A New Type of Copper Oxide Cluster in the Crystal Structure of NaCu12(Si2O7)4Cl, a New Representative of the Alkali Copper Disilicate Family

Abstract

A new compound NaCu₁₂(Si₂O₇)₄Cl was synthesized by chemical vapor deposition. Using X-ray diffraction analysis, its crystal structure was established as containing 0-dimensional copper oxide clusters Cu₁₂O₂₄ of a new type, which can be described as a truncated tetragonal bipyramid built from CuO₄ square groups, connected by sharing common edges and vertices. The complexes are combined through Si₂O₇ disilicate groups into a three-dimensional electroneutral framework [Cu₁₂(Si₂O₇)₄]⁰, built on the principle of the bcc grid (body-centered cubic lattice). Disordered Na⁺ and Cl^– ions are located in the cavities of the framework. The structure of the 12-nucleated copper oxide clusters is similar to those of the Cu_nO_2n polyoxocuprates found in various minerals and inorganic compounds.