SYNTHESIS AND CHARACTERIZATION OF HG(II) COMPLEXES OF ME3MCH2SEME, (M = SI, GE) - CRYSTAL-STRUCTURES OF [HGX2(ME3SICH2SEME)]2, X = CL, BR, I

Complexes of the general formula [HgX2(Me3MCH2SeMe)]2, where M = Si, Ge; X = Cl, Br, I, have been prepared and characterized by 1H nuclear magnetic resonance and Raman spectroscopy. Crystal structures of [H8X2(Me3SiCH2SeMe)]2, where X CI, Br, and 1(1, 2, and 3 respectively), show that they have centrosymmetric dinuclear strnctures. The crystals of 1 and 2 are monoclinic, while those of 3 are triclinic. For 1: P21/c, a 14.235(11). b = 6.551(6), c = 14.211(9) Å, β I 17.33(5)°, Z 2, and R = 0.0560. For 2: P21/c, a 14.329(6), b = 6.695(2), c 14.819(4) Å, β=118.47(2)', Z = 2, and R 0.0540. For 3: P1, a = 7.651(2), b = 8.387(2), c = 12.321(4) Å α = 90.07(2), 13 = 91.80(2), γ = 116.02(2)°, Z 1, and R 0.0565. All three complexes show the expected pseudotetrahedral geometry about mercury. The stereo- chemical differences arise in the arrangement of the bulky trimethylsilylmethyl groups, which in the HgI2 adduct are rotated away from the centre of the molecule but which in the HgCI2 and HgBr2 adducts are turned towards the centre. These are the first dinuclear structures reported of HgBr2 and HgI2 adducts since it was demonstrated 46 years ago by Evans et at. that [HgBr2(AsBu3)12 was present in [HgBr2(AsBu3)2HgBr2].