Preparation of [(mes)Os(CNR)Cl2] and reactions of the methyl isocyanide complex with organolithium and Grignard reagents. X-ray crystal structure of [(mes)Os(=C(NHCH3)C6H5)(C6H 5)2]

Article abstract of DOI:10.1021/om00055a053

The isocyanide complexes [(mes)Os(CNR)Cl₂] (2-4) are prepared almost quantitatively from [(mes)OsCl₂]_n (1) and CNR in dichloromethane. Reactions of 2 (R = CH₃) with CH₃Li and C₆H₅Li in hydrocarbon-ether give the dimethyl and diphenyl derivates [(mes)OsR₂(CNCH₃)] (5, 6) in excellent yields. Treatment of 2 with CH₃MgI leads to the formation of a mixture of [(mes)OsCH₃(CNCH₃)I] (7) and [(mes)Os(CNCH₃)I₂] (9), which can be separated by column chromatography. Analogously, from 2 and C₆H₅MgI, both [(mes)OsC₆H₅(CNCH₃)I] (8) and 9 have been obtained. In contrast, reaction of 2 with C₆H₅MgBr gives, besides [(mes)OsC₆H₅(CNCH₃)Br] (11), the carbene complex [(mes)Os(=C(NHCH₃)C₆H₅)(C₆H ₅)₂] (10) as the main product. The X-ray crystal structure of 10 has been determined (monoclinic space group P2₁/n with a = 12.402 (3) ?, b = 14.237 (2) ?, c = 13.622 (2) ?, β = 91.54 (1)°). The molecule possesses a piano-stool configuration with an Os-C(carbene) distance of 1.992 (5) ?.