H, Ha], 10.68 [s, 1H, Ha]. MS-ESI: 671.18 [M-Cl þ CH3CN]þ. 3.3. Reactivity Studies. 3.3.1. An excess of CD3I (0.05 mL) was added at -40 °C to an NMR tube containing a solution of

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1 (5 mg) in CDCl3. 1H NMR (500 MHz) spectra were recorded at -40, -20, 0, 10, and 20 °C as the solution was warmed. 3.3.2. A 2 μL (0.026 mmol) portion of CF3CO2H was added to a yellow solution of 20 mg (0.030 mmol) of compound 1 in CH3CN at -20 °C. The solution, which immediately turned red, was filtered, and the solvent was removed. An NMR spectrum of the residue was registered; in addition to resonances corresponding to L and 1, a minor compound was detected: δ 0.49 [s, 3H, 2J(Pt-H) = 82.4, Me], 0.84 [s, 3H, 2J(Pt-H) = 85.2, Me], 3.70 [br], 4.20 [br], 9.90 [s, 1H]. 3.4. Crystallographic Data Collection and Refinement. X-ray diffraction data were collected on a Bruker APEX 2 CCD platform diffractometer (Mo KR (λ = 0.71073 A˚)) at 125 K. Suitable crystals of 2, 5, and 6 were grown by slow diffusion of a CH2Cl2 solution into MeOH. Crystals were mounted in a nylon loop with Paratone-N cryoprotectant oil. The structures were solved using direct methods and standard difference map techniques and were refined by full-matrix least-squares procedures on F2 with SHELXTL (Version 6.14).31 All non-hydrogen atoms were refined anisotropically, with the exception of dis(31) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.

Anderson et al. ordered methanol solvate in 6. Hydrogen atoms on carbon were included in calculated positions and were refined using a riding model. In the structure of 2 there is a small substitutional disorder of the iodide and the methyl group trans to it, as indicated by the Hirshfeld test reported by CheckCIF/PLATON.32

Acknowledgment. We sincerely thank The Ministerio de Educaci on y Ciencia (project CTQ 2009-11501 M.C.), The National Science Foundation (NSF 0521237 J.T. (PI) and C.A.), Vassar College (J.T.), and Bard College (C.A.) for generous financial support. Supporting Information Available: X-ray crystallographic data in CIF format for the structure determinations of 2, 5, and 6. Molecular structure and selected bond lengths and angles for compound 5 (molecule #2). Synthesis of compound [PtMeI{(9-C14H9)CHdNCH2CH2NdCH(9-C14H8)}], 7. Bond lengths and angles for compounds 2, 5, and 6. This material is available free of charge via the Internet at http://pubs.acs.org. (32) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.