Alkyl and hydrido derivatives of tetrakis(trimethylphosphine)osmium(II). X-Ray crystal structure of the metallacycle Os[(CH2)2SiMe2](PMe3)4

Abstract

The interaction of the osmium acetato-complexes trans-Os^II(O₂CMe)₂(PMe₃)₄ and Os^III₂Cl₂(µ-O₂CMe)₄ with alkylating agents in the presence of trimethylphosphine has led to the isolation of cis-OsMe₂(PMe₃)₄, Os[(CH₂)₂SiMe₂](PMe₃)₄, OsCl(CH₂PMe₂)(PMe₃)₃, and Os(CH₂C₆H₄)(PMe₃)₄. The hydride cis-OsH₂(PMe₃)₄ has been obtained from K₂[OsO₂(OMe)₄] by interaction with PMe₃ and methanol. The ¹H, ¹³C-{¹H}, and ³¹P-{¹H} n.m.r. spectra of the compounds are discussed. The X-ray crystal structure of the metallacycle Os[(CH₂)₂SiMe₂](PMe₃)₄ has been determined, and the [graphic omitted] ring found to be flat. The Os–C distances are 2.24(1)Å, while the Os–P distances of 2.32 (trans to C) and 2.35 Å(trans to P) indicate the trans influence of the metallacyclobutane is low compared to that of the σ alkyl groups.