Novel complexes of silver(i) sulfate with 1-methylimidazole-2-thione: structures and vibrational spectroscopy

Abstract

Crystallization of silver(I) sulfate with the ligand 1-methylimidazole-2-thione (‘Hmimt’) from aqueous solution, instead of yielding the expected 1 : 6 Ag₂SO₄ : Hmimt complex analogous to numerous other Ag₂SO₄ : thiourea-based ligand (1 : 6) complexes, has resulted in novel polymeric forms, one of unusual stoichiometry. Ag₂SO₄ : Hmimt (1 : 4) (·H₂O) is of the form [⋯(μ-Hmimt)₂Ag(μ-Hmimt)₂Ag⋯](∞|∞)(SO₄), with a one-dimensional polymeric cation. Ag₂SO₄ : Hmimt (3 : 8) (·9½H₂O) is a polymeric sheet structure containing Ag₁₂(SO₄)₆(Hmimt)₁₅ kernels linked by Hmimt ligands. The IR spectra of these compounds show unusually large shifts of the ν(NH) band due to the presence of N–H⋯O hydrogen bonding involving the N–H group of the ligand and the sulfate oxygen atoms. The complexes were also readily prepared by the solvent-assisted mechanochemical method, and the utility of this method for the preparation of deuterium-exchanged products for assistance in the assignment of the IR spectra is illustrated.