KNIPS4 - A NEW THIOPHOSPHATE WITH ONE-DIMENSIONAL AND 2-DIMENSIONAL STRUCTURAL ARRANGEMENTS

Single crystals of a new ternary thiophosphate, KNiPS4, have been synthesized by reaction of the elements in an evacuated silica tube at 873 K for two weeks. The structure was solved in the tetragonal space group P4(2)/mnm with a = 8.2538(4) Angstrom, c = 10.7553(6) Angstrom, and Z = 4. The refinements led to R = 0.0250 (R(W) = 0.0190) for 425 independent reflections and 26 variables. The structure of KNiPS4 consists of nickel in square planar sulfur coordination linked by edge-sharing PS4 tetrahedral groups to produce one-dimensional chains. The chains are aligned in a parallel manner to form layers perpendicular to the c-axis and they are separated by layers of potassium. Tight-binding band structure calculations suggest that the nickel atoms should be in a low-spin Ni-II state resulting in an overall charge balance of (KNiPV)-Ni-I-P-II(S--II)(4). UV-visible spectroscopic measurements indicate KNiPS4 to be semiconducting. (C) 1995 Academic Press, Inc.