A STUDY OF CATION ARRAYS IN MB(2), MB(4) AND MB(6) BORIDES .1. THEIR RELATION TO THEIR PARENT METALS

The crystal structure of MB(2), MB(4) and MB(6) borides are analyzed on the basis of their metal arrays. In all of them, the identity of the parent metal can be recognized. Some of the compounds present metal fragments which maintain the topology and shortest M-M distances of the pure metal. In other compounds, these distances are absent but distances to the second and even third nearest neighbors are recognizable. This feature does not seem to depend either on the stoichiometry or the nature of the metal involved. For all the compounds, a geometrical mechanism is proposed, based on the formation of metastable metal structures.