Synthesis, structure and spectral properties of [(HgPh)(2)TbSMe]; A dinuclear 2-S-methylthiobarbiturate of phenylmercury(II) exhibiting linkage isomerism

The reaction of 2-S-methylthiobarbituric acid (H(2)TbSMe) with phenylmercury(II) acetate in ethanol afforded the title complex, which crystallizes in the space group P2(1)/c (No. 14). The asymmetric unit consists of two independent [(HgPh)(2)TbSMe] molecules: in molecule 1, the two organometallic moieties are bound primarily to the nitrogen atoms of the ligand ring (N(1) and N(3)); in molecule 2, one phenylmercury(lI) is N(1)-bound but the other is bound to the exocyclic oxygen contiguous to N(3). Hence molecules 1 and 2 are linkage isomers. Several weak intra- and intermolecular interactions are also observed. In DMSO solution, H-1, C-13 and Hg-199 NMR measurements suggest fast exchange of phenylmercury(II) between N- and O-coordination, with prevalence of the former.