Ge₃₂Co_9−x: Creating “Empty” Space by High Pressure

Abstract

The compound Ge 32 Co 9À x (x = 0.54(6), a = 10.9861(3) Å, space group Im3 ̄m) prepared under high pressure and at high temperature is metastable under ambient conditions. It crystallizes in a new structure type, Pearson symbol cI82À 1.08. The crystal structure represents a slightly distorted cubic primitive arrangement of germanium atoms with part of the Ge cubes filled by cobalt. Analysis of the chemical bonding by real-space methods revealed threecore cluster units Ge 16 Co 3 and seemingly empty regions comprising either covalent inter-polyhedral GeÀ Ge bonds or lone-pairs located at the germanium atoms. The electrical conductivity is metal-like.