Trimethylphosphite derivatives of the mixed cobalt—iridium tetranuclear cluster Co2Ir2(CO)12

Up to four carbonyl groups of Co₂Ir₂(CO)₁₂ have been replaced by trimethylphosphite to form tetranuclear clusters of formula Co₂Ir₂(CO)_12?nP(OMe)₃]_n. The clusters do not exhibit the redistribution of the metal core which is observed in the case of mixed cobalt—rhodium clusters. Attachment of three or four trimethylphosphites to the metal skeleton of the cluster inhibits the scrambling of the carbonyl groups.