Sulphur-nitrogen chelating agents. III. Metal complexes of 2-methylthiomethylpyridine

Abstract

Complexes of 2-methylthiomethylpyridine (mmp) have been obtained with cobalt(II), nickel(II), copper(II), copper(I), palladium(II), platinum(II), silver(I), and mercury(II). The compounds MX₂ mmp₂ (M = Co, Ni; X = Cl, Br, SCN) and NiI₂ mmp₂ are high-spin and their reflectance spectra indicate that the complexes are octahedral in the solid state. The visible absorption spectrum of CoCl₂ mmp₂ in nitrobenzene indicates that the complex is tetrahedral in solution with the ligand probably coordinated through the pyridine nitrogen only. The tris-chelated complexes [M mmp₃](ClO₄)₂ were also characterized. Spectral data indicate that the complexes CuX₂ mmp (X = Cl, Br) possess a tetragonal polymeric structure in the solid state. Conductimetric titration of the perchlorate [Cu mmp₂](ClO₄)₂ with chloride ion in nitromethane demonstrated the formation of [CuCl mmp₂]⁺ in solution. This was confirmed by the isolation of [CuCl mmp2]ClO₄ and [CuBr mmp₂]ClO₄. The bis-chelated complex CuCl₂ mmp₂ gives a solution in nitrobenzene which is virtually non-conducting. The complexes PdX₂ mmp (X = Cl, Br, I, SCN), Pt(SCN)₂ mmp, [M mmp₂]- (ClO₄)₂ (M = Pd, Pt, Hg), [Pt mmp₂][PtCl₄], and [Cu mmp₂]ClO₄ were also isolated. The silver(I) complex Ag mmp ClO₄ probably contains the dimeric cation [Ag₂ mmp₂]²⁺.