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

The interaction of the osmium acetato-complexes trans-OsII(O2CMe)2(PMe3)4 and OsIII2Cl2(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)A, while the Os–P distances of 2.32 (trans to C) and 2.35 A(trans to P) indicate the trans influence of the metallacyclobutane is low compared to that of the σ alkyl groups.