Palladium and Molybdenum Complexes of the Heteroleptic

4778

Organometallics 2009, 28, 4778–4782 DOI: 10.1021/om900166d

Palladium and Molybdenum Complexes of the Heteroleptic Organostannylene [2,6-(Me2NCH2)2C6H3]SnCl Jana Martincov
a,† Roman Jambor,*,† Markus Sch€ urmann,‡ Klaus Jurkschat,*,‡ § Jan Honzı´ cek, and Filipe A. Almeida Paz^  legiı´ 565, CZ-532 10, Department of General and Inorganic Chemistry, University of Pardubice, n
am. Cs. Pardubice, Czech Republic, ‡Lehrstuhl f€ ur Anorganische Chemie II der Technischen Universit€ at, D-44227 Dortmund, Germany, §Instituto de Tecnologia Quı´mica e Biol
ogica da Universidade Nova de Lisboa, Avenida da Rep
ublica, EAN, 2780-157, Oeiras, Portugal, and ^Department of Chemistry, University of Aveiro, CICECO, 3810-193 Aveiro, Portugal

†

Received March 2, 2009

The synthesis and molecular structures are reported for the transition metal heteroleptic organostannylene complexes {[2,6-(Me2NCH2)2C6H3]SnCl}(C5H5)(CO)2MoCl (6) and {[2,6-(Me2NCH2)2C6H3]Sn(OAc)}Pd(Cl)[2-(Me2NCH2)C6H4] (7). It is shown that the intramolecularly coordinated heteroleptic organostannylene [2,6-(Me2NCH2)2C6H3]SnCl undergoes a redox-type reaction with Pd(PPh3)4 to give cis-[2,6-(Me2NCH2)2C6H3]SnCl}2PdCl2.

Introduction The chemistry of transition metal (TM) complexes containing stannylene ligands has been an active research area during the last two decades since they appear to be catalytic reagents for several reactions, depending on the type of transition metal involved.1 The most common way to prepare such complexes is by reacting a TM-Cl complex with a stannylene SnR2 (where R is an organic or inorganic substituent). In such reactions the stannylenes may behave as a two-electron ligand,2 may insert into the TM-Cl bond,3 or may act as a reducing agent.4 Although examples for when the Sn(II) atom behaves as a two-electron σ donor (e.g., as a tertiary phosphine analogue) are known, only complexes of homoleptic stannylenes of the type R2Sn or tin(II) amides Sn(NR2)2 with sterically demanding R groups were reported *Corresponding authors. (R.J.) Fax: þ 420 466037068. E-mail: [email protected]. (K.J.) Fax: þ49 231 755 504. E-mail: klaus. [email protected]. (1) (a) Botteghi, C.; Paganelli, S.; Schionato, A.; Marchetti, M. Chirality 1991, 3, 355. (b) Gladiali, S.; Bay
on, J. C.; Claver, C. Tetrahedron: Asymmetry 1995, 6, 1453. (c) Agbossou, F.; Carpentier, J.-F.; Mortreux, A. Chem. Rev. 1995, 95, 2485. (d) Parinello, G.; Stille, J. K. J. Am. Chem. Soc. 1987, 109, 7122. (e) Koll
ar, L.; Consiglio, G.; Pino, P. J. Organomet. Chem. 1987, 330, 305. (f ) Koll
ar, L.; Bakos, J.; T
oth, I.; Heil, B. J. Organomet. Chem. 1989, 370, 257. (g) Consiglio, G.; Nefkens, S. C. A.; Borer, A. Organometallics 1991, 10, 2046. (h) Sturm, T.; Weissensteiner, W.; Mereiter, K.; K
egl, T.; Jeges, G.; Petcz, G.; Koll
ar, L. J. Organomet. Chem. 2000, 595, 93. (i) Farkar, E.; Koll
ar, L.; Moret, M.; Sironi, A. Organometallics 1996, 15, 1345. ( j) K
egl, T.; Koll
ar, L.; Szalontai, G.; Kuzmann, E.; V
ertes, A. J. Organomet. Chem. 1996, 507, 75. (k) Jedlicka, B.; Weissensteiner, W.; K
egl, T.; Koll
ar, L. J. Organomet. Chem. 1998, 563, 37. (2) (a) Lappert, M. F.; Power, P. P. J. Chem. Soc., Dalton Trans. 1985, 51. (b) Campbell, G. K.; Hitchcock, P. B.; Lappert, M. F. J. Organomet. Chem. 1985, 289, C1. (c) Schager, F.; Seevogel, K.; P€orschke, K. R.; Kessler, M.; Kr€ uger, C. J. Am. Chem. Soc. 1996, 118, 13075. (d) Knorr, M.; Hallauer, E.; Huch, V.; Veith, M.; Braunstein, P. Organometallics 1996, 15, 3868. (3) (a) Hawkins, S. M.; Hitchcock, P. B.; Lappert, M. F. J. Chem. Soc., Chem. Commun. 1985, 1592. (b) Grassi, M.; Meille, S. V.; Musco, A.; Pontellini, R.; Sironi, A. J. Chem. Soc., Dalton Trans. 1990, 251. (4) Al-Allaf, T. A. K.; Eaborn, C.; Hitchcock, P. B.; Lappert, M. F.; Pidcock, A. J. Chem. Soc., Chem. Commun. 1985, 548. pubs.acs.org/Organometallics

Published on Web 07/24/2009

prior to 2008.2,5 The latest studies showed that anionic main group element donors such as (SnB11H11)- or [MeSi{SiMe2N(aryl)}3Sn]- are also able to form stable TM-Sn(II) complexes.6 An alternative to the sterically demanding bulky substituents used in the kinetic stabilization of organostannylenes is the use of so-called built-in ligands that contain side chain substituents bearing nitrogen7 or oxygen8 donor atoms. In (5) (a) Hitchcock, P. B.; Lappert, M. F.; Misra, C. M. J. Chem. Soc., Chem. Commun. 1985, 863. (b) Krause, J.; Pluta, C.; P€orschke, K. R.; Goddard, R. J. Chem. Soc., Chem. Commun. 1993, 1254. (c) Veith, M.; Stahl, L.; Huch, V. Inorg. Chem. 1989, 28, 3278. (d) Veith, M.; Stahl, L.; Huch, V. J. Chem. Soc., Chem. Commun. 1990, 359. (e) Veith, M.; M€uller, A.; Stahl, L.; N€otzel, M.; Jarczyk, M.; Huch, V. Inorg. Chem. 1996, 35, 3848. (f ) Krause, J.; Haack, K. J.; P€orschke, K. R.; Gabor, B.; Goddard, R.; Pluta, C.; Seevogel, K. J. Am. Chem. Soc. 1996, 118, 804. (f) Zabula, A. V.; Pape, T.; Hepp, A.; Hahn, F. E. Dalton Trans. 2008, 43, 5886. (g) Zabula, A. V.; Pape, T.; Hepp, A.; Hahn, F. E. Organometallics 2008, 27, 2756. (6) Kilian, M.; Wadepohl, H.; Gade, L. H. Eur. J. Inorg. Chem. 2008, 1892. (b) Kilian, M.; Wadepohl, H.; Gade, L. H. Organometallics 2008, 27, 524. (c) Kilian, M.; Wadepohl, H.; Gade, L. H. Dalton Trans. 2008, 5, 582. (d) Kilian, M.; Wadepohl, H.; Gade, L. H. Organometallics 2007, 26, 3076. (e) Kirchmann, M.; Fleischhauer, S.; Wesemann, L. Organometallics 2008, 27, 2803. (f ) Kirchmann, M.; Gadt, T.; Eichele, K.; Wesemann, L. Eur. J. Inorg. Chem. 2008, 14, 2261. (g) Kirchmann, M.; Eichele, K.; Schappacher, F. M.; Pottgen, R.; Wesemann, L. Angew. Chem., Int. Ed. 2008, 47, 963. (h) Hagen, S.; Schubert, H.; Maichle-Mossmer, C.; Pantenburg, I.; Weigend, F.; Wesemann, L. Inorg. Chem. 2007, 46, 6775. (i) Gadt, T.; Eichele, K.; Wesemann, L. Organometallics 2006, 25, 3904. (7) (a) Angermund, K.; Jonas, K.; Kruger, C.; Latten, J. L.; Tsay, Y. H. J. Organomet. Chem. 1988, 353, 17. (b) Jastrzebski, J. T. B. H.; van der Schaaf, P. A.; Boersma, J.; van Koten, G.; de Wit, M.; Wang, Y.; Heijdenrijk, D.; Stam, C. H. J. Organomet. Chem. 1991, 407, 301. (c) Jastrzebski, J. T. B. H.; van der Schaaf, P. A.; Boersma, J.; van Koten, G.; Zoutberg, M. C.; Heijdenrijk, D. Organometallics 1989, 8, 1373. (d) Drost, C.; Hitchcock, P. B.; Lappert, M. F. Organometallics 1998, 17, 3838. (e) Drost, C.; Hitchcock, P. B.; Lappert, M. F. Angew. Chem., Int. Ed. 1999, 38, 1113. (f ) Drost, C.; Hitchcock, P. B.; Lappert, M. F.; Pierssens, L. J.-M. Chem. Commun. 1997, 1141. (8) (a) Henn, M.; Sch€ urmann, M.; Mahieu, B.; Zanello, P.; Cinquantini, A.; Jurkschat, K. J. Organomet. Chem. 2006, 691, 1560. (b) Driess, M.; Dona, N.; Merz, K. Chem.;Eur. J. 2004, 10, 5971. (c) Mehring, M.; L€ow, C.; Sch€urmann, M.; Uhlig, F.; Jurkschat, K.; Mahieu, B. Organometallics 2000, 19, 4613. r 2009 American Chemical Society

Article

Organometallics, Vol. 28, No. 16, 2009

4779

Chart 1

such functionally substituted organostannylenes the Lewis base character of the Sn(II) atom is increased as a result of the intramolecular donorfSn coordination. Subsequently, this should increase its ability to form complexes with transition metal species that are Lewis acids. Heteroleptic organostannylenes of the general formula (Y,C,Y)SnCl, where Y,C,Y refers to a pincer-type ligand, are potential candidates in this field. Despite the fact that the organostannylene [2,6-(Me2NCH2)2C6H3]SnCl (1) has been known for a long time, investigation of its reactivity is scarce and limited to oxidative additions.7b,7c Recently we reported reactions of compound 1 and the related heteroleptic organostannylene {4-tBu-2,6-[P(O)(O-iPr)2]2C6H2}SnCl (2) with selected Pd(II) complexes to give new complexes (3-5) where the heteroleptic organostannylenes 1 and 2 behave as two-electron ligands (Chart 1).9 Extending the reactivity studies toward other transition metal complexes, we report here the reactions of 1 with Pd(PPh3)4 and [Mo(CO)2(CH3CN)2Cp]þBF4 to give cis-[2,6-(Me2NCH2)2C6H3]SnCl}2PdCl2 and {[2,6-(Me2NCH2)2C6H3]SnCl}(C5H5)(CO)2MoCl, respectively. Also reported is the preparation of {[2,6-(Me2NCH2)2C6H3]Sn(OAc)}Pd(Cl)[2-(Me2NCH2)C6H4]. All compounds were characterized by 1H, 13C, and 119Sn NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis.

Results and Discussion The reaction of compound 1 with tetrakis(triphenylphosphine)palladium, Pd(PPh3)4, gave, regardless of the stoichiometry (1:1 to 1:6), a yellow solid precipitate, which was identified as cis-[2,6-(Me2NCH2)2C6H3]SnCl}2PdCl2 (3)9 (Scheme 1). (9) (a) Martincov
a, J.; Dost
al, L.; Ruzicka, A.; Taraba, J.; Jambor, R. Organometallics 2007, 26, 4102. (b) Deaky, V.; Henn, M.; Sch€urmann, M.; Jurkschat, K. 13th Vortragstagung der W€ohler-Vereinigung der GDCh, September 18-19, 2006, RWTH Aachen, Germany, Book of Abstracts, p 078. (10) (a) Ferguson, G.; McCrindle, R.; McAlles, A. J.; Parvez, M. Acta Crytallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1982, 38, 2679. (b) Kitano, Y.; Kinoshita, Y.; Nakanuta, R.; Ashida, T. Acta Crytallogr., Sect. C: Cryst. Struct. Commun. 1983, 39, 1015. (11) (a) Jambor, R.; Kasn
a, B.; Kirschner, K. N.; Sch€ urmann, M.; Jurkschat, K. Angew. Chem., Int. Ed. 2008, 47, 1650. (b) Pereira, C. C. L.; Braga, S. S.; Almeida Paz, F. A.; Pillinger, M.; Klinowski, J.; Goncalves, I. S. Eur. J. Inorg. Chem. 2006, 4278.

Scheme 1

The reaction shown in Scheme 1 appears to be a redox-type reaction. In addition to the oxidation product 3 there must be a reduction product, which is very likely the heavy acetylene analogue RSnSnR (R=2,6-(Me2NCH2)2C6H311a). Unfortunately, due to its instability,11a we were unable to isolate this product from the corresponding reaction mixture. The reaction of organostannylene 1 with bis-acetonitrile dicarbonyl cyclopendadienyl molybdenium tetrafluorobo11b provided 2,6-(Me2rate, [Mo(CO)2Cp(CH3CN)2]þBF4, NCH2)2C6H3(Cl)SnMo(CO)2CpCl (6) as crystalline material and some rather poorly soluble amorphous white precipitate (Scheme 2). Compound 6 is the result of the simultaneous replacement of acetonitrile, CH3CN, by the organostannylene 1 and chloride ion transfer from another molar equivalent of 1. Consequently the organostannylenium salt [2,6-(Me2NCH2)2C6H3]SnþBF4 must also have formed in this reaction, but so far we were unable to unambiguously identify it. Some support for its existence stems from elemental analysis (see Experimental Section), 1H NMR spectroscopy, and an electrospray ionization mass spectrum of the white precipitate. The latter shows, in the positive mode, a mass cluster centered at m/z 193 ([1,5-(Me2NCH2)2C6H4 H]þ) and, in the negative mode, the presence of tetrafluoroborate 1 anion, BF4 (m/z = 87), whereas the H NMR (CD3CN) spectrum of a solution of the white precipitate from which insoluble material had been filtered displayed resonances at δ 7.56, 7.97 (aromatic protons), 4.27 (NCH2), and 2.75 (NCH3). These signals correspond to 1,5-(Me2NCH2)2C6H4, as evidenced by addition of an authentic sample. Apparently, under the experimental conditions employed, [2,6-(Me2NCH2)2C6H3]SnþBF4 is not stable and easily hydrolyzes.

4780

Organometallics, Vol. 28, No. 16, 2009

Martincov a et al. Scheme 2

The molecular structure of the molybdenum complex 6 is shown in Figure 1, and selected bond distances and bond angles are listed in the caption. The unit cell contains two independent molecules that are linked in a head-to-tail fashion by intermolecular Cl(1) 3 3 3 H(23) and Cl(3) 3 3 3 H(3) interactions with distances of 2.769(2) and 2.762(2) A˚, respectively (see Supporting Information, Figure S1). The geometric parameters of the two molecules are rather similar, and consequently only the parameters of one molecule are given in Figure 1. The structure is based on the “four-legged piano stool motif”, which is typical for compounds of the CpMoL4 type.12 The Mo(1)-Cl(1) distance of 2.521(2) A˚ is shorter in comparison to the corresponding distance reported for other “four-legged piano stool”-type MoII complexes (e.g., 2.526(2) A˚ in CpMoCl(triphos),13a 2.541(5) A˚ in CpMoCl(CO)(dppe),13b and 2.542 (9) A˚ in CpMoCl(CO)313c). The two Mo-C(O) bond lengths of 1.955(9) and 1.973(8) A˚ are comparable to those found in CpMoI(CO)2(PBu3) (1.94(6) A˚) and CpMo(COCH3)(CO)2(PPh3) (1.951(13) A˚),14 but shorter than the average distance in other compounds with weaker donating ancillary ligands (e.g., 2.003(34) A˚ in (C5H4Me)MoI(CO)2[P(OMe)3] and 2.091(14) A˚ in CpMoBr(CO)2(PPh3)).15 The Sn(1)-Mo(1) bond distance is 2.7195(9) A˚, which is shorter than the Mo(II)-Sn(II) distance in (Cp)(CO)3MoSnC6H3-2,6-Mes2 (2.9045(10) A˚)16 and the Mo(0)-Sn(II) distance in [(OC)5ModSnRR0 ] (R = 2,4,6-tBu3C6H2, R0 = CH2C(CH3)2-3,5-tBu2C6H2, 2.756(1) A˚17). This hints at the strong donor capacity of organostannylene 1. The Sn(1) atom is fivecoordinate and exhibits a distorted square-pyramidal configuration with the N(1), N(2), C(8), and Mo(1) atoms located in the equatorial positions and the Cl(2) atom in the axial position, respectively. The intramolecular Sn(1)N(1), Sn(1)-N(2), Sn(1)-Cl(2), and Sn(1)-C(8) distances are 2.494(6), 2.567(7), 2.452(2), and 2.120(10) A˚, respectively. These distances are similar to the corresponding ones reported for the parent organostannylene 1 (2.525(8), 2.602(8), 2.488(3), and 2.158(8) A˚).7c Notably, the Cl(1) atom approaches the Sn(1) atom opposite the Cl(2) atom at a distance of 2.972(2) A˚, which is shorter than the sum of the van der Waals radii of tin (2.20 A˚) and chlorine (1.70-1.90 A˚). (12) Abugideiri, F.; Fettinger, J. C.; Keogh, D. W.; Poli, R. Organometallics 1996, 15, 4407. (13) (a) Cole, A. A.; Mattamana, S. P.; Poli, R. Polyhedron 1996, 15, 2351. (b) Bush, M. A.; Hardy, A. D. U.; Manojlovic-Muir, L.; Sim, G. A. J. Chem. Soc. A 1971, 1003–1009. (c) Chaiwaise, S.; Fenn, R. H. Acta Crystallogr., Sect. B 1968, B24, 525. (14) (a) Fenn, R. H.; Cross, J. H. J. Chem. Soc. A 1971, 3312. (b) Churchill, M. R.; Fennessey, J. P. Inorg. Chem. 1968, 7, 953. (15) (a) Hardy, A. D. U.; Sim, G. A. J. Chem. Soc., Dalton Trans. 1972, 1900. (b) Sim, G. A.; Sime, J. G.; Woodhouse, D. I.; Knox, G. R. Acta Crystallogr., Sect. B 1979, B35, 2403. (16) Eichler, B. E.; Phillips, A. D.; Haubrich, S. T.; Mork, B. V.; Power, P. P. Organometallics 2002, 21, 5622. (17) Weidenbruch, M.; Stilter, A.; Peters, K.; von Schnering, H. G. Z. Anorg. Allg. Chem. 1996, 622, 534.

The 1H NMR spectrum of compound 6 showed, in addition to a singlet at δ 5.51 (Cp protons) and signals at δ 7.05 and 7.26 (aromatic protons), an AB-type resonance at δ 3.79 for the NCH2 and a singlet resonance at δ 2.54 for the NCH3 protons. This indicates that a dynamic process takes place, but this was not investigated further. The 119Sn NMR spectrum displayed a signal at δ 105, which is low-frequency shifted with respect to the noncoordinated organostannylene ligand (δ 157).7c The 13C NMR spectrum (δ(13C(CO)) at 266.7) together with IR spectroscopy ((CO) at 1946 and 1860 cm-1) proved the presence of CO groups in 6. The compounds shown in Chart 1, as well as compound 6, contain both Sn-Cl and TM-Cl bonds, which invokes the question concerning the reactivity of these functionalities toward nucleophiles. However, attempts at isolating pure products from the reaction of the organostannylene palladium complex 3 with silver acetate, AgOAc, were unsuccessful. In contrast, the reaction of the organostannylene complex [2,6-(Me2NCH2)2C6H3SnCl][2-(Me2NCH2)C6H4]PdCl (4), which contains both a N,C,N- and a C,N-coordinating ligand, with AgOAc gave, under exclusive Sn-Cl substitution, the monoacetate-substituted complex [2,6-(Me2NCH2)2C6H3SnOAc][2-(Me2NCH2)C6H4]PdCl (7) (eq 1).

The molecular structure of compound 7 is shown in Figure 2, and selected geometric parameters are given in the figure caption. The palladium and tin atoms are four- and five-coordinate, respectively, and exhibit a square-planar (Pd) and a strongly distorted trigonal-bipyramidal (Sn) configuration with the N(1), N(2) atoms occupying axial positions and the O(1), C(1), Pd(1) atoms occupying equatorial positions. The distortion from the ideal trigonal bipyramid is especially manifested by the N(1)-Sn(1)-N(2) angle of 146.61(12), which differs significantly from the ideal value of 180. The Pd(1)-N(3) distance of 2.154(4) A˚ is comparable to those found in related monomeric palladium complexes containing similar C,N-chelating ligands (range 2.140-2.155 A˚),18 but is longer than those found in the dimeric complex (18) For most recent structures see for example: (a) Qin, Y.; Lang, H.; Vittal, J. J.; Tan, G. K.; Selvaratnam, S.; White, A. J. P.; Williams, D. J.; Lejny, P. H. Organometallics 2003, 22, 3944. (b) Dunina, V. V.; Gorunova, O. N.; Grishin, Y. K.; Kuz'mina, L. G.; Churakov, A. V.; Kuchin, A. V.; Howard, J. A. K. Russ. Chem. Bull. 2005, 2010. (c) Apfelbacher, A.; Braunstein, P.; Brissieux, L.; Walter, R. Dalton Trans. 2003, 1669. (d) McCarthy, M.; Goddard, R.; Guiry, P. J. Tetrahedron: Asymmetry 1999, 10, 2797. (e) Dunina, V. V.; Kuz'mina, L. G.; Rubina, M. Y.; Grishin, Y. K.; Veits, Y. A.; Kazakova, E. I. Tetrahedron: Asymmetry 1999, 10, 1483.

Article

Organometallics, Vol. 28, No. 16, 2009

4781

Figure 1. Molecular structure of 6 together with selected bond lengths (A˚) and angles (deg). The data of only one of the two independent molecules are given. Sn(1)-Mo(1) 2.7195(9), Sn(1)-Cl(2) 2.452(2), Sn(1)-N(1) 2.494(6), Sn(1)-N(2) 2.567(7); Sn(1)-C(8) 2.120(10), Sn(1) 3 3 3 Cl(1) 2.972(2), Mo(1)-Cl(1) 2.521(2); C(8)-Sn(1)-Mo(1) 145.8(2), C(8)-Sn(1)-N(1) 71.2(3), C(8)-Sn(1)-N(2) 74.2(3), N(1)-Sn(1)-N(2) 145.2(2), N(1)-Sn(1)-Mo(1) 104.3(2), N(2)-Sn(1)-Mo(1) 106.4(2), C(8)-Sn(1)-Cl(2) 98.0(2), N(1)-Sn(1)-Cl(2) 93.3(2), Mo(1)Sn(1)-Cl(2) 116.2(5), N(2)-Sn(1)-Cl(2) 87.6(2).

({2-(Me2NCH2)C6H4}Pd-μ-Cl)2 (2.073 A˚).19 The Sn(1) atom is coordinated trans to the N(3) atom (Sn(1)-Pd(1)N(3) 174.60(13)) at a Pd(1)-Sn(1) distance of 2.4972(6) A˚, which is nearly identical to 2.4956(8) A˚ found in the chlorosubstituted analogue 4. The Sn(1)-N(1) and Sn(1)-N(2) distances are 2.441(3) and 2.533(3) A˚, respectively. The Sn(1)-O(1) (2.097(3) A˚) and Sn(1)-O(2) (3.037(3) A˚) distances are rather different and hint at a monodentate rather than a bidentate coordination mode of the acetate substituent. Notably, there are intramolecular Cl(1) 3 3 3 H(29C) and Cl(1) 3 3 3 H(7A) distances of 2.785(1) and 2.838(1) A˚, which are shorter than the sum of the van der Waals radii for chlorine (1.70-1.90 A˚) and hydrogen (1.20-1.45 A˚). In addition to the aromatic proton resonances and the singlet for the acetate protons, the 1H NMR spectrum of 7 shows three equally intense singlet resonances for the N-methyl (δ 1.97, 2.66, 2.95) protons, and a singlet (δ 4.00) and an AB-type resonance (δ 3.78) for the N-methylene protons. These resonances unambiguously indicate that compound 7 is stereochemically rigid on the 1H NMR time scale. The 119Sn NMR spectrum shows a singlet at δ -202 that is low-frequency shifted compared to the chloro-substituted complex 4. In conclusion we have shown (i) that the intramolecularly coordinated organostannylene 1 is a two-electron donor, even to transition metal moieties containing TM-Cl bonds, (ii) that the organostannylene 1 is an oxidizing reagent toward Pd(PPh3)4, and (iii) that in the organostannylene palladium complex 7 a nucleophilic attack is preferred at the Sn-Cl over the Pd-Cl functionality.

Experimental Section General Methods. The starting compounds 1 and 2 were prepared according to literature.7c,9 All reactions were carried out under argon, using standard Schlenk techniques. Solvents were dried by standard methods, distilled prior to use, and operations involving silver salts were light protected. The 1 H, 13C, 31P, and 119Sn NMR spectra were recorded at ambient temperature on Bruker Avance 500 and DPX 300 spectro(19) Mentek, A.; Kemmitt, R. D. W.; Fawcett, J.; Russell, D. R. J. Mol. Struct. 2004, 693, 241.

Figure 2. Molecular structure of 7 together with selected bond lengths (A˚) and angles (deg): Sn(1)-Pd(1) 2.4972(6), Sn(1)C(1) 2.123(4), Sn(1)-N(1) 2.441(3), Sn(1)-N(2) 2.533(3), Sn(1)O(1) 2.097(3), Pd(1)-C(21) 1.995(4), Pd(1)-Cl(1) 2.3972(12), Pd(1)-N(3) 2.157(3); C(1)-Sn(1)-Pd(1) 132.93(11), C(1)-Sn(1)-O(1) 100.52(14), O(1)-Sn(1)-Pd(1) 125.22(9), N(1)-Sn(1)-N(2) 146.61(12), Sn(1)-Pd(1)-N(3) 174.60(13), Cl(1)Pd(1)-C(21) 176.24(12). meters. The chemical shifts δ are given in ppm and referenced to external SiMe4 (1H, 13C), H3PO4 (85%, 31P), and SnMe4 (119Sn). The IR spectra were recorded on a Perkin-Elmer 684 spectrometer. Electrospray mass spectra (ESI-MS) were recorded in the positive mode on an Esquire3000 ion trap analyzer (Bruker Daltonics) and in the negative mode on the Platform quadrupole analyzer. Reaction of [2,6-(Me2NCH2)2C6H3]SnCl (1) with Pd(PPh3)4. Tetrakis(triphenylphosphine)palladium(0) (0.13 g, 0.12 mmol) was added to a magnetically stirred solution of the organostannylene 1 (0.08 g, 0.23 mmol) in THF (5 mL). Stirring was continued for 12 h, during which precipitation of a yellow solid was observed that was isolated and identified as 3. The 31P NMR spectrum of the remaining THF solution showed resonances at δ 34.2 (integral 1, trans-Pd(PPh3)2Cl2) and -4.8 (integral 15, PPh3). Synthesis of [{2,6-(Me2NCH2)2C6H3}SnCl](C5H5)Mo(CO)2Cl] (6). A slurry of [CpMo(CO)2(NCCH3)2][BF4]11b (0.10 g; 0.26 mmol) in THF (25 mL) was treated with 1 (0.20 g, 0.58 mmol). After stirring the reaction mixture for 16 h the solvent was evaporated in vacuo to give a solid residue that was washed with n-hexane (3  10 mL) and then extracted with CH2Cl2. The extract was evaporated and the crude product was recrystallized from CH2Cl2/hexane to give 126 mg (82% yield) of 6 as red crystalline material with mp 198 C (dec). Anal. Calcd for C19H25Cl2MoN2O2Sn (598.96): C, 38.10; H, 4.21. Found: C, 38.07; H, 4.19. 1H NMR (CDCl3, 500.13 MHz): δ (ppm) 2.54 (s, 12H, NCH3), 3.79 (AB system, 4H, CH2N), 5.51 (s, 5H, C5H5),

4782

Organometallics, Vol. 28, No. 16, 2009

7.05 (d, 2H, ArH), 7.26 (t, 1H, ArH). 13C NMR (CDCl3, 125.7 MHz): δ (ppm) 46.6 (NCH3), 65.8 (CH2N), 92.6 (C5H5), 125.9, 130.0, 144.2, 149.8, 266.7 (2C, CO). 119Sn NMR (CDCl3, 186.5 MHz): δ (ppm) 105.4. IR (KBr): ν(cm-1) 1946(vs) [ν(CO)], 1860(vs) [ν(CO)]. The white residue that is insoluble in CH2Cl2 was analyzed by 1 H NMR spectroscopy, elemental analysis, and ESI-MS, suggesting the formation of organostannylenium salt {[2,6-(Me2NCH2)2C6H3]Sn(CH3CN)þ}BF4 Anal. Calcd for C14H22BF4N3Sn (437.84): C, 38.41; H, 5.06. Found: C, 38.08; H, 5.39. 1H NMR (CD3CN, 500.13 MHz): δ (ppm) 2.75 (NCH3), 4.27 (NCH2), 7,56, 7.97 (C6H4). ESI-MS: negative mode m/z 87 [BF4]-; positive mode m/z 193 [C12H21N2]þ. Synthesis of {[2,6-(Me2NCH2)2C6H3](O2CCH3)Sn}[2-(Me2NCH2)C6H4]PdCl (7). Under magnetic stirring, AgOAc (52 mg, 0.31 mmol) was added to a solution of 1 (195 mg, 0.31 mmol) in THF (40 mL). After stirring for 2 h, the suspension was filtered and the solvent was evaporated to give a yellow solid residue, which was washed with hexane (2  10 mL). The residue was recrystallized from CH2Cl2/hexane to give 180 mg (90%) of 7 as yellow crystalline material with mp 141 C (dec). Anal. Calcd for C23H35ClN3O2PdSn (646.10): C, 42.46; H, 5.16. Found: C, 42.34; H, 5.03. 1H NMR (C6D6, 500.13 MHz): δ (ppm) 1.97 (s, 6H, NCH3), 2.49 (s, 3H, OAc), 2.66 (s, 6H, NCH3), 2.95 (s, 6H, NCH3) 3.78 (AB system, 4H, CH2N), 4.00 (s, 2H, CH2N) 6.79 (d, 2H, ArH), 7.00 (t, 1H, ArH) 7.27-7.55 (m, 4H, ArH). 13 C NMR (C6D6, 125.77 MHz): δ (ppm) 21.1 (OAc), 46.8 (NCH3), 49.7 (NCH3), 64.5 (CH2N), 72.5 (CH2N), 122.7, 125.1, 125.3, 129.7, 142.2, 142.5, 143.7, 144.9, 148.7, 149.7. 119 Sn NMR (C6D6, 186.49 MHz): δ (ppm) -202. Crystallography. Single crystals of 6 (red) and 7 (yellow) were obtained by slow evaporation from their respective solutions in dichloromethane/n-hexane. Crystals were mounted on a glass fiber with epoxy cement and measured on a KappaCCD diffractometer with a CCD area detector by monochromatized Mo KR radiation (λ = 0.71073 A˚) at 100(2) K. The details pertaining to the data collection and refinement for crystals are as follows. For 6: C18H24Cl2MoN2O2Sn, Mr = 1195.86, ortho(20) Sheldrick, G. M. SHELX-97 program package; University of Goettingen, 1997. (21) Sheldrick, G. M. SHELXTL V 5.10; Bruker AXS Inc.: Madison, Wl, 1997.

Martincov a et al. rhombic, space group P2c-2n, a=14.7541(5) A˚, b=9.0836(3) A˚, c = 32.1522(11) A˚, R = 90, β = 98.0965(9), γ = 90, Z = 4, F = 1.843 g 3 cm-3, μ = 2.006 mm-1, crystal size 0.38  0.25  0.15 mm, crystal shape block, θ range 2.33-29.24, Tmin, Tmax 0.5161, 0.7529, 76 740 reflections collected, of which 12 669 were independent [R(int) = 0.0763], [I > 2σ(I)]: R1=0.0549, wR2 = 0.1195. For 7: C23H34ClN3O2PdSn, M=645.07, triclinic, space group P1, a = 9.5414(13) A˚, b = 9.6605(16) A˚, c = 14.696(2) A˚, R = 93.684(6), β = 90.180(8), γ = 108.526(8), Z = 2, F(calcd) = 1.672 Mg/m-3, μ=1.804 mm-1, crystal size 0.080.080.06 mm, crystal shape block, θ range 2.92-25.35, 11 680 reflections collected, of which 4685 were independent [R(int) = 0.04], no. of observed reflections [I > 2σ(I)] 2347, no. of parameters 287, S all data 0.519, final R indices [I > 2σ(I)]: R1 = 0.0276, wR2= 0.0526. The empirical absorption corrections were applied (multiscan from symmetry-related measurements). The structures were solved by the direct method (SIR9720) and refined by a fullmatrix least-squares procedure based on F2 (SHELXL9721). Hydrogen atoms were fixed in idealized positions (riding model) and assigned temperature factors Hiso(H)=1.2Ueq(pivot atom); for the methyl moiety a multiple of 1.5 was chosen. The final difference maps displayed no peaks of chemical significance.

Acknowledgment. The authors thank the Grant Agency of the Czech Republic (project no. GA370468), the Ministry of Education of the Czech Republic (project nos. VZ0021627501 and LC523), and the Erasmus Program of the EU and Technische Universit€at Dortmund for financial support. Supporting Information Available: Further details of the structure determination of compounds 6 and 7, including atomic coordinates, anisotropic displacement parameters, and geometric data are available free of charge via the Internet at http://pubs.acs.org. Crystallographic data for compounds 6 and 7 have been deposited with the Cambridge Crystallographic Data Centre, CCDC no. 682434 and no. 713747).