Cluster Complexes of Cobalt

The word cluster in this section will refer to complexes of cobalt containing three or more metals for which there is, moreover, evidence for the existence of metal-metal bonds in the complex. In addition, for such compounds to be reported in this section, the otganometallic nature of the cluster (the direct interaction between one of the cobalt atoms and at least one carbon atom) must be present. In fact, purely inorganic cobalt clusters became more numerous until recently. Some examples will be described at the end of this section however, these compounds will not be coveted in any comprehensive fashion. Polynuclear clusters, which contain other metal atoms associated to cobalt, are the subjects of another chapter of this work. 

The amount of work devoted to cobalt clusters seems to have dramatically decreased since COMC (1995) has appeared. Indeed, whereas in the previous report cobalt clusters were a wealthy research field, the number of research articles dealing with either new synthetic work involving Co clusters or various applications of these complexes has decreased significantly during the last decade. In fact, there have been relatively few reports of new types of cobalt clusters as compared to the previous period covered in COMC (1995). Most of what was achieved concerned reactions on already-described basic structures. 

Some specific aspects of the cluster chemistry involving cobalt atoms have been reviewed.  

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Within this context, the present article concentrates on transition metal cluster complexes of cobalt, iron and manganese with mixed chalcogen/carbonyl ligand spheres obtained by reaction of simple binary metal carbonyls with alkali-metal sulfides, alkali-metal thiolates or transition-metal thiolate complexes and their selenium or tellurium counterparts. 

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