Synthesis and crystal structure determination of three layered-type thiophosphate compounds KMP2S73 (M = Cr, V, In)

Three new thiophosphates KMP2S7 (M = Cr, V and In) have been synthesized an d their structure determined from twinned crystals through X-ray diffractio n experiments. The three compounds crystallize in the monoclinic system, sp ace group C2 and Z = 2, with the following lattice parameters: KCrP2S7, a = 8.5146(6), b = 9.5848(6), c = 6.3052(5) Angstrom, beta = 97.981(8)degrees V = 509.59(8) Angstrom (3); KInP2S7, a = 8.7506(9), b = 9.9685(9), c = 6.31 51(8) Angstrom, beta = 98.906(13)degrees, V = 544.2(2) Angstrom (3); KVP2S7 , a = 8.5553(6), b = 9.5765(5), c = 6.3323(4) Angstrom, beta = 98.630(8)deg rees V = 512.8(1) Angstrom (3). For each compound, the structure determinat ion was carried out taking into account the two twin domain sets (rejecting only the partially overlapping reflections) down to R = 3.08%, R = 3.20%, and R = 3.08% (2 sigma level) for KCrP2S7, KInP2S7, and KVP2S7, respectivel y. The two-dimensional structures, built from bitetrahedral [P2S7] units sh aring edges and corners with [MS6] octahedra, are isotypic to the structure of RbVP2S7, with the same nonharmonic behavior of the alkali metal. (C) 20 00 Elsevier Science Ltd. All rights reserved.