Isomerism in Salts and Complexes with Boron Cluster Anions [B10H10]2- and [B20H18]2-

The types of isomerism in compounds with the boron cluster anions [B10H10](2-) and [B20H18](2-) are considered including positional isomerism (found in complexes of boron cluster anions and related to the position of one or two metal atoms around the bulky boron cluster); isomerism of the position of functional groups of substituents in substituted derivatives of the boron cluster anions; isomerism of the boron cage associated with the different structure of the dimeric boron cluster [B20H18](2-); and bond isomerism arising from the realization of various types of metal binding to boron cluster anions in complexes. In addition, examples of isomers of cationic complexes at the outer-sphere position of the boron cluster anion as well as isomerism associated with the denticity of the functional substituent in the boron cluster are shown. The geometry of the boron cluster results in enantiomers crystallizing in compounds. For each type of isomerism, pairs of isomers have been synthesized, the structures of which have been determined by X-ray diffraction of single crystals.