Synthesis and Crystal Structure of Na₇Cu₃O₈, Containing a New Type of Oxocuprate(III) Oligoanion.

Abstract

a New Type of Oxocuprate(III) Oligoanion. -The title compound is prepared by oxidation of a Na3CuO2/NaCuO (2:1) mixture in dry oxygen at 450 °C (Ag crucible, 10 h). Single crystals are grown by annealing of a Na7Cu3O8/Na2O2 (1:1) mixture at 450 °C (argon, Ag crucible, ≈3 months). Na7Cu3O8 crystallizes in the triclinic space group P1 with Z = 1. The prominent structural feature is the new Cu 3 oxocuprate anion which consists of three edge-sharing CuO4 squares. The new trimeric oxocuprate(III) anion supports the expectation that the gap between dimeric and infinite edge-sharing units of square-planar cuprate anions can be closed. -(SOFIN, M.; PETERS, E.-M.; JANSEN*, M.; Z. Anorg. Allg. Chem. 630 (2004) 11, 1547-1549; MPI Festkoerperforsch., D-70569 Stuttgart, Germany; Eng.) -Schramke 48-009 O 7 -8