Unique Approach to Copper(I) Silylene Chalcogenone Complexes

Silylene-S-thione [PhC(NtBu)(2)Si(-S)N(SiMe3)(2)] (2) and silylene-Se-selone [PhC(NtBu)(2)Si(-Se)N(SiMe3)(2)] (3) compounds were prepared from the silylene [PhC(NtBu)(2)SiN(SiMe3)(2)] (1) with 1 equiv of 1/8 S-8 and 1 equiv of Se powder, respectively, in high yields. Furthermore, compounds 2 and 3 reacted with CuCl and CuBr and yielded [{PhC(NtBu)(2)}Si(=S -> CuX)N(SiMe3)(2)] (X = Cl (4), Br (5)) and [{PhC(NtBu)(2)}Si(=Se -> CuX)N(SiMe3)(2)] (X = Cl (6), Br (7)), respectively. Complexes 47 can also be obtained from the direct reaction of sulfur and selenium with the corresponding silylene copper complexes [{PhC(NtBu)(2)}Si-{N(SiMe3)(2)}](2)Cu2X2 (X = Cl (8), Br (9)). The latter route avoids the preparation of the highly reactive silylene chalcogenones. For comparison purposes the silylene PhC(NtBu)(2)SiN(SiMe3)(2) in 2 and 3 was replaced by NHC (1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene) (10). The resulting products NHC=S (thione 11) and NHC=Se (selenone 12) react with CuBr and lead to the expected complexes (NHC=S -> CuBr) (13) and (NHC=Se -> CuBr) (14). However, unlike silylene complexes, 13 and 14 cannot be prepared by reacting NHC-CuBr (15) with chalcogens.