Pyridine-2-thione derivatives of silver(I) and mercury(II): crystal structures of dimeric [bis(diphenylphosphino)methane][(1-oxo-pyridine-2-thionato)silver(I), [2-(benzylsulfanyl)pyridine 1-oxide]dichloromercury(II) and phenyl(pyridine-2-thionato)mercury(II)†

Abstract

Silver(I) complexes, [Ag(O,S-C₅H₄NOS)(L)] [L = Ph₂PCH₂PPh₂ (dppm) 1, Ph₂P(CH₂)₄PPh₂ (dppb) 2, PPh₃ 3 or P(C₆H₄Me-m)₃ 4] were obtained from silver(I) acetate and neutral 1-hydroxypyridine-2-thione(C₅H₅NOS) in water–ethanol medium followed by addition of tertiary phosphines. Direct reaction of mercury(II) halides with 2-benzylsulfanyl)pyridine 1-oxide[C₅H₄NO(SCH₂C₆H₅)] in ethanol formed [HgX₂{C₅H₄NO(SCH₂C₆H₅}] [X = Cl 5 or Br 6]. Similarly, organomercury(II) derivatives, Hg(R)L [R = m-O₂NC₆H₄, L = C₅H₄NS^– 7 or C₅H₄NOS^– 8; R = p-ClC₆H₄, L = C₅H₄NS^– 9 or C₅H₄NOS^– 10; R = C₆H₅, L = C₅H₄NS^– 11 or C₅H₄NOS^– 12] were prepared from Hg(R)(O₂CCH₃) and neutral pyridine-2-thiones(C₅H₅NS or C₅H₅NOS). All these have been characterised using analytical data, IR, far-IR, NMR (¹H, ¹³C or ³¹P) spectroscopy and for 1, 5 and 11 X-ray crystallography. Complex 1 exists as a dimer with dppm bridging the two Ag atoms leading to the formation of an eight membered metallacyclic ring with C₅H₄NOS^– moieties chelating to each Ag atom via O,S-donor atoms. The geometry about each Ag is highly distorted tetrahedral with bond angles varying from 72.85(7) to 137.92(4)°. Compounds 5 and 11 acquire formally dimeric structures via weaker interactions. For example, in 5, Hg binds strongly to one O, two Cl and weakly to one Cl and one S atom of a second ligand molecule. The geometry about each Hg is formally highly distorted trigonal bipyramidal with Cl(1)–Hg–Cl(2) and O(1)–Hg–S(1*) bond angles of 172.84(5) and 151.70(9)° respectively. Finally in 11 Hg is bonded strongly to one C and one S atom, relatively weakly to N{Hg–N 2.795(10), 2.879(9) Å} and very weakly to a second S atom of a second ligand molecule {Hg–S 3.312(3), 3.365(3) Å}. If secondary interactions are ignored the geometry about Hg is formally distorted T-shaped.