Synthesis and Structures of Heteroleptic Silylenes

The reaction of benzamidinato silicon trichloride [{PhC(NR)2}SiCl3] [R = But (1), SiMe3 (2)] with 2 equiv of potassium in THF afforded mononuclear chlorosilylene [{PhC(NBut)2}SiCl] (3) and [{PhC(NSiMe3)2}2SiCl2] (4), respectively. Compound 4 was formed by the disproportionation of unstable [{PhC(NSiMe3)2}SiCl]. The reaction of [{PhC(NBut)2}SiCl3] (1) with 1 equiv of LiR (R = NMe2, OBut, OPri, PPri2) in THF yielded [{PhC(NBut)2}SiCl2R] [R = NMe2 (5), OBut (6), OPri (7), PPri2 (8)]. Treatment of 5−8 with 2 equiv of potassium in THF resulted in the novel heteroleptic silylene [{PhC(NBut)2}SiR] [R = NMe2 (9), OBut (10), OPri (11), PPri2 (12)]. Compounds 4, 9, and 12 have been analyzed by X-ray crystallography.