Organometallics 2009, 28, 4221–4224 DOI: 10.1021/om900174q
4221
N,S- and N,O-Substituted Stannylenes: Preparation and X-ray Diffraction Studies Alexander V. Zabula, Tania Pape, Florian Hupka, Alexander Hepp, and F. Ekkehardt Hahn* Institut f€ ur Anorganische und Analytische Chemie der Westf€ alischen Wilhelms-Universit€ at M€ unster, Corrensstrasse 36, D-48149 M€ unster, Germany Received March 4, 2009 Summary: The reaction of 2 equiv of Sn[N(SiMe3)2]2 with 1,2-benzodithiol gave the unstable N,S-substituted bis-stannylene 1, which decomposes in solution to yield Sn[N(SiMe3)2]2 and the S-heterocyclic stannylene 2. An X-ray diffraction analysis with crystals of 1 revealed the presence of two threecoordinated tin atoms with an S,S,N donor set and strong intramolecular Sn-S interactions. The related reaction of 3 equiv of Sn[N(SiMe3)2]2 with 2 equiv of 1,2-benzodiol gave the tris-stannylene 3 with two different types of SnII atoms. An X-ray diffraction analysis with crystals of 3 shows the central tin(II) atom to be coordinated by four oxygen donors while two additional peripheral tin(II) atoms are three-coordinated by a mixed O,O,N donor set. The central O4Sn core in 3 is strongly pyramidalized. In contrast to bis-stannylene 1 trisstannylene 3 is stable both in the solid state and in solution. Stannylenes are tin analogues of carbenes1 and as such represent an important class of tin(II) compounds.2 Similarly to carbenes, they are highly reactive species which can be stabilized by the coordination of different heteroatoms to the divalent tin atom or/and by the incorporation of the tin atom
into an aromatic system.3 Due to the presence of a free electron pair and a vacant p orbital at the tin atom they function as σ donors and π acceptors in their transition-metal complexes.4 One important and interesting class of the stable divalent tin derivatives is formed by the N-heterocyclic stannylenes.3,5 Previously we have described the preparation and coordination chemistry of benzannulated mono- and polydentate N-heterocyclic germylenes,6 stannylenes,7 and plumbylenes8 and their complexes. The benzannulated N-heterocyclic stannylenes can be prepared by a transamination reaction between Sn[N(SiMe3)2]24c and an appropriate N,N0 -dialkyl-1,2-diaminobenzene.5c,7 In this contribution we describe the isolation and molecular structures of some unusual reaction products obtained from the transamination reaction between Sn[N(SiMe3)2]2 and sulfur and oxygen analogues of 1,2-diaminobenzene.
Results and Discussion The reaction of 1 equiv of 1,2-benzodithiol with 2.05 equiv of Sn[N(SiMe3)2]2 at -35 C in THF gave the N,S-substituted bis-stannylene 1 (Scheme 1). Bis-stannylene 1 can be crystallized at -40 C from hexane as yellow crystals. It is, however, unstable in solution and decomposes rapidly to give Sn[N(SiMe3)2]2 and the S-heterocyclic stannylene 2, which precipitates as a white crystalline solid from the reaction solution. The instability of 1, even in the presence of a large excess of Sn[N(SiMe3)2]2, prevented the collection of NMR spectroscopic data for the compound. Compound 2 was found to be insoluble in all common organic solvents.9
*To whom correspondence should be addressed. E-mail: fehahn@ uni-muenster.de. (1) (a) Hahn, F. E.; Jahnke, M. C. Angew. Chem., Int. Ed. 2008, 47, 3122. (b) Kaufhold, O.; Hahn, F. E. Angew. Chem., Int. Ed. 2008, 47, 4057. (c) Hahn, F. E. Angew. Chem., Int. Ed. 2006, 45, 1348. (d) Bourissou, D.; Guerret, O.; Gabbaı¨ , F. P.; Bertrand, G. Chem. Rev. 2000, 100, 39. (2) (a) Neumann, W. P. Chem. Rev. 1991, 91, 311. (b) Takeda, N.; Tokitoh, N.; Okazaki, R. Sci. Synth. 2003, 5, 311. (c) Tokitoh, N.; Okazaki, R. Coord. Chem. Rev. 2000, 210, 251. (3) (a) Baumeister, U.; Hartung, H.; Jurkschat, K.; Tzschach, A. J. Organomet. Chem. 1986, 304, 107. (b) Zemlyansky, N. N.; Borisova, I. V.; Kuznetsova, M. G.; Khustalev, V. N.; Ustynyuk, Y. A.; Nechaev, M. S.; Lunin, V. V.; Barrau, J.; Rima, G. Organometallics 2003, 22, 1675. (c) Mansell, S. M.; Russell, C. A.; Wass, D. F. Inorg. Chem. 2008, 47, 11367. (d) Berends, T.; Iovkova, L.; Bradtm€ oller, G.; Oppel, I.; Sch€ urmann, M.; Jurkschat, K. Z. Anorg. Allg. Chem. 2009, 635, 369. (e) Zabula, A. V.; Hahn, F. E. Eur. J. Inorg. Chem. 2008, 5165. (4) (a) Lappert, M. F.; Rowe, R. S. Coord. Chem. Rev. 1990, 100, 267. (b) Holt, M. S.; Wilson, W. L.; Nelson, J. H. Chem. Rev. 1989, 89, 11. (c) Lappert, M. F.; Power, P. P. J. Chem. Soc., Dalton Trans. 1985, 51. (d) Veith, M.; Recktenwald, O. Top. Curr. Chem. 1982, 104, 1. (e) Fjeldberg, T.; Hope, H.; Lappert, M. F.; Power, P. P.; Thorne, A. J. J. Chem. Soc., Chem. Commun. 1983, 639. (5) (a) Veith, M. Z. Naturforsch. 1978, 33b, 7. (b) Veith, M. Z. Naturforsch. 1978, 33b, 1. (c) Braunschweig, H.; Gehrhus, B.; Hitchcock, P. B.; Lappert, M. F. Z. Anorg. Allg. Chem. 1995, 621, 1922. (d) Heinicke, J.; Oprea, A.; Kindermann, M. K.; Karpati, T.; Nyulaszi, L.; Veszpremi, T. Chem. Eur. J. 1998, 4, 541. (e) Gans-Eichler, T.; Gudat, D.; Nieger, M. Angew. Chem., Int. Ed. 2002, 41, 1888. (f) Drost, C.; Hitchcock, P. B.; Lappert, M. F. Angew. Chem., Int. Ed. 1999, 38, 1113. (g) Bazinet, P.; Yap, G. P. A.; DiLabio, G. A.; Richenson, D. S. Inorg. Chem. 2005, 44, 4616. (h) Rasika Dias, H. V.; Jin, W. J. Am. Chem. Soc. 1996, 118, 9123. (i) Ayers, A. E.; Rasika Dias, H. V. Inorg. Chem. 2002, 41, 3259.
(6) (a) Zabula, A. V.; Hahn, F. E.; Pape, T.; Hepp, A. Organometallics 2007, 26, 1972. (b) Hahn, F. E.; Zabula, A. V.; Pape, T.; Hepp, A. Eur. J. Inorg. Chem. 2007, 2405. (c) Hahn, F. E.; Zabula, A. V.; Pape, T.; Hepp, A. Z. Anorg. Allg. Chem. 2008, 634, 2397. (7) (a) Hahn, F. E.; Wittenbecher, L.; K€ uhn, M.; L€ ugger, T.; Fr€ ohlich, R. J. Organomet. Chem. 2001, 617-618, 629. (b) Hahn, F. E.; Wittenbecher, L.; Le Van, D.; Zabula, A. V. Inorg. Chem. 2007, 46, 7662. (c) Zabula, A. V.; Pape, T.; Hepp, A.; Schappacher, F. M.; Rodewald, U. C.; P€ ottgen, R.; Hahn, F. E. J. Am. Chem. Soc. 2008, 130, 5648. (d) Zabula, A. V.; Pape, T.; Hepp, A.; Hahn, F. E. Organometallics 2008, 27, 2756. (e) Zabula, A. V.; Pape, T.; Hepp, A.; Hahn, F. E. Dalton Trans. 2008, 5886. (f) Hahn, F. E.; Zabula, A. V.; Pape, T.; Hepp, A.; Tonner, R.; Haunschild, R.; Frenking, G. Chem. Eur. J. 2008, 14, 10716. (8) Hahn, F. E.; Heitmann, D.; Pape, T. Eur. J. Inorg. Chem. 2008, 1039. (9) (a) Zemlyanskii, N. N.; Borisova, I. V.; Nechaev, M. S.; Khrustalev, V. N.; Lunin, V. V.; Antipin, M. Y.; Ustynyuk, Y. A. Russ. Chem. Bull., Int. Ed. 2004, 53, 980. (b) Zemlyanskii, N. N.; Borisova, I. V.; Kuznetsova, M. G.; Khrustalev, E. N.; Antipin, M. Y.; Ustynyuk, Y. A.; Lunin, E. E.; Eaborn, C.; Hill, M. S.; Smith, J. D. Russ. J. Org. Chem. 2003, 39, 491. (c) Harrison, P. G.; Stobart, S. R. Inorg. Chim. Acta 1973, 7, 306. (d) Honnick, W. D.; Zuckerman, J. J. Inorg. Chem. 1978, 17, 501.
r 2009 American Chemical Society
Published on Web 06/17/2009
pubs.acs.org/Organometallics
4222
Organometallics, Vol. 28, No. 14, 2009
Figure 1. Molecular structure of 1 (50% probability ellipsoids). Selected bond lengths (A˚) and angles (deg): Sn1-S1=2.7076(4), Sn1-S2=2.6978(4), Sn1-N1=2.1032(11), Sn2-S1=2.6931(4), Sn2-S2 = 2.7204(4), Sn2-N2 = 2.0952(12); S1-Sn1-S2 = 72.285(11), S1-Sn1-N1=97.71(3), S2-Sn1-N1=102.15(3), S1-Sn2-S2 = 72.285(11), S1-Sn2-N2 = 93.88(3), S2-Sn2N2=104.39(3). Scheme 1. Formation and Decomposition of Bis-Stannylene 1
Bis-stannylene 1 is apparently an intermediate in the formation of 2. A similar bis-stannylene has been postulated as an intermediate in the trimolecular transamination reaction between 2 equiv of Sn[N(SiMe3)2]2 and 1 equiv of N,N0 -dialkyl1,2-diaminobenzenes. This heteroleptic bis-stannylene could not be isolated but was proposed to undergo a pericyclic transformation to give the N-heterocyclic stannylene and 1 equiv of Sn[N(SiMe3)2]2.5c An X-ray diffraction study with crystals of 1 (Figure 1) now demonstrates the formation of a
Zabula et al.
bis-stannylene intermediate with two three-coordinated tin atoms during the formation of the S-heterocyclic stannylene 2. Two tin atoms in 1 are located above and below the C6H4S2 plane. The coordination geometry around the tin atoms is best described as a trigonal pyramid with the basal plane made up from atoms S1, S2, and N1 or N2 and the tin atom at the apex. The Sn-N bond lengths in 1 (2.1032(11) and 2.0952(12) A˚) and Sn[N(SiMe3)2]2 (2.096 (1) and 2.088(6) A˚)4e are only slightly different. The interatomic Sn-S separations in 1 fall in the range 2.6931(4)2.7204(4) A˚. They are longer than covalent SnII-S bonds (2.5-2.6 A˚)3a and significantly shorter than S 3 3 3 SnII donor-acceptor interactions (2.9-3.7 A˚).3a,9 A different product, tris-stannylene 3, has been isolated from the reaction of 1,2-benzodiol with Sn[N(SiMe3)2]2 (Scheme 2). In contrast to bis-stannylene 1, compound 3 is stable both in solution and in the solid state. Only trisstannylene 3 was isolated from the reaction of 1 equiv of 1,2-(HO)2C6H4 and 2 equiv of Sn[N(SiMe3)2]2. Tris-stannylene 3 can be formed in the reaction mixture by the intramolecular cyclization of a hypothetical linear trisstannylene (Scheme 2, reaction a) or by the reaction of the oxygen analogue of 1 with an O-heterocyclic stannylene (Scheme 2, reaction b). Two signals were detected in the 119Sn NMR spectrum of 3 in toluene at δ 6.9 and -388.5 ppm (Figure 2). The broad signal at δ 6.9 ppm corresponds to the three-coordinated tin atoms with the O2N donor set. The sharp resonance signal of the central tetracoordinated tin atom appears at δ -388.5 ppm. The signal at δ -388.5 ppm shows reduced coupling constants between the 117Sn and/or 119Sn nuclei of 2J(119Sn-119Sn) = 104.8 Hz and 2J(119Sn-117Sn)=100.0 Hz. The molecular structure of 3 was determined by an X-ray diffraction study. The asymmetric unit contains two essentially identical molecules of 3, one of which is depicted in Figure 3. Two tin atoms (Sn2 and Sn3) in tris-stannylene 3 are coordinated by two oxygen and one nitrogen atom, exhibiting a trigonal-pyramidal coordination geometry. The central tin atom Sn1 is coordinated by four oxygen atoms in a square-pyramidal fashion. Two short (Sn1-O1=2.205(2) A˚
Scheme 2. Preparation of Tris-Stannylene 3 and Possible Mechanisms (a and b) for Its Formation
Note
Figure 2.
Organometallics, Vol. 28, No. 14, 2009
119
4223
Sn NMR spectrum of tris-stannylene 3 measured in toluene.
and Sn1-O4=2.224(2) A˚) and two longer (Sn1-O2=2.268(2) A˚ and Sn1-O3=2.255(2) A˚) bond lengths are observed for the central O4Sn core, indicating the presence of slightly different Sn-O bonds. The Sn-O separations fall in the range previously desribed for polymeric (SnO)¥ (Sn-O separation 2.224(8) A˚)10 or the stannylene complex of tin (II) monoxide (2.079(2)-2.135(2) A˚).7c The N(SiMe3)2 substituents at atoms Sn2 and Sn3 point in the same direction (Figure 3, bottom). This type of syn orientation has been observed previously for related compounds.3d
Experimental Section General Comments. All manipulations were carried out under an argon atmosphere using standard Schlenk or glovebox techniques. Solvents were dried over sodium/benzophenone under argon and were freshly distilled prior to use. Toluene-d8 was dried over Na/K alloy. 1,2-Benzodithiol was prepared as previously described.11 1H, 13C, 29Si, and 119Sn NMR spectra were measured on a Bruker AC-400 spectrometer at 400 MHz for 1H, 100.6 MHz for 13C, 79.5 MHz for 29Si, and 149.2 MHz for 119Sn and are reported relative to TMS or Me4Sn. Bis-Stannylene 1. A solution of 1,2-benzodithiol (40 mg, 0.282 mmol) in THF (2 mL) was slowly added to a solution of Sn[N(SiMe3)2]2 (254 mg, 0.577 mmol) in THF (3 mL) at -35 C. The reaction mixture was warmed to 0 C while all volatiles were removed in vacuo. Chilled hexane (3 mL) was added to the obtained solid, and the resulting solution was filtered. The filtrate was cooled to -40 C and filtered again. After concentration of the solution in vacuo to 1 mL, a few drops of toluene were added. Yellow crystals of 1 were obtained after cooling of this solution to -45 C for 2 days. Yield: 108 mg (0.158 mmol, 55%). The crystals are thermally sensitive and rapidly decompose at ambient temperature within a few minutes. In solution at ambient temperature, decomposition of 1 yields stannylene 2 and Sn[N(SiMe3)2]2 (identified by 1H and 13C NMR spectroscopy) in addition to unidentified products. The rapid reaction of 1 to yield 2 at temperatures above -40 C prevented the further spectroscopic or microanalytical characterization of compound 1. Stannylene 2. A solution of 1,2-benzodithiol (80 mg, 0.564 mmol) in THF (4 mL) was added to a solution of Sn[N(SiMe3)2]2 (254 mg, 0.577 mmol) in THF (6 mL) at ambient temperature. The reaction mixture was stirred at ambient temperature for 24 h. Subsequently all volatiles were removed. The solid residue was suspended in THF (3 mL) and filtered. The solid obtained was again washed with THF (3 mL). Compound 2 was obtained as a white solid which was insoluble in all common solvents. Yield: 100 mg (0.4 mmol, 71%). (10) Pannetier, J.; Denes, G. Acta Crystallogr. 1980, B36, 2763. (11) Maiolo, F; Testaferri, L.; Tiecco, M.; Tingoli, M. J. Org. Chem. 1981, 46, 3070.
Figure 3. Molecular structure of one of the two independent molecules of 3 in the asymmetric unit (50% probability ellipsoids). Selected bond lengths (A˚) and angles (deg): Sn1-O1 = 2.205(2), Sn1-O2 = 2.268(2), Sn1-O3 = 2.255(2), Sn1-O4 = 2.224(2), Sn2-O1 = 2.194(2), Sn2-O3 = 2.213(2), Sn2N1 = 2.101(2), Sn3-O2 = 2.181(2), Sn3-O4 = 2.217(2), Sn3N2=2.095(2); O1-Sn1-O2 = 71.91(6), O1-Sn1-O3 = 72.43 (7), O1-Sn1-O4= 106.58(7), O2-Sn1-O3=117.80(7), O2Sn1-O4 = 72.24(7), O3-Sn1-O4 = 72.48(6), O1-Sn2-O3 = 73.45(7), O1-Sn2-N1 = 89.64(8), O3-Sn2-N1 = 85.08(7), O2-Sn3-O4 = 72.99(7), O2-Sn3-N2 = 85.65(8), O4-Sn3N2=89.61(8). MS (EI, 70 eV): m/z (%) 260 (100) [M]+ (correct isotope distribution). Anal. Calcd: C, 27.83; H, 1.56. Found: C, 28.02; H, 1.70. Tris-Stannylene 3. A solution of Sn[N(SiMe3)2]2 (600 mg, 1.36 mmol) in THF (5 mL) was treated with a THF solution (2 mL) of 1,2-(HO)2C6H4 (100 mg, 0.91 mmol). The reaction mixture was stirred at ambient temperature for 24 h. Subsequently the solvent and all other volatiles were removed in vacuo. A beige solid was obtained, which was washed with n-hexane and recrystallized from toluene to give tris-stannylene 3 as colorless plates. Yield: 233 mg (0.261 mmol, 58%). 1H NMR (400 MHz, toluene-d8): δ 6.68-6.65 (m, 4H, Ar H), 6.61-6.58
4224
Organometallics, Vol. 28, No. 14, 2009
Zabula et al.
(m, 4H, Ar H), 0.33 (s, 36H, Si(CH3)3). 13C NMR (100.6 MHz, toluene-d8): δ 149.5 (Ar Cipso), 121.5 (Ar Cmeta), 117.2 (Ar Cortho, reduced coupling constants 3J(13C-119Sn)=14.1 and 20.3 Hz, 3J (13C-117Sn) = 13.5 and 19.3 Hz), 6.0 (Si(CH3)3, 1J(13C-29Si) = 54.9 Hz, 3J(13C-119Sn)=16.7 Hz (reduced coupling constant), 3J (13C-117Sn)=15.9 Hz (reduced coupling constant)). 29Si NMR (79.5 MHz, toluene-d8): δ -0.98 (1J(29Si-13C)=54.9 Hz). 119Sn NMR (149.2 MHz, toluene-d8): δ 6.9, -388.5 (reduced coupling constants 2J(119Sn-119Sn)=104.8 Hz and 2J(119Sn-117Sn)=100.0 Hz). Anal. Calcd: C, 32.28; H, 4.97; N, 3.14. Found: C, 32.42; H, 5.15; N, 3.00. X-ray Diffraction Studies. X-ray diffraction data for 1 and 3 were collected with a Bruker AXS APEX CCD diffractometer equipped with a rotating anode at 153(2) K using graphitemonochromated Mo KR radiation (λ=0.71073 A˚). Diffraction data were collected over the full sphere and were corrected for absorption. The data reduction was performed with the Bruker SMART12 program package. Structure solutions were found with the SHELXS-97 package13 using the heavy-atom method and were refined with SHELXL-9714 against F2 using first isotropic and later anisotropic thermal parameters for all
non-hydrogen atoms. Hydrogen atoms were added to the structure models on calculated positions. Crystal data for 1. C18H40N2S2Si4Sn2, M = 698.38, monoclinic, P21/c, a=13.3768(4) A˚, b=16.0331(5) A˚, c=13.8670(4) A˚, β = 91.4630(4), V = 2973.11(15) A˚3, Z = 4, T = 153(2) K, Dcalcd=1.560 g cm-3, R=0.0160, Rw=0.0381 for 7305 observed intensities (I g 2σ(I)) collected in the range 3.0 e 2θ e 58.3. Crystal data for 3. C24H44N2O4Si4Sn3, M = 893.04, triclinic, P1, a=12.6118(4) A˚, b=16.8353(5) A˚, c=17.5351(5) A˚, R=106.060(1), β=90.564(1), γ=100.265(1), V=3513.7(2) A˚3, Z=4, T=153(2) K, Dcalcd=1.688 g cm-3, R=0.0272, Rw= 0.0563 for 15 867 observed intensities (I g 2σ(I)) collected in the range 2.4 e 2θ e 58.3. The asymmetric unit contains two almost identical molecules of 3.
(12) SMART; Bruker AXS, Madison, WI, 2000. (13) Sheldrick, G. M. SHELXS-97. Acta Crystallogr. 1990, A46, 467. (14) Sheldrick, G. M. SHELXL-97; Universit€at G€ ottingen, G€ ottingen, Germany, 1997.
Supporting Information Available: CIF files giving X-ray crystallographic data for compounds 1 and 3. This material is available free of charge via the Internet at http://pubs.acs.org.
Acknowledgment. We thank the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie for financial support. A.V.Z. and F.H. thank the NRW Graduate School of Chemistry M€ unster for a predoctoral grant.
