Condensed [PtIn3/3] and [PtIn6/6] Units as Structural Motifs in ScPtln, TbPtln, and HoPtln

Abstract

The ternary indides ScPtln, TbPtln, and HoPtln were synthesized by reaction of the elements in an arc-melting furnace and subsequent annealing for four weeks. ScPtln and HoPtln are reported here for the first time. The three indides crystallize with the hexagonal ZrNiAl structure, a ternary ordered version of the Fe2P type, space group P6̄2m. Single crystal X-ray data yielded a = 754.6(1), c = 348.31(8) pm, wR2 = 0.0390, 177 F2 values for ScPtln, a = 759.3(1), c = 387.6(1) pm, wR2 = 0.0576, 183 F2 values for TbPtln, and a = 758.13(1), c = 381.62(1) pm, wR2 = 0.0530, 239 F2 values for HoPtln with 14 variable parameters for each refinement. Striking structural motifs of these intermetallics are short Pt-In distances (270 - 286 pm) within the three-dimensional [Ptln] polyanions which are composed of Pt(2)In6 trigonal prisms and trigonal planar P t(l)In3 units. The platinum-indium substructure of ScPtln is discussed in comparison with the various platinum-indium networks in the structures of Ptln2, Pt3In7, SrPtln, Sr2Pt3ln4, SrPtIn2, LaPtIn3, and PtIn7Fi3.