Synthesis, characterisation and study of mercury(II) bromide complexes with triphenylphosphine and heterocyclic thiones. The crystal structures of [bis(triphenylphosphine) dibromo mercury(II)] and [dibromo (pyrimidine-2-thionato) (triphenylphosphine) mercury(II)]. Extended intra-molecular linkages via N-H center dot center dot center dot Br and C-H center dot center dot center dot Br interactions

Fractional crystallisation of the mixture, resulting from the direct reacti on of mercury(IT) bromide with triphenylphosphine (PPh3) and pyrimidine-2-t hione (pmtH), gives crystals of [HgBr2(PPh3)(2)] (1) and [HgBr2(PPh3)(pmtH) ] (2). The complexes have been characterised by their elemental analyses, m elting points and their FT-IR, far-IR, and UV-Vis spectroscopic data. The c rystal structures of both [bis(triphenylphosphine) dibromo mercury(II)] (1) and [dibromo (pyrimidine-2-thionato)(triphenylphosphine) mercury(II)] (2) complexes have been established by single crystal X-ray crystallography at room temperature. Molecule 1 is monomeric with tetrahedral geometry around the metal ion. Two bromide atoms are co-ordinated to the mercury(II) ion [H g(1)- Br(1) = 2.627(2) and Hg(1)-Br(2) = 2.6368(14) Angstrom] while two tri phenylphosphine molecules are also co-ordinated to the metal ion via their phosphorus atoms with Hg(1)-P(1) and Hg(1)-P(2) bond distances of 2.550(4) and 2.491(5) Angstrom. respectively. The complex is covalent in the solid s tate. The unit cell of 2 consists of a molecule with tetrahedral geometry a round the mercury(II) ion. A triphenylphosphine ligand and a pyrimidine-2-t hione molecule are co-ordinated to the metal ion through their phosphorus a nd sulfur atoms with Hg(1)-P(1) and Hg(1) S(2) bond lengths of 2.450(2) and 2.4795(19) respectively. Two bromide atoms are also co-ordinated to the me rcury ion [Hg(1)-Br(1) = 2.7065(10) and Hg(1)-Br(2) 2.6997(II) Angstrom]. T he entire complex is covalent in the solid state. Extended intra-molecular linkages via N-H . . . Br interactions lead to a polymeric structure. Exten ded C-H . . . Br contacts link the alternate parallel chains forming a supr amolecular assembly. (C) 2001 Elsevier Science Ltd. All rights reserved.