Protodemetallation of pyridinephenylmercury(II) compounds by diphenyldithiophosphinic acid. The molecular and crystal structure of [Hg 2(S 2PPh 2) 4]

• Published in: Inorganica Chimica Acta Vol. 256; no. 2; pp. 211 - 216
• Main Authors: Casas, J.S., García-Tasende, M.S., Sánchez, A., Sordo, J., Vázquez-López, E.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.03.1997
• Subjects: Crystal structures; Dithiophosphinate complexes; Mercury complexes; Protodemetallation; Crystal structures; Mercury complexes; Protodemetallation; Dithiophosphinate complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(96)05442-4

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)(S 2PPh 2)] with diphenyldithiophosphinic acid in chloroform at room temperature both led to the cleavage of the CHg bond, giving phenylpyridine and [Hg 2(S 2PPh 2) 4]. The [Hg(PhPy)(S 2PPh 2] 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 [Hg 2(S 2PPh 2) 4] was solved by X-ray diffraction. This compound crystallizes in the triclinic space group P 1 (No. 2) with a=9.150(3), b=10.560(4), c=13.715(5) A ̊ , 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)(S 2PPh 2)] and [Hg 2(S 2PPh 2) 4] are also discussed.