Condensed [PtIn3/3] and [PtIn6/6] units as structural motifs in ScPtIn, TbPtIn, and HoPtIn

The ternary indides ScPtIn, TbPtIn, and HoPtIn were synthesized by reaction of the elements in an are-melting furnace and subsequent annealing for fou r weeks. ScPtIn and HoPtIn 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 P (6) over bar 2m. Single crystal X-r ay data yielded a = 754.6(1), c = 348.31(8) pm, wR2 = 0.0390, 177 F-2 value s for ScPtIn, a = 759.3(1), c = 387.6(1) pm, wR2 = 0.0576, 183 F-2 values f or TbPtIn, and a = 758.13(1), c = 381.62(1) pm, wR2 = 0.0530, 239 F-2 value s for HoPtIn with 14 variable parameters for each refinement. Striking stru ctural motifs of these intermetallics are short Pt-In distances (270 - 286 pm) within the three-dimensional [PtIn] polyanions which are composed of Pt (2)Ins trigonal prisms and trigonal planar Pt(1)In-3 units. The platinum-in dium substructure of ScPtIn is discussed in comparison with the various pla tinum-indium networks in the structures of PtIn2, Pt(3)nn(7), SrPtIn, Sr2Pt 3In4, SrPtIn2, LaPtIn3, and PtIn7F13.