On a lead nickel manganese tellurium oxide PbMn2Ni6Te3O18 containing Mn2+ in trigonal prismatic oxygen coordination

A new lead manganese nickel tellurium oxide PbMn2Ni6Te3O18 is light green i n color and crystallizes in hexagonal symmetry, space group C-6h(2), P6(3)/ m (no. 176), with cell parameters a = 9.294(1), c = 8.823(1) Angstrom, and Z = 2. The structure was determined from a single crystal X-ray study and r efined to the conventional values R = 0.026 and wR(F-2) = 0.046. Ni2+ and T e6+ show octahedral and Mn2+ shows trigonal prismatic coordination by O2-. The crystal structure is featured by a (2)(infinity)[Ni6Te3O18](6-) network together with two kinds of channels along [001] with trigonal and hexagona l shape. Isolated face shared [Mn2O9](14-) trigonal prismatic polyhedra dou bles are located in the trigonal channels, while one-dimensional infinite c hains of [PbO6+6](22-) oxygen cube dodecahedra are incorporated in the hexa gonal channels, (C) 2000 Elsevier Science Ltd.