SnCl as a Ligand in Transition Metal Complexes of Palladium

Organometallics 2009, 28, 4823–4828 DOI: 10.1021/om900393k

4823

The Stannylene {2,6-(Me2NCH2)2C6H3}SnCl as a Ligand in Transition Metal Complexes of Palladium, Ruthenium, and Rhodium


Jana Martincov
a, Romana Dost
alov
a, Libor Dost
al, Ales Ruzicka, and Roman Jambor*  legiı´ 565, CZ-532 10, Department of General and Inorganic Chemistry, University of Pardubice, n
am. Cs. Pardubice, Czech Republic Received May 14, 2009

The cleavage of the chloride bridge in the dimeric transition complexes [(η3-C3H5)Pd]2(μ-Cl)2, [(η6benzene)RuCl]2(μ-Cl)2, [(η6-cymene)RuCl]2(μ-Cl)2, [(CΟ)3RuCl]2(μ-Cl)2, and [(CΟ)2Rh]2(μ-Cl)2 by heteroleptic LSnCl stannylene (L is a N,C,N-pincer ligand [2,6-(Me2NCH2)2C6H3]) resulted in the isolation of PdII-SnII, RuII-SnII, and RhI-SnII complexes [Pd(η3-C3H5)(LSnCl)Cl] (2), [Ru(η6benzene)(LSnCl)Cl2] (3), [Ru(η6-cymene)(LSnCl)Cl2] (4), [Ru(CO)3(LSnCl)Cl2] (5), and [Rh(CO)2(LSnCl)Cl] (6). All compounds were characterized by NMR and IR spectroscopy, and the structures of compounds 2 and 4 were determined by X-ray diffraction analysis. The structure of a rare monomeric RhII-SnII complex, [Rh(LSnCl)2Cl2] (7), the final decomposition product of RhI-SnII complex 6, is also reported. Introduction The chemistry of transition metal (TM) complexes containing stannylene ligands has developed into an active area of research during the last two decades. Such complexes are believed to be preformed catalysts for several reactions depending on the type of transition metal.1 It was demonstrated that stannylenes behave as two-electron σ-donor *Corresponding author. Fax: þ 420 466037068. E-mail: roman. [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. (l) Zabula, A. V.; Hahn, F. E. Eur. J. Inorg. Chem. 2008, 33, 5165. (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) Hitchcock, P. B.; Lappert, M. F.; Misra, C. M. J. Chem. Soc., Chem. Commun. 1985, 863. (d) Hawkins, S. M.; Hitchcock, P. B.; Lappert, M. F. J. Chem. Soc., Chem. Commun. 1985, 1592. (e) Al-Allaf, T. A. K.; Eaborn, C.; Hitchcock, P. B.; Lappert, M. F.; Pidcock, A. J. Chem. Soc., Chem. Commun. 1985, 548. (f) Schager, F.; Seevogel, K.; P€orschke, K. R.; Kessler, M.; Kr€ uger, C. J. Am. Chem. Soc. 1996, 118, 13075. (g) Krause, J.; Pluta, C.; P€ orschke, K. R.; Goddard, R. J. Chem. Soc., Chem. Commun. 1993, 1254. (h) Krause, J.; Haack, K. J.; P€orschke, K. R.; Gabor, B.; Goddard, R.; Pluta, C.; Seevogel, K. J. Am. Chem. Soc. 1996, 118, 804. (i) Knorr, M.; Hallauer, E.; Huch, V.; Veith, M.; Braunstein, P. Organometallics 1996, 15, 3868. ( j) Grassi, M.; Meille, S. V.; Musco, A.; Pontellini, R.; Sironi, A. J. Chem. Soc., Dalton Trans. 1990, 251. (k) Veith, M.; Stahl, L.; Huch, V. Inorg. Chem. 1989, 28, 3278. (l) Veith, M.; Stahl, L.; Huch, V. J. Chem. Soc., Chem. Commun. 1990, 359. (m) Veith, M.; M€uller, A.; Stahl, L.; N€ otzel, M.; Jarczyk, M.; Huch, V. Inorg. Chem. 1996, 35, 3848. (n) Zabula, A. V.; Pape, T.; Hepp, A.; Hahn, F. E. Dalton Trans. 2008, 43, 5886. (o) Zabula, A. V.; Pape, T.; Hepp, A.; Hahn, F. E. Organometallics 2008, 27, 2756. r 2009 American Chemical Society

ligands similar to tertiary phosphines. Preliminary work describing TM-SnII complexes involved the use of homoleptic stannylenes of type R2Sn or tin(II) amides Sn(NR2)2 with sterically demanding substituents R.2 A recent study 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.3 An alternative to sterically demanding substituents for the stabilization of organostannylenes are the so-called built-in ligands that contain side chain substituents bearing nitrogen4 or oxygen5 donor atoms. In such functional substituted organostannylenes the Lewis base character of the Sn(II) atom is increased as result of the intramolecular donor-Sn coordination. This, in turn, should increase the ability to form complexes with Lewis acids such as transition metals. Previously, it was shown that the homoleptic stannylene (3) (a) 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.; P€ottgen, 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. (4) (a) Angermund, K.; Jonas, K.; Kr€ uger, 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. (5) (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. Published on Web 07/10/2009

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Organometallics, Vol. 28, No. 16, 2009

Martincov a et al.

Chart 1

(2-(Me2NCH2)C6H4)2SnII behaved similarly to SnCl2, and only the products of insertion into the TM-Cl bond were isolated.6 On the other hand, the organobismuth compound (2-(Me2NCH2)C6H4)2BiCl was used for the synthesis of the complex [Au(C6F5)2][Bi(C6H4CH2NMe2-2)2], where a Au(I) 3 3 3 Bi(III) bonding interaction was achieved.7 Recently we have reported the preparation of PdII complexes of the heteroleptic organostannylene LSnCl (1), in which 1 itself acts as a two-electron-donor ligand (Chart 1).8 The monomeric complex {Pd[2-(Me2NCH2)C6H4](LSnCl)Cl} (Chart 1B) was prepared by the cleavage of the chloride bridge in the starting dimeric complex [{2-(Me2NCH2)C6H4}Pd]2(μ-Cl)2. This reaction could be of general use for preparation of a variety TM-SnII complexes. To investigate whether 1 also can cleave the chloride bridge of other dimeric TM complexes, the reactions of 1 with [(η3-C3H5)Pd]2( μ-Cl)2, [(η6-benzene)RuCl]2( μ-Cl)2, [(η6-cymene)RuCl]2( μCl)2, [(CΟ)3RuCl]2( μ-Cl)2, and [(CΟ)2Rh]2(μ-Cl)2 were examined and found to yield the PdII-SnII, RuII-SnII, and RhI-SnII complexes [Pd(η3-C3H5)(LSnCl)Cl] (2), [Ru(η6benzene)(LSnCl)Cl2] (3), [Ru(η6-cymene)(LSnCl)Cl2] (4), [Ru(CO)3(LSnCl)Cl2] (5), and [Rh(CO)2(LSnCl)Cl] (6). All compounds were characterized by NMR and IR spectroscopy, and the structures of 2 and 4 were determined by X-ray diffraction analysis. The structure of the rare monomeric RhII-SnII complex [Rh(LSnCl)2Cl2] (7), the final decomposition product of RhI-SnII complex 6, is also reported.

Results and Discussion The synthesis of the complex [Pd(η3-C3H5)(LSnCl)Cl] (2) was carried out according to Scheme 1. The molecular structure of complex 2 is shown in Figure 1, and selected bond distances and bond angles are listed in the figure caption. The unit cell contains two independent molecules with similar geometric parameters. The parameters of one molecule are given. The palladium and tin atoms are four- and five-coordinated, respectively, and exhibit square-planar (Pd) and distorted trigonal-bipyramidal (Sn) configurations with the N1 and N2 atoms occupying the axial positions and the Cl1, C1, and Pd1 atoms occupying the equatorial positions of the latter. The Sn1 atom is coordinated trans to the C15 atom (Sn1-Pd1-C15 161.24(19)°) at a Pd1-Sn1 distance of 2.5556(5) A˚, which is longer than the distance of 2.4956(8) A˚ found for C,N-substituted PdII analogue{Pd


(6) Padelkov
a, Z.; Cı´ sarov
a, I.; Fejfarov
a, K.; Holubov
a, J.; Ruzicka, A.; Holecek, J. Collect. Czech. Comm. 2007, 72, 629. (7) Fernandez, E. J.; Laguna, A.; Polez-de-Lazura, J. M.; Monge, M.; Nema, M.; Olmos, M. E.; Perez, J.; Silvestru, C. Chem. Commun. 2007, 6, 571.
(8) Martincov
a, J.; Dost
al, L.; Ruzicka, A.; Taraba, J.; Jambor, R. Organometallics 2007, 26, 4102.

Figure 1. ORTEP view of 2. The thermal ellipsoids are drawn with 50% probability. Hydrogen atoms are omitted for clarity. Selected bond distances (A˚) and angles (deg): Sn1-C1 2.121(5), Sn1-Cl1 2.4384(14), Sn1-N1 2.456(4), Sn1-N2 2.507(4), Sn1-Pd1 2.5556(5), Pd1-C13 2.117(6), Pd1-C15 2.199(6), Pd1-Cl2 2.3424(13), C1-Sn1-Cl1 99.14(14), C1-Sn1-Pd1 148.2414, Cl1-Sn1-Pd1 112.62(4), N1-Sn1-N2 147.30(14), C13-Pd1-Cl2 163.6(2), C15-Pd1-Sn1 161.24(19), N1-Sn1Pd1 106.05(11).

Scheme 1

[2-(Me2NCH2)C6H4](LSnCl)Cl}.8 The Sn1-N1 and Sn1N2 distances are 2.456(4) and 2.507(4) A˚, respectively, being unaffected by the coordination of 1 to the PdII atom (SnN = 2.525(8) and 2.602(8) A˚ in 1).4c The structure of 2 is retained in C6D6 solution. The 1H NMR spectrum of 2 showed an AX spin system at 3.52 and 3.91 ppm for CH2N and two signals at 2.23 and 2.43 ppm for the CH3 groups of the ligand L, indicating the presence of equivalent CH2NMe2 moieties. The CH2N benzyl protons and NMe2 groups are already diastereotopic at low temperature in the starting LSnCl (1),4c and the fact that the number of signals of L is preserved at ambient temperature in 2 suggests that complex 2 does not dissociate in solution. The doublets at 1.50 and 2.20 ppm for Hanti protons and the doublets at 3.66 and 4.61 ppm for Hsyn protons prove the η3coordination mode of the allyl group in 2.9 The 13C NMR spectrum of 2 showed the signals of the allyl group at 47.3 and 78.7 ppm for Cterm and at 112.5 ppm for Cmeso. The value (9) (a) Normand, A. T.; Stasch, A.; Ooi, L. L.; Cavell, K. J. Organometallics 2008, 27, 6507. (b) Aakermark, B.; Krakenberger, B.; Hansson, S.; Vitagliano, A. Organometallics 1987, 6, 620. (c) Torralba, M. C.; Campo, J. A.; Heras, J. V.; Bruce, D. W.; Cano, M. Dalton Trans. 2006, 3918. (d) Johns, A. M.; Tye, J. W.; Hartwig, J. F. J. Am. Chem. Soc. 2006, 128, 16010. (e) Auburn, P. R.; Mackenzie, P. B.; Bosnich, B. J. Am. Chem. Soc. 1985, 107, 2033. (e) Bastero, A.; Bella, A. F.; Fern
andez, F.; Jansat, S.; Claver, C.; G
omez, M.; Muller, G.; Ruiz, A.; Font-Bardía, M.; Solans, X. Eur. J. Inorg. Chem. 2007, 1, 132. (f) Schott, D.; Pregosin, P. S.; Veiros, L. F.; Calhorda, M. J. Organometallics 2005, 24, 5710. (g) Ding, Y.; Goddard, R.; P€orschke, K. R. Organometallics 2005, 24, 439. (h) Chernyshova, E. S.; Goddard, R.; P€orschke, K. R. Organometallics 2007, 26, 3236. (i) Filipuzzi, S.; Pregosin, P. S.; Albinati, A.; Rizzato, S. Organometallics 2008, 27, 437.

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Organometallics, Vol. 28, No. 16, 2009

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Scheme 2

of δ(119Sn)=126.0 ppm is shifted upfield compared to the starting compound 1 (157 ppm). The upfield shift of δ(119Sn) was also observed in monomeric PdII complex {Pd[2-(Me2NCH2)C6H4](LSnCl)Cl} (Chart 1B),8 and thus it could be of diagnostic value in these cleavage-type reactions when new TM-SnII complexes are formed (vide infra). Compound 2 is unstable in benzene or CH2Cl2 solution and decomposes to Pd black within one week at rt. This instability can be attributed to η3-η1-η3 rearrangement of the allyl group in PdII complex 2. Upon switching from η3 to η1 coordination, the allyl group is analogous to a σ-bonded alkyl group generating an unstable PdII-alkyl-SnII species. Such decomposition is well-defined in the carbene-containing PdII π-allyl complexes PdII-alkyl-NHC (NHC=N-heterocyclic carbene), which were studied as a cross-coupling catalyst.10 The cleavage reaction of dimeric TM complexes was also applied to the synthesis of RuII-SnII complexes. The treatment of 1 with [(η6-benzene)RuCl]2(μ-Cl)2 or [(η6cymene)RuCl]2(μ-Cl)2 produced complexes [Ru(η6benzene)(LSnCl)Cl2] (3) and [Ru(η6-cymene)(LSnCl)Cl2] (4), respectively, in which the SnII atom coordinates to the RuII atom (Scheme 2). The 1H NMR spectra of 3 and 4 showed an AX spin system for CH2N and a broad signal for CH3 groups. The presence of equivalent CH2NMe2 groups indicates hindered rotation about the Sn-Ru bond in 3 and 4. The protons of the phenyl ligand in 3 appear as a singlet at 5.28 ppm, and the ring protons of the cymene ligand in 4 constitute an AB spin system (δA 5.58, δB 5.67) with JAB being approximately 7 Hz. The 13C NMR spectra showed the signals of the phenyl group at 84.1 ppm in 3 and of the cymene group at 82.2 ppm for C2,6{ring} and 83.8 ppm for C3,5{ring} in 4. The 119Sn NMR spectra of 3 and 4 showed one signal at -109.9 ppm (3) and at -128.2 ppm (4) being shifted upfield relative to 1 (157 ppm). The molecular structure of complex 4 is shown in Figure 2, and selected bond distances and bond angles are listed in the figure caption. The ruthenium and tin atoms are six- and five-coordinated, respectively, and exhibit an octahedral (Ru) and a distorted square-pyramidal (Sn) configuration, with N1, N2, C1, and Cl1 atoms being located in equatorial positions and the Ru1 atom in the axial position, with respect to the latter. The bond angles of N1-Sn1-N2 and C1-Sn1-Cl1 being (10) (a) McGuinness, D. S.; Cavell, K. J. Organometallics 2000, 19, 4918. (b) McGuinness, D. S.; Saendig, N.; Yates, B. F.; Cavell, K. J. J. Am. Chem. Soc. 2001, 123, 4029. (c) Cavell, K. J.; McGuinness, D. S. Coord. Chem. Rev. 2004, 248, 671. (d) Bacciu, D.; Cavell, K. J.; Fallis, I. A.; Ooi, L. Angew. Chem., Int. Ed. 2005, 44, 5282. (e) Graham, D. C.; Cavell, K. J.; Yates, B. F. Dalton Trans. 2005, 1093. (f ) Graham, D. C.; Cavell, K. J.; Yates, B. F. Dalton Trans. 2006, 1768. (g) Nielsen, D. J.; Cavell, K. J.; Skelton, B. W.; White, A. H. Inorg. Chim. Acta 2006, 359, 1855. (h) Magill, A. M.; Yates, B. F.; Cavell, K. J.; Skelton, B. W.; White, A. H. Dalton Trans. 2007, 3398.

Figure 2. ORTEP view of 4. The thermal ellipsoids are drawn with 50% probability. Hydrogen atoms together with the molecules of CHCl3 are omitted for clarity. Selected bond distances (A˚) and angles (deg): Sn1-C1 2.122(3), Sn1-Cl1 2.4362(8), Sn1-N1 2.492(3), Sn1-N2 2.542(3), Sn1-Ru1 2.5934(3), Ru1-Cl2 2.4227(8), Ru1-Cl3 2.4284(8), C1-Sn1N1 74.00(11), Cl1-Sn1-N1 85.10(6), C1-Sn1-N2 73.30(11), Cl1-Sn1-N2 84.74(6), C1-Sn1-Cl1 115.71(9), N1-Sn1-N2 137.06(9), N1-Sn1-Ru1 113.98(6), N2-Sn1-Ru1 108.60(6), C18-Ru1-Sn1 91.37(9), C17-Ru1-Sn1 95.17(9), Cl2-Ru1Sn1 85.25(2), Cl3-Ru1-Sn1 81.60(2).

137.06(9)° and 115.71(9)° differ from those found in the parent organostannylene 1 (143.0° and 95.0 (3)°),4c respectively, which may be attributed to the distorted squarepyramidal configuration of the Sn atom in 4. The geometry at ruthenium is essentially octahedral with cis interligand angles in the range 81.6(2)-95.17(9)°. Both chlorine atoms, mutually in cis positions (Cl2-Ru1-Cl3 = 84.64(3)°), are coordinated cis to the Sn1 atom (angles Sn1-Ru1-Cl3 = 81.60(2)° and Sn1-Ru1-Cl2 = 85.25(2)°). The value of the Ru1-Sn1 distance is 2.5934(3) A˚. Analogously, the treatment of 1 with [(CΟ)3RuCl]2(μ-Cl)2 gave the complex [Ru(CO)3(LSnCl)Cl2] (5) (Scheme 3). The 1H NMR spectrum of 5 showed an AX spin system of CH2N at 3.55 and 4.40 ppm and two signals for CH3 groups at 2.51 and 3.01 ppm, similar to complexes 2-4 (vide supra). The value of δ(119Sn) at 26.3 ppm is again shifted upfield compared to 1. The 13C NMR spectrum revealed signals at 196.6 and 201.1 ppm, proving the presence of carbonyl CO groups. The presence of carbonyl groups was further documented by the IR spectrum of 5 (vibrations at 1963 and 2026 cm-1). To prove the generality of this method for the synthesis of SnII-light platinum metal complexes, the cleavage reaction was also applied to the synthesis of one RhI-SnII complex. The treatment of 1 with [(CΟ)2Rh]2(μ-Cl)2 resulted in the isolation of [Rh(CO)2(LSnCl)Cl] (6) (Scheme 4). The 1H NMR spectrum of 6 revealed the presence of an AB spin system (δA 3.73, δB 3.87) for CH2N and two signals at 2.58 and 2.69 ppm for CH3 groups. The 119 Sn NMR spectrum showed a doublet at 60.8 ppm with

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Organometallics, Vol. 28, No. 16, 2009 Scheme 3

Scheme 4

1

J(119Sn,103Rh) = 880 Hz and clearly proved the formation of a RhI-SnII bond. The 13C NMR spectrum showed the signal of C1 of ligand L as a doublet at 152.3 ppm with 2J(13C, 103 Rh) = 9 Hz, which also provides evidence for the formation of the RhI-SnII bond. Two signals, at 180.6 and 187.2 ppm, in the 13C NMR spectrum, together with two vibrations, at 1951 and 1992 cm-1, in the IR spectrum, indicate the presence of two carbonyl CO groups bound to RhI. These data define the square-planar geometry of RhI in 6 with two nonequivalent CO groups probably in cis positions. Compound 6 decomposes in THF or CH2Cl2 solution. The precipitation of a brown solid (powder X-ray diffraction analysis was unsuccessful) is accompanied by the formation of a yellow solution, from which the [RhII(LSnCl)2Cl2] (7) was isolated. Compound 7 is a rare example of a mononuclear RhII complex,11 which probably arises from the spontaneous disproportionation of complex 6 (Scheme 5). Similar disproportionation was found in the rhodium(I) bisoxazolinates, where the relevant mononuclear RhII complex and Rh0 were isolated as the final products.12 The molecular structure of complex 7 is shown in Figure 3, and selected bond distances and bond angles are listed in the figure caption. Compound 7 adopts the trans planar geometry similar to complexes (Ph3P)2RhCl2 and (i-Pr3P)2RhCl2.13 However, the Rh-Cl bond [2.469(3) A˚] in 7 is longer than the same bond found in (Ph3P)2RhCl2 [2.298(1) A˚] and (i-Pr3P)2RhCl2 [2.428(4) A˚].13 This unique distortion from the ideal environment arises from the Sn1-Rh1-Cl2 bond angle, 92.10(4)°. The Sn atom bonded to the Rh is five-coordinated and exhibits a distorted trigonal-bipyramidal configuration, (11) For other examples of mononuclear paramagnetic RhII complexes see: (a) Pandey, K. K. Coord. Chem. Rev. 1992, 121, 1. (b) DeWit, D. G. Coord. Chem. Rev. 1996, 147, 209. (c) Gerisch, M.; Krumper, J. R.; Bergman, R. G.; Tilley, T. D. J. Am. Chem. Soc. 2001, 123, 5818. (d) Collman, J. P.; Boulatov, R. J. Am. Chem. Soc. 2000, 122, 11812. (12) (a) Willems, S. T. H; Russcher, J. C.; Budzelaar, P. H. M.; de Bruin, B.; de Gelder, R; Smits, J. M. M.; Gal, A. W. Chem. Commum. 2002, 148. (b) Martin, B.; McWhinnie, W. R.; Waind, G. M. J. Inorg. Nucl. Chem. 1961, 23, 207. (c) Alternatively, the brown solid may also be Sn(0), since the stannylene 1 can oxidize Rh(I) to Rh(II) giving Sn(0). (13) (a) Harlow, R. L.; Thorn, D. L.; Baker, R. T.; Jones, N. L. Inorg. Chem. 1992, 31, 993. (b) Ogle, C. A.; Masterman, T. C.; Hubbard, J. L. J. Chem. Soc, Chem. Commun. 1990, 1733. (c) Dunbar, K. R.; Haefner, J. S. C. Inorg. Chem. 1992, 31, 3676. (14) (a) Kilian, M.; Wadepohl, H.; Gade, L. H. Dalton Trans. 2008, 582. (b) Adams, R. D.; Captain, B.; Smith, J. L.; Hall, M. B.; Beddie, C. L.; Webster, C. E. Inorg. Chem. 2004, 43, 7576. (c) Chan, D. M. T.; Marder, T. B. Angew. Chem., Int. Ed. 1988, 27, 442. (c) Kilian, M.; Wadepohl, H.; Gade, L. H. Organometallics 2007, 26, 3076. (d) Kilian, M.; Wadepohl, H.; Gade, L. H. Organometallics 2008, 27, 524. (e) Joosten, D.; Weissinger, I.; Kirchmann, M.; Maichle-Mossmer, C.; Schappacher, F. M.; P€ottgen, R.; Wesemann, L. Organometallics 2007, 26, 5696.

Martincov a et al. Scheme 5

with the N1 and N2 atoms occupying the axial positions and the Cl1, C1, and Rh1 atoms occupying the equatorial positions. The Rh1-Snl bond distance, 2.5485(4) A˚, is comparable to those found in RhI-SnII complexes (in the range 2.554-2.633 A˚).14 Electronic spectra of 6 and 7 were recorded in CH2Cl2 and differ substantially. Whereas compound 6 absorbs minimally in the visible region, complex 7 exhibits a band at 412 nm and a shoulder at 476 nm, which can be assigned to the d-d transition of the low-spin RhII (d7) mononuclear complex (see Supporting Information). The UV region showed an absorption maximum around 240 nm and a significant decrease in the ε value of the band at 360 nm in complex 7.

Experimental Section General Methods. The starting compound 1 was prepared according to the literature.4c All reactions were carried out under argon, using standard Schlenk techniques. The starting complexes [(η3-C3H5)Pd]2(μ-Cl)2, [(η6-benzene)RuCl]2(μ-Cl)2, [(η6-cymene)RuCl]2(μ-Cl)2, [(CΟ)3RuCl]2(μ-Cl)2, and [(CΟ)2Rh]2(μ-Cl)2 were purchased from Sigma Aldrich. Solvents were dried by standard methods, distilled prior to use. The 1 H, 13C, and 119Sn NMR spectra were recorded at ambient temperature with a Bruker Avance 500 spectrometer. The chemical shifts δ are given in ppm and referenced to external SiMe4 (1H, 13C) or SnMe4 (119Sn). The IR spectra were recorded on a Perkin-Elmer 684 spectrometer (in CH2Cl2 solution). EPR spectra were measured with a ERS 221 (ZWG Berlin) apparatus in microwave X-band (∼9.5 GHz). The apparatus was gauged on the DPPH value (g = 2.0036 ( 2).15 Solid samples were measured in quartz capillaries (width 0.5 mm) at rt. General Procedure for Preparation of PdII-SnII or RuII-SnII Complexes 2-5. A solution of 1 and the transition metal precursor (0.5 equiv) in THF (40 mL) was stirred for 24 h. The resulting mixture was filtered and evaporated to dryness, and the solid residue was washed with hexane or pentane, giving complexes 2-5 as colored solids. Synthesis of [Pd(η3-C3H5)(LSnCl)Cl] (2). The reaction of 1 (345 mg, 1 mmol) with [(η3-C3H5)Pd]2(μ-Cl)2 (276 mg, 0.5 mmol) provided yellow solid 2 (yield 610 mg, 98%). For 2: mp 145 °C (dec). Anal. Calcd for C15H25Cl2N2PdSn (529.38): C, 34.03; H, 4.76. Found: C, 34.00; H, 4.74. 1H NMR (C6D6, 500.13 MHz): δ 1.50 (d, 1H, CH2 (anti)), 2.20 (d, 1H, CH2 (anti)), 2.23 (s, 6H, NCH3), 2.43 (s, 6H, NCH3), 3.52 (AX system, 2H, CH2N), 3.66 (d, 1H, CH2 (syn)), 3.91 (AX system, 2H, CH2N), 4.61 (d, 1H, CH2 (syn)), 4.87 (m, 1H, CH), 6.95 (d, 2H, ArH), 7.19 (t, 1H, ArH). 13C NMR (C6D6, 125.77 MHz): δ 46.7 (NCH3), 47.3 (Cterm), 65.2 (CH2N), 78.7 (Cterm), 112.5 (Cmeso), 126.6, 130.5, 145.0, 153.1, 119Sn NMR (C6D6, 186.49 MHz): δ 126.0. Synthesis of [Ru(η6-benzene)(LSnCl)Cl2] (3). The reaction of 1 (300 mg, 0.87 mmol) with [(η6-benzene)RuCl]2(μ-Cl)2 (217 mg, 0.43 mmol) provided red solid 3 (yield 370 mg, 80%). For 3: mp 182-184 °C. Anal. Calcd for C18H26Cl3N2RuSn (596.54): C, 36.24; H, 4.39. Found: C, 36.21; H, 4.36. 1H NMR (C6D6, 500.13 MHz): δ 2.48 (s, 12H, NCH3), 3.06 (AX system, 2H, CH2N), 4.35 (AX system, 2H, CH2N), 5.28 (s, 6H, C6H6), 6.82 (15) Krzystek, J.; Sienkiewicz, A.; Pardi, L.; Brunel, L. C. J. Magn. Reson. 1997, 125, 207.

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Figure 3. ORTEP view of 7. The thermal ellipsoids are drawn with 50% probability. Hydrogen atoms together with a molecule of CHCl3 are omitted for clarity. Selected bond distances (A˚) and angles (deg): Sn1-C1 2.118(4), Sn1-Cl1 2.4192(12), Sn1-N1 2.468(4), Sn1-N2 2.503(3), Sn1-Rh1 2.5485(4), Rh1-Cl2 2.469(3), C1-Sn1-Cl1 100.76(12), N1-Sn1-N2 147.48(12), C1-Sn1-Rh1 139.99(12), Cl1-Sn1-Rh1 118.99(3), Cl2-Rh1-Sn1 92.10(4). (d, 2H, ArH), 7.15 (t, 1H, ArH). 13C NMR (C6D6, 125.77 MHz): δ 46.8 (NCH3), 67.7 (CH2N), 84.1 (C6H6), 127.9, 130.3, 143.6, 146.6. 119Sn NMR (C6D6, 186.49 MHz): δ -109.9. Synthesis of [Ru(η6-cymene)(LSnCl)Cl2] (4). The reaction of 1 (345 mg, 0.99 mmol) with [(η6-cymene)RuCl]2(μ-Cl)2 (306 mg, 0.49 mmol) provided red solid 4 (yield 553 mg, 85%). For 4: mp 195 °C (dec). Anal. Calcd for C22H34Cl3N2RuSn (652.55): C, 40.49; H, 5.25. Found: C, 40.46; H, 5.22. 1H NMR (CDCl3, 500.13 MHz): δ 1.36 (d, J(H,H) ≈ 7 Hz, 6H, CH(CH3)2), 2.24 (s, 3H, CH3{ring}), 2.64 (s, 12H, NCH3), 2.93 (sept, 1H, CH(CH3)2), 3.38 (AX system, 2H, CH2N), 4.38 (AX system, 2H, CH2N), δa 5.58, δb 5.67 (dd, J(H,H) ≈ 7 Hz, 4H, C2,3,5,6H{ring}), 7.01 (d, 2H, ArH), 7.24 (t, 1H, ArH). 13C NMR (CDCl3, 125.77 MHz): δ 18.6 (CH3{ring}), 25.6 (CH(CH3)2), 31.6 (CH(CH3)2), 46.7 (NCH3), 68.0 (CH2N), 82.2 (C2,6{ring}), 83.8 (C3,5{ring}), 95.2 (C4{ring}), 104.9 (C1{ring}), 125.3, 130.1, 144.0, 148.2. 119Sn NMR (CDCl3, 186.49 MHz): δ -128.2. Synthesis of [Ru(CO)3(LSnCl)Cl2] (5). The reaction of 1 (280 mg, 0.81 mmol) with [(CΟ)3RuCl]2(μ-Cl)2 (207 mg, 0.41 mmol) provided orange solid 5 (yield 342 mg, 70%). For 5: mp 178 °C (dec). Anal. Calcd for C15H20Cl3N2O3RuSn (602.46): C, 29.91; H, 3.35. Found: C, 29.88; H, 3.32. 1H NMR (CDCl3, 500.13 MHz): δ 2.51 (s, 6H, NCH3), 3.01 (s, 6H, NCH3), 3.55 (AX system, 2H, CH2N), 4.40 (AX system, 2H, CH2N), 7.07 (d, 2H, ArH), 7.28 (t, 1H, ArH). 13C NMR (CDCl3, 125.77 MHz): δ 46.6 (NCH3), 47.3 (NCH3), 66.0 (CH2N), 125.7, 130.5, 144.1, 149.4, 196.6, 201.1. 119Sn NMR (CDCl3, 186.49 MHz): δ 26.4. IR (CH2Cl2): ν (cm-1) 1963 vs, 2026 vs. Synthesis of [Rh(CO)2(LSnCl)Cl] (6) and [Rh(LSnCl)2Cl2] (7). [(CΟ)2Rh]2(μ-Cl)2 (98 mg, 0.26 mmol) dissolved in THF (20 mL) was added to a THF solution (10 mL) of 1 (175 mg, 0.52 mmol) at -78 °C and stirred for 2 h. The resulting yellow solution was evaporated, and the solid residue was washed with hexane (10 mL), giving 240 mg (90% yield) of 6 as a yellow solid. Alternatively, when the yellow solution was warmed to rt for 24 h, precipitation of a brown solid was observed. The resulting mixture was filtered and evaporated to dryness, and the yellow solid residue was redissolved in CH2Cl2 (2 mL). Slow evaporation of this solution gave 40 mg (18% yield) of 7 as a crystalline material suitable for X-ray diffraction analysis. For 6: 1H NMR (CDCl3, 500.13 MHz): δ 2.58 (s, 6H, NCH3), 2.69 (s, 6H, NCH3), δa 3.73, δb 3.87 (dd, 4H, CH2N), 7.11 (d, 2H, ArH), 7.26 (t, 1H, ArH). 13C NMR (CDCl3, 125.77 MHz): δ 46.0 (NCH3), 46.6 (NCH3), 64.4 (CH2N), 67.7 (CH2N), 124.9, 129.6, 144.1, 152.3 (d, 2J(103Rh,13C) = 9 Hz, 1J(119Sn,13C) = 160 Hz), 180.6 (d, 1J(103Rh,13C) = 53 Hz), 187.5 (d, 1J(103Rh,13C) = 53 Hz). 119Sn NMR (CDCl3, 186.5 MHz): δ

60.8 (d, 1J(119Sn,103Rh) = 880 Hz). IR (CH2Cl2): ν (cm-1) 1951 vs, 1992 vs. For 7: mp 188 °C (dec). Anal. Calcd for C24H38Cl4N4RhSn2 (864.7): C, 33.34; H, 4.43. Found: C, 33.08; H, 4.22. λmax/nm (ε/dm3 mol-1 cm-1) (CH2Cl2): 240 (19 400), 360 (4700), 412 (330), 476 (130). EPR: powder, single asymmetric peak g=2.038. Crystallography. Single crystals of 2, 4, and 7 were obtained by slow evaporation from dichloromethane (for 2) or chloroform (for 4 and 7) solutions. Crystals were mounted on a glass fiber with an inert viscous oil and measured on a KappaCCD diffractometer with a CCD area detector by monochromatized MoKradiation (=0.71073 A˚) at 150(2) K. The details pertaining to the data collection and refinement for crystals are given in Table 1 (see Supporting Information). The numerical12 absorption correction from the crystal shape was applied to all crystals. The structures were solved by the direct method (SIR9716) and refined by a full-matrix least-squares procedure based on F2 (SHELXL9717). Hydrogen atoms were fixed into 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 with C-H= 0.96, 0.97, and 0.93 A˚ for methyl, methylene, and hydrogen atoms in aromatic rings or allyl groups, respectively. The final difference maps displayed no peaks of chemical significance, as the highest peaks and holes are in close vicinity (∼1 A˚
) of heavy atoms. There is a disordered allyl group in compound 2. This disorder was solved by splitting of atom C14 into two positions (in the plane of the allyl moiety) with the half-occupancy of electron density for each carbon, C14A and C14B, respectively. The hydrogen atoms for this group were idealized only for the arrangement with C14A. In the structure of 7, there is a disorder of the chlorine atom in the direction of the Rh-Cl bond. The application of an ISOR restraint or EXYZ or EADP constraints did not provide a better model.

Acknowledgment. The authors wish to thank the Grant Agency of the Czech Republic (project no. 203/07/0468) and The Ministry of Education of the Czech Republic (LC523) for financial support. Supporting Information Available: Visible region of the electronic absorption spectra of the CH2Cl2 solutions of complex 6 and 7 is shown in Figure 4. The details pertaining to the (16) Sheldrick, G. M. SHELX-97 program package; University of Goettingen, 1997. (17) Sheldrick, G. M. SHELXTL V 5.10; Bruker AXS Inc.: Madison, Wl, 1997.

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data collection and refinement for crystals used for X-ray are given in Table 1. Crystallographic data for compounds 2, 4, and 7 have been deposited with the Cambridge Crystallographic Data Centre, CCDC nos. 720809-720811. Further details on

Martincov a et al. the structure determination of compounds 2, 4, and 7, including atomic coordinates, anisotropic displacement parameters, and geometric data, are available free of charge via the Internet at http://pubs.acs.org.