[LI(NH3)(4)][SN(SNPH3)(3)]CENTER-DOT-C6H6, CRYSTAL-STRUCTURE OF A STANNIDE WITH TRIGONAL PYRAMIDAL TIN SKELETON

By the reaction of SnPh4 with metallic lithium dissolved in liquid amm onia at 345K for 14d in an autoclave colourless crystals of [Li(NH3)(4 )][Sn(SnPh3)(3)]. C6H6 were obtained besides LiNH2. The crystal struct ure of the tin compound was determined by X-ray methods: triclinic, sp acegroup P (1) over bar, a = 12.305(3) Angstrom, b = 12.421(3) Angstro m, c = 20.448(2) Angstrom, alpha = 78.84(1)degrees, beta = 89.58(1)deg rees, gamma = 73.37(2)degrees and Z = 2. The structure contains [Li(NH 3)(4)](+) cations, [Sn(SnPh3)(3)](-) anions and one benzene molecule. One of the tin atoms (Sn(1)) in the anion has only tin atoms in its fi rst coordination sphere. The resulting tin skeleton can be described b y a trigonal pyramid with distances d(Sn(1)-Sn) = 2.817(1) Angstrom, 2 .833(1) Angstrom and 2.834(2) Angstrom.