Rare earth metal borocarbides - Examples of coordination compounds in solid-state chemistry

A variety of structural types of solid-state rare earth metal borocarbide materials containing infinite two-dimensional layers, infinite one-dimensional chains, or finite groups of boron and carbon are reviewed. Although the solid-state language of Zintl-Klemm concept, band structures, and density of states is necessary to rationalize this kind of compound, they are governed by the laws that guide most molecular and solid-state structural chemistry: the relationship between the electron count and the structural arrangement. More precisely, one could think of these materials as solid-state coordination compounds in which the classical bonding scheme of sigma-donation, sometimes supplemented by some pi-backdonation, is present. (C) 1998 Elsevier Science S.A. All rights reserved.