The first metal carbonyl clusters, Fe(CO), Ir(CO), and Rh(CO), were reported starting in the 1930s, often by Walter Hieber. The structures were subsequently established by X-ray crystallography.
Paolo Chini (1928–1980) was a pioneer for the synthesis and characterization of high-nuclearity metal carbonyl clusters. His first studies started in 1958, in the attempt to repeat a patent that claimed an improved selectivity in hydroformylation. From a mixture of iron and cobalt carbonyls the first bimetallic carbonyl cluster HFeCo(CO) was obtained.