2348 Organometallics zyxwvu 1992, 11, 2348-2350 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON h zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 3a:L=PMe3 3b: L zyxwvutsrqpon = PPh3 (T = zyxwvuts 65T) 3c:L=CN' The retention of the [Ni(S,C)] core in the course of cleavage reactions according to zyxwvut eq 2 demonstrata the high stability of the Ni-C(carbene) bond. It can be attributed to several facts. The carbene C atom carries two N sub- stituents, as in the case of "Wanzlick"loand "Arduengo" carbenes" or in Lappert-type carbene complexes.12 Furthermore, the carbene donor is part of a tridentate ligand, and the Ni center in the [Ni(S2C)]fragment is coordinated by two thiolate donors. These donors can act, via their lone pairs, as *-donors to the nickel center, in- creasing the electron density at the nickel and as a con- sequence thereof also the *-back-bonding from nickel to the carbene ligand. The *-donor bonds from thiolate donors to nickel and the resulting double-bond character of the Ni-S bonds are indicated by the Ni-S distances (10) (a) Wanzlick, H.-W. Angew. zyxwvutsrqpo Chem. 1962,74,129. (b) Cetinkaya, E.; Hitchcock, P. B.; Jaaim, H. A.; Lappert, M. F.; Spyropoulos, K. J. Chem. SOC., Perkin Trans. 1 1992,561. (11) Arduengo, A. J.; Harlow, R. L.; Kline, M. J. Am. Chem. Soc. 1991, 113, 361. (12) (a) Lappert, M. F.; Dye, P. L. J. Chem. Soc., Dalton Trans. 1977, 2172. (b) Lappert, M. F. J. Organomet. Chem. 1975, 100, 139. (c) Coleman, A. W.; Hitchcock, P. B.; Lappert, M. F.; Maskell, R. K.; MUer, J. C. J. Organomet. Chem. 1985,296,173. within the [Ni(S2C)] fragmenta,which are relatively short when compared with the Ni-S distances in the thiolate bridges. Formation of S+Ni *-donor bonds is expected to reduce the Lewis basicity of the thiolate S atoms, and thie ex- plains, at least partly, the complete inertness of 2 toward protonic acids. While metal thiolate complexes usually react with protonic acids to decoordinate the thiolate lig- and~,~~ 2 is stable even toward concentrated H2S04, aqueous HCl, or solutions of gaseous HC1 in boiling THF. The present work has shown that highly stable Ni(I1) carbene complexes can formed by reaction of C1 sources, thiolate amine ligands, and Ni(1I) salta. The question as to whether analogous reactions occur in the course of C02/C0 conversion or CH4 formation in CO de- hydrogenases still remains open. Further investigations have shown that palladium and platinum form analogous complexes. Acknowledgment. We gratefully acknowledge the support of this research by the Deutache Forschungsge- meinschaft, the Fonds der Chemischen Industrie, and the Bundesministerium fur Forschung und Technologie. Supplementary Material Available: Tablea of crystal data and details of the structure solution and refinement, positional and thermal parametera, and bond diatancea and anglea (6 pages). Ordering information is given on any current maathead page. OM9201340 (13) (a) Sellmann, D.; ReieSer, W. 2. Natwforsch. 1984,39E, 1268. (b) Sellmann, D.; Reiaeer, W. J. Organomet. Chem. 1986,294,333. Synthesis, Structure, and Reactivlty of the First Dlazagermocines Santiago Garda Granda,§ and Pilar Pertierras Departamento de Qdmica Olganometilica and Departamento de Qdmica F ha y Anakica, Facultad de Qdmica, UniversMad de zyxwvut OvW, 330714vied0, Spain Received February 25, 1992 Jose Barluenga, *.+ Miguel Alfred0 Ballesteros,t Jian-She Kong,t*s Summary: New 1,3,2diazagermines 2, formed by reac- tion of 4-amino-l-azabutadienes 1 and diethyl- or di- phenylgermanium dichloride, react with dimethyl acety- lenedicarboxylate to yield novel l ,5,2diazagermoclnes 8 in quantitative yield; the crystal structure of 3a has been determined. The behavior of 8 toward hydrolysis and heating is also reported. The chemistry of organosilicon compounds has been widely developed over the last few decades,' and the silicon amides in particular represent very useful species in or- ganic synthesis.2 For instance, we have been able to + Departamento de Qu'unica OrganomeMica. * Permanent address: Department of Chemistry, Nankai Univ- ersity, People's Republic-of China. t Departamento de Quimica Fiaica y Analhica. (1) (a) Colvin, E. W. Silicon in Organic Synthesis; Butterworths: London, 1981. (b) Weber, W. P. Silicon Reagents for Organic Synthesis; Springer: New York, 1983. (c) Colvin, E. W. In Silicon Reagents in Organic Synthesis; Katritzky, A. R., Meth-Cohn, O., Rees, C. W., Eds.; Academic Press: London, 1988. 02~6-7333/92/23~1-23~8~03.00/0 Table I. 1.62-DiazaPermocines 3 Preuared from 1 ~~ ~~ compd" R' R2 R3 R4 Rs mp,OC 3a 4-MeC6H4 Ph Me Ph Et 126-12Bb 3b 4-MeCBH4 Ph Me Ph Ph 16&160b 3c Ph Ph Me c-C8Hl1 Et 125-127b 3d 4-MeC6H4 Ph C1 Ph Et oil 3e c-C6Hl1 H H 4-MeOC6H4 P h c 3f Bu H H 4-MeC6H4 Ph c For isolated compounds 3a-d yields from 1 >95% according to NMR spectra of the crude reaction mixtures. *Recrystallized from hexane-dichloromethane. Not isolated (see text). successfully exploit the reactivity of the nitrogen-silicon bond of 1,3,2-diazasilinestoward esters of acetylenedi- (2) For instance, see: (a) Corriu, R. J. P.; Morenu, J. J. E.; Pataud-Sat, M. J. Org. Chem. 1990,55,2878. (b) Shanzer, A. Angew. Chem., Int. Ed. Engl. 1980,19,327; Angew. Chem. 1980, S2,325. (c) Cninslli, G.; Pan- unzio, M. J. Am. Chem. SOC. 1988,110,6879. (d) Colvin, E. W.; McGarry, D.; Nugent, M. J. Tetrahedron 1988,44,4157. (e) Burnr, 5. A.; Corriu, R. J. P.; Huynh, V.; Moreau, J. J. E. J. Orgonomet. Chem. 1987,333,281. (0 Corriu, R. J. P.; Moreau, J. J. E.; Vemhet, C. Tetrahedron Lett. 1987, 28,2963. 0 1992 American Chemical Society