Triosmium clusters containing the ligands CNH2, NCHCN, and NCMeCN derived from cyanide ion, cyanogen, and acetonitrile

Abstract

The addition of cyanide ion to [Os3H2(CO)10] gives [Os3H2(CN)(CO)10]– as four isomers in solution. Subsequent protonation at nitrogen leads via intermediates to the aminomethylidyne complex [Os3H(µ-CNH2)(CO)10], the characterisation of which was assisted by the synthesis of the corresponding 13CNH2, C15NH2, and deuteriated analogues. Hydrogen exchange at the CNH2 ligand is slow in neutral solution but is both acid- and base-catalysed. Rather than displacing acetonitrile from [Os3H(CO)10(MeCN)(PMe2Ph)]PF6, cyanide ion adds at MeCN to give two main isomers of [Os3H (NCMeCN)(CO)9(PMe2Ph)]. Related complexes [Os3H(NCHCN)(CO)9L](L = CO or PMe2Ph) were obtained by reaction of [Os3H2(CO)9L] with cyanogen (C2N2) at room temperature. Rotation about the CN bonds in the iminyl complexes is sufficiently slow to allow the separation of isomers when L = PMe2Ph. The isomeric form [Os3H(NHCCN)(CO)10] was also obtained.