SYNTHESIS AND CRYSTAL-STRUCTURE DETERMINATION OF NA-2[SN(NH2)(6)] ANDNA-2[SN(ND2)(6)] BY X-RAY AND NEUTRON-DIFFRACTION

Na-2[Sn(NH2)(6)] was obtained by the reaction of (C6H5)(4)Sn and NaNH2 in NH3 as solvent at 345 K in a stainless steel autoclave. Colourless crystals with the shape of flat, hexagonal prisms were isolated and e xamined by X-ray methods. The structure was solved in the spacegroup R (3) over bar with Z = 3, including all hydrogen positions. Na-2[Sn(NH 2)(6)]:R (3) over bar, a = 5.982(1)Angstrom, c = 18.405(6)Angstrom, Z = 3, AgKa, N(var.) = 23, (F-0(2)) > 3 sigma(F-0(2)) = 640, R/R-w(w = 1 ) = 0.025/0.029 The structure of Na-2[Sn(NH2)(6)] is isotypic with tha t of K-2[Sn(NH2)(6)]. It can be described as a cubic close packing of isolated units [Sn(NH2)(6)](2-) with all tetrahedral voids occupied by sodium. To confirm the hydrogen positions found by X-ray measurements , Na-2[Sn(ND2)(6)] was examined by neutron powder diffraction. Na-2[Sn (ND2)(6)]:R (3) over bar, a = 5.9803(1)Angstrom, c = 18.4006(3)Angstro m, Z = 3, R-P/R-Bragg = 0.018/0.061, N(var.) = 27 The H positions dete rmined by the X-ray measurements are in good agreement with the result s obtained from the neutron data.