New Compounds with [As7]3– Clusters: Synthesis and Crystal Structures of the Zintl Phases Cs2NaAs7, Cs4ZnAs14 and Cs4CdAs14

Abstract

Three new cluster compounds, Cs2NaAs7, Cs4ZnAs14, and Cs4CdAs14 were obtained from high temperature reactions. Their structures feature heptaarsenide [As7]3– anions, where the clusters in Cs4ZnAs14 and Cs4CdAs14 are dimerized by the linkers Zn and Cd, respectively. The bonding characteristics of these clusters are discussed and compared. Band structure calculation on Cs2NaAs7 suggests that this compound is a semiconductor with an energy gap of circa 1.6 eV, which is in consistent with the dark red color of the crystals.