Decamethylsilicocene chemistry: Reaction with carbon-nitrogen triple-bond species

Reaction of decamethylsilioocene, (Me(5)C(5))(2)Si (1), with MeSCN, 2,4-Me(2)C(6)H(3)OCN, Me(2)-NCN, BrCN, and Me(3)SiCN is described. In all reactions, the formal oxidation state of the silicon atom changes from -2 in 1 to +4 In the products, and the hapticity of the pentamethylcyclopentadienyl ligands changes from eta(5) to eta(1). Under mild conditions (-78 degrees C or room temperature) 1 reacts with 2 equiv of MeSCN, 2,4-Me(2)C(6)H(3)OCN, and Me(2)NCN under C-C bond formation to the respective diazasilole derivatives 3-5. Reaction of 1 with BrCN at -78 degrees C affords the silyl cyanide 7; at room temperature, a mixture of the silyl cyanide 7 and of the silyl isocyanide 8 is formed. Reaction of 1 with Me(3)SiCN leads to the silyl cyanide 10. In the reactions described, the product formation presumably proceeds via [2 + 1] cycloaddition compounds of the azasilirene type as reactive intermediates. All products are characterized by NMR (H-1, C-13, Si-29) spectroscopy, IR spectroscopy, mass spectrometry, and microanalytical data. The structures of 3, 4, and 10 were determined by X-ray crystallography.