BETA-DICOBALT PYROPHOSPHATE

A new high-temperature or beta form of dicobalt diphosphate, Co2P2O7, has been isolated in space group A2/m (non-standard setting of C2/m). As in other high-temperature forms of transition-metal pyrophosphates, metal atoms lie on planes in a two-dimensional hexagonal array [Co-Co distances 3.461 (4) and 3.284 (3) angstrom] with adjacent metal atoms linked by two O-atom bridges. Co atoms are octahedrally coordinated w ith axial distortions [average Co-O(eq) 2.14 (1), Co-O(ax) 2.32 (1) an gstrom]. The pyrophosphate groups lie along planes between metallic la yers.