Complexes of methylmercury(II) with dithiol ligands: spectroscopic and crystallographic studies. The crystal structure of trans-1,2-dimercaptocyclohexanebis[methylmercury(II)], [Hg2Me2(S2C6H10)]

Abstract

Bis[methylmercury(II)] complexes have been prepared with the potentially bidentate dithiol ligands trans-1,2-dimercaptocyclohexane (1), 3,4-dimercaptotoluene (2), and endo,cis-2,3-dimercaptobicyclo[2.2.1]heptane (3). The crystal structure of [Hg₂Me₂L][L =(1)] has been determined by X-ray diffraction. The crystals are monoclinic, space group P2₁/c, with a= 9.609(3), b= 13.428(3), c= 10.268(3), β= 112.87(2)°, and Z= 4. A total of 1 794 intensities with l/σ(l) 3.0 were recorded at 123 K with a four-circle diffractometer and the structure refined by the least-squares method to yield a final R value of 0.037. One Hg^IIMe group is bound to one of the sulphur atoms [Hg(2)–S(2) 2.363(4)Å] with a nearly linear S(2)–Hg(2)–C(2) bond angle [177.1(5)°], whereas the second Hg^IIMe co-ordinates strongly to the other sulphur atom [Hg(1)–S(1) 2.367(4)Å] but forms a weaker bond with the first sulphur atom [Hg(1)–S(2) 2.857(3)Å] and a significantly bent S(1)–Hg(1)–C(1) bond angle [167.8(5)°]. Spectroscopic studies in solution indicate a similar type of bonding in the complexes formed by (1), (2), and (3).