Crystal structure and spectroscopic properties of mercury(II) halide complexes. Part 4. Crystal and molecular structure and circular dichroism spectra of the chiral 1 : 1 adduct (S)s(S)c(–)589-methyl 2-phenylbutyl thioether–mercury(II) chloride

Abstract

The crystal and molecular structure of (–)589[(S)s(S)c-Me(EtCHPhCH2)S·HgCl2]2 has been determined by the heavy-atom method from three-dimensional X-ray data collected by counter methods and refined by least-squares techniques to R 0.0468 for 1 207 observed reflections. Crystals are monoclinic, space group P21, with two molecules in a unit cell of dimensions a= 8.457(3), b= 5.634(3), c= 14.667(6)A, and β= 94.68(4)°. The S atom of the donor molecule and the non-bridging Cl(1) atom are strongly bonded to Hg [2.433(4) and 2.315(5)A, respectively]. The overall co-ordination sphere of Hg also includes three crystallographically equivalent bridging Cl(2) atoms [2.677(5), 2.838(10), and 2.995(10)A], and a very weakly π-bonded Ph ring (3.64 A), thus completing an approximately octahedral array. The triply bridging action of Cl(2) leads to the formation of a polymeric structure in which the molecules are linked in chains and further into ribbons parallel to the b axis. l.r. spectroscopic data are consistent with a bent Cl–Hg–Cl moiety. The absolute configuration at both chiral centres of the diastereoisomer is S. The (S)s absolute configuration at the sulphur atom has been correlated with the negative Cotton effect assigned to a charge-trasfer transition at 265 nm in the circular dichroism spectrum. The diastereoselective synthesis of the complex has been confirmed.