Journal Archive

Platinum Metals Rev., 1969, 13, (1), 22

Osmium Complexes Containing Four Metal Atoms

The preparation of interesting new complexes containing four metal atoms has been reported by C. W. Bradford, of the Johnson Matthey Research Laboratories, working under the guidance of Professor Sir Ronald Nyholm (Chem. Comm., 1968, 867). These are obtained by reacting osmium carbonyl, Os3(CO)12, with triphenylphosphine gold halides. It appears that only one of the three Os-Os bonds in the original triangular cluster is broken and this gives rise to what is possibly the first case of a linear arrangement of four covalent bonded metal atoms:

This new compound is red in colour, mono-meric and a non-conductor in solution, and has an infra-red spectrum in the C-O stretching region which is consistent with a linear arrangement of the Au-Os-Os-Os moiety.

The corresponding bromo-compound:

has also been isolated and has properties similar to those of the chloride.

If X-ray crystallographic studies at present being made show that a linear arrangement is indeed present, then it is interesting to speculate on the possibility of synthesising from these compounds other compounds containing even longer chains of metal atoms.

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