SYNTHESIS OF THE NEW ONE-DIMENSIONAL QUATERNARY COMPOUND K2CUTASE4 AND ITS STRUCTURAL RELATIONSHIP TO OTHER COMPOUNDS IN THE K/CU/M/Q (M = NB, TA, Q=S, SE) SYSTEM

The new one-dimensional chain compound K2CuTaSe4 has been synthesized and its structure has been determined by single-crystal X-ray methods. K2CuTaSe4 crystallizes with 8 formula in space group D2h24-Fddd of the orthorhombic system in a cell of dimensions a = 5.735(3), b = 13.481(7), c = 231941(12) angstrom at T = 298 K. The structure, which is of the K2CuNbSe4 type, consists of infinite linear chains separated by K+ cations. These chains am made up of alternating edge-sharing TaSe4 and CuSe4 tetrahedra, which is the basic motif of the M and Cu(I) tetrahedral edge- and comer-sharing networks that are characteristic of other members of the series, including KCu2NbQ4 and K3Cu3M2Q8.