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Protodemetallation of pyridinephenylmercury(II) compounds by diphenyldithiophosphinic acid. The molecular and crystal structure of [Hg2(S2PPh2)4]

1997; Elsevier BV; Volume: 256; Issue: 2 Linguagem: Inglês

10.1016/s0020-1693(96)05442-4

1873-3255

José S. Casas, M.S. Garcı́a-Tasende, A. Sánchez, J. Sordo, E.M. Vázquez-López,

Metal complexes synthesis and properties

The reactions of [2-pyridin-2′-yl)-phenyl]mercury(II) acetate [Hg(PhPy)(OAc)] and [2-(pyridin-2′-yl)-phenyl]mercury(II) diphenyldithiophosphinate [Hg(PhPy)(S2PPh2)] with diphenyldithiophosphinic acid in chloroform at room temperature both led to the cleavage of the CHg bond, giving phenylpyridine and [Hg2(S2PPh2)4]. The [Hg(PhPy)(S2PPh2] reaction was monitored by 1H NMR spectroscopy. Although the process went smoothly at the beginning, the protodemetallation reaction slowed as more acid was added. A hypothesis is put forward as to the cause of this loss of effectiveness as protodemetallation progresses. The crystal structure of [Hg2(S2PPh2)4] was solved by X-ray diffraction. This compound crystallizes in the triclinic space group P1 (No. 2) with a=9.150(3), b=10.560(4), c=13.715(5) Å, α=93.46(2), β=102.44(2), γ=105.34(2)°, Z=1. Its structure comprises centrosymmetric dimers, each forming an eight-membered ring in a twisted chair conformation. Each mercury atom is coordinated to one chelating and two bridging ligands, giving rise to a distorted tetrahedral arrangement around the metal, with two short HgS bonds of 2.428(2) and 2.467(2) Å and two long ones of 2.678(2) and 2.761(2) Å. Each Hg is also involved in a 3.338 Å long secondary bond across the eight-membered ring. IR, Raman and 1H, 31P and 199Hg NMR data for [Hg(PhPy)(S2PPh2)] and [Hg2(S2PPh2)4] are also discussed.