ChemInform Abstract: Magic Electron Counts for Networks of Condensed Clusters: Vertex-Sharing Aluminum Octahedra.
Abstract
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ChemInform Abstract
The Al substructure of the M1M12Al9 (M1: Ba, M2: Fe, Co, Ni; M1: Sr, M2: Co, Ni; M1:Ca, M2: Co) and CaNiAl9 compounds is a three-dimensional network of vertex-sharing Al octahedra. Bonding is analyzed at the extended Hueckel level. It is found that the number of skeletal electrons per Al cluster optimal for Al—Al bonding is reduced from 14 for an isolated cluster to 12 for the cluster dimer and cluster chain, 10 for the two-dimensional cluster sheet, and 8 for the cubic network in which all cluster vertices are shared. In the systems M1M22Al9, the Fermi level lies near a gaplike dip in the DOS curve and separates the Al—Al bonding states from the Al—Al antibonding ones.
