infinity(1)[Sn-3/3] tubes and AuSn3 building units: Synthesis and crystal structure of Na2AuSn3

Silver coloured, brittle single crystals of the metallic conducting compoun d Na2AuSn3 were synthesized by reaction of sodium azide with gold sponge an d tin powder at T = 820 K. The structure of the new compound (space group P 6(3)/mmc, Z = 4, a = 9.585(1) Angstrom, c = 7.516(2) Angstrom) was determin ed from X-ray single-crystal diffractometry data. Na2AuSn3 crystallizes in a ternary variant (Lu2CoGa3 type) of the AlB2 type. The tin atoms form the motif of a (1)(infinity)[Sn-3/3] tubular fragment of the hexagonal diamond structure. The (1)(infinity)[Sn-3/3] tubes are connected to a framework str ucture via gold atoms with a trigonal planar tin coordination. The sodium a toms are placed in channel-like cavities of the Au-Sn partial structure.