A structural investigation of the mercury-sulphur interaction

Bibliography: p. 130-136.The crystal and molecular structures of phenyl, 2-mercaptopyrimidine mercury(II) and phenyl,mercaptobenzene mercury(II) have been determined by the methods of X-ray crystallography. The interaction between mercury and sulphur is investigated. This interaction is of interest both biochemically and toxicologically. More specifically, secondary Hg---S interactions are found to mimic that observed in NMR exchange processes, where they undergo a transition state as a four-membered bridging intermediate. Structural correlations between compounds containing at least one mercury - sulphur covalent bond are examined. The coordination geometry about the mercury atom is generally found to be distorted tetrahedra or octahedra, with a very strong tendency to retain the linear character of the R - Hg - S angle. The electronegativity of sulphur is found to be the most influential parameter in determining the coordination geonetry of the mercury atom. The transition from four- to six-coordinated structures is examined but did not reveal unambiguously whether this occurs by an SN3 or (SN2)2 disubstitution process. The four-membered bridging structure formed by secondary Hg---S interactions is investigated to determine whether minimum energy pathways are evident. However, there is no evidence for pathways representing exchange as observed in solution