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

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.