Chemistry of the metal carbonyls. Part LX. Halogeno(organo-group IVB) carbonyls of ruthenium and osmium

Abstract

Bromine or iodine react with the complexes [(Me₃Si)Ru(CO)₄]₂, [(Me₃Ge)Ru(CO)₄]₂, and [(Me₃Si)Os(CO)₄]₂ in hexane to form compounds trans-[(Me₃M)M′(CO)₄X](M = Si or Ge; M′= Ru or Os; X = Br or I). Several of these complexes, and the corresponding tin compounds, can also be obtained by selective halogen cleavage of the Group IVB–transition-metal bonds in the compounds [(Me₃M)₂M′(CO)₄]. The monohalides [(Me₃M)M′-(CO)₄X] readily lose carbon monoxide to afford halogen-bridged complexes [(Me₃M)M′(CO)₃X]₂. I.r. and ¹H n.m.r. spectroscopy indicate that these complexes exist as isomeric mixtures. Triphenylphosphine cleaves the halogen bridges of the dimeric species to give stable compounds [(Me₃M)M′(CO)₃(PPh₃)X], which are less well prepared directly from [(Me₃M)M′(CO)₄X]. The hydrides [(Me₃M)Ru(CO)₃(PPh₃)H](M = Si or Sn) have been obtained by sodium borohydride reduction of the iodides. The carbonyl [(Me₃Si)Ru(CO)₄Re(CO)₅] is described.