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Interaction of methylmercury(II) with the bifunctional ligand o-diphenylphosphinobenzoate, dpb. Synthesis and characterization of [(dpb)HgMe] and [(dpbo)HgMe], dpbo=o-diphenylphosphinoxidebenzoate

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Abstract The complex [(dpb)HgMe] (1) is obtained by reaction of MeHg(OH) with o-diphenylphosphinobenzoic acid (Hdpb); alternatively the solvate [(dpb)HgMe] · 0.5H2O · 0.5C5H5N (1bis) can be prepared by reacting MeHgCl with Hdpb and pyridine. The derivative [(dpbo)HgMe] (2), where dpbo is o-diphenylphosphinoxidebenzoate, is formed by reaction of 1 or 1bis solutions with atmospheric oxygen. Crystal data for 1bis: monoclinic, space group P2/n, a=10.413(4), b=9.831(3), c=20.674(3) A, β=102.51(3)°, Z=2. Crystal data for 2: triclinic, space group P1, a=11.535(2), b=12.897(5), c=13.275(7) A, α=88.31(4), β=73.65(4), γ=85.27(4)°, Z=2. In 1bis the mercury atom displays a distorted linear fashion, being coordinated to a methyl group and to the phosphorus atom of the dpb ligand. Two additional weaker linkages cause the packing in pairs of the molecules. In 2 the mercury is linearly linked to a methyl group and to an oxygen atom of the carboxylic group of the dpbo ligand. Also in this case the coordination around the mercury center is completed by two weaker additional bond interactions, which, involving the oxygen atoms of the adiacent moiety, determine the dimerization of the molecule. The multinuclear magnetic resonance spectra of 1 (or 1bis) which have been compared with those of the related complex [(PPh3)HgMe](CF3SO3) (3) and of the solution containing 1 and CF3SO3H (molar ratio 1:1.5), do not seem to unambigously support a dimeric configuration of the complex in solution.