Reactivity of [NBu4]2[{(C6X5) 2M(μ-OH)}2] (X = F or Cl; M = Pd or Pt) towards heterocyclic thiones: Crystal structure of [NBu4]2[{(C6F5) 2Pd(μ-η2-LL′)}2] (LL′ = methylimidazole-2-thiolate)

Article abstract of DOI:10.1016/s0020-1693(98)00164-9

The di-μ-hydroxo complexes [NBu₄]₂[{(C₆X₅) ₂M(μ-OH)₂}₂] (M = Pd or Pt; X = F or Cl) react with heterocyclic thiones H(LL′) (1:2 molar ratio) to give the heterocyclic-2-thiolate complexes [NBu₄] [(C₆X₅)₂M(η²-LL′)] (LL′ = pyridine-2-thiolate (pyS), pyrimidine-2-thiolate (pyrimS), 2,6-dimethyl-5-oxo-1,2,4-triazine-3-thiolate (Me₂tazS), 6-methyl-5-oxo-1,2,4-triazine-3-thiolate (MetazS)) or [NBu₄]²[{(C₆F₅) ₂M(μ-η²-MeimidS)}₂] (MeimidS=methylimidazole-2-thiolate). The variable-temperature ¹H NMR spectra of the complexes [NBu₄] [(C₆X₅)₂M(η₂-LL′)] over the range - 50 to +60°C are all static, but those of the methylimidazole-2-thiolate complexes [NBu₄]₂[{(C₆F₅) ₂M(μ-η²-MeimidS)}₂] (M=Pd and Pt) suggest the existence of dynamic chemical processes involving both dimeric and monomeric species. Crystallization of [NBu₄]₂[{(C₆F₅)₂Pd} ₂( (μ-η²-MeimidS)}₂] from wet dichloromethane-hexane-ether afforded the mixed complex [NBu₄]₂[{(C₆F₅)₂Pd} ₂(μ-OH)(μ-η²-MeimidS)]. The analogous mixed platinum complex [NBu₄]₂[{(C₆F₅)₂Pd} ₂(μ-OH)(μ-η²-MeimidS)] was prepared by reaction of [NBu₄]₂[{(C₆X₅) ₂Pt(μ-OH)₂}₂] with the corresponding heterocyclic thione H(LL′) in 1:1 molar ratio. The crystal structure of [NBu₄]₂[{(C₆F₅) ₂Pd(μ-η²-MeimidS)}₂], determined by X-ray diffraction, confirmed the dimeric structure with a head-to-tail arrangement. C₆₄H₈₂F₂₀N₆Pd₂S ₂, orthorhombic Pca2₁, a=19.552(8), b=25.160(3), c=14.727(3) A?, Z=4.