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)Å, 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)Å, 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)Å], and a very weakly π-bonded Ph ring (3.64 Å), 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.