A coordination chemistry approach towards ternary M/14/16 anions

The synthesis and exploration of heterobimetallic chalcogenide compounds has been studied intensely during the last decade. Besides the general interest in the exploration of novel synthetic pathways and the structural attraction of the target compounds, today's research activity concentrates on the development of novel materials. Ternary chalcogenides as well as their molecular, nanostructured or mesostructured derivatives can be formally viewed as combinations of binary chalcogenometallates; accordingly, they provide combinations or mixtures of the specific properties, e.g. opto-electronics or magnetism of the formally underlying parent compounds. Despite the fact that many tetrel chalcogenides exhibit (photo-)semiconducting properties, only few reports were available on ternary M/14/16 aggregates; moreover, since the known M/14/16 complexes were usually generated from separate sources of the three components, it was practically impossible to design the size or structure of the 14/16 fragment which would control the spatial separation of the transition metal atoms. As an efficient alternative, we have developed a coordination chemical route by using a preformed binary 14/16 source: by reactions of ortho-chalcogenotetrelate anions [E′E4]4− under ambient conditions in solution, we gain systematic access to complexes with definite, close proximity of the transition metal centers—allowing for interaction of the latter within the heterobimetallic molecular anions and anionic networks. This review will focus on synthesis, structures and physical properties of the resulting quaternary compounds with M/14/16 anions.