The interaction of 1-methylimidazoline-2(3H)-thione with copper(II) salts

Abstract

The interaction of 1-methylimidazoline-2(3H)-thione (HL¹) with the appropriate copper(II) species in ethanol solution directly produces the blue mixed-valence complexes, [Cu^I ₁₀Cu^II ₂(L¹)₁₂(H₂O)₄]X₂·yH₂O (X = O₂CMe or OH, y= 2; X = ClO₄ or PF₆, y= 0). With CuCl₂·2H₂O the product is dependent on the HL¹ : Cu molar ratio. If HL¹ was in excess, e.s.r. spectroscopy indicated the formation of a ‘Cu^IIS₄’ species, viz. [Cu(HL¹)₄]²⁺, in solution. At a 3:1 (HL¹:Cu) molar ratio (Cu^II added to HL¹) the known copper(I) complex, [Cu₂(HL¹)₄Cl₂] is obtained. However, using a 1.5:1 (HL¹:Cu) molar ratio, and with HL¹ added to Cu^II, the product is a mixed-valence complex formulated as [Cu₂(HL¹)₂Cl₃]. These compounds, and others obtained with imidazolidine-2-thione (HL²) and 4,5-diphenylimidazoline-2(3H)-thione (HL³), have been characterized by spectroscopic techniques. In nitromethane solution HL¹ reacts in the presence of copper to yield the chelate N-donor ligand, bis(1-methylimidazol-2-yl) sulphide (L⁴) in the dimeric complex [Cu₂(L⁴)₂Cl₄].