Structural, spectral and magnetic properties of Ni(ii), Co(ii) and Cd(ii) compounds with imidazole derivatives and silanethiolate ligands

Abstract

A series of new metal heteroleptic complexes have been obtained in simple reactions of 1-(3-aminopropyl)-imidazole (api) and 1,4-bis(imidazol-1-yl)-butane (bbi) ligands with metal silanethiolates or acetylacetonates. The obtained complexes are the coordination polymers [Ni{SSi(tBuO)₃}₂(μ-api)]_n1, [Co{SSi(tBuO)₃}₂(μ-api)]_n2, [Cd{SSi(tBuO)₃}₂(μ-api)·2CH₃OH]_n3, [Cd{SSi(tBuO)₃}₂(μ-bbi)·CHCl₃]_n4 and the dimer [Co{SSi(tBuO)₃}₂(μ-bbi)·3CH₃OH]₂5. Another coordination polymer with the formula [Ni(acac)₂(μ-bbi)·9CHCl₃]_n6 was obtained in the reaction of Ni(acac)₂ with (tBuO)₃SiSH (TBST) and bbi; however, the silanethiolate residue didn't coordinate to the metallic center as intended. The molecular structures of 1–6 were determined by single-crystal X-ray diffraction. Compounds 1–5 were additionally characterized by thermogravimetry (TGA) and powder X-ray diffraction. The emission spectra of the Cd complexes 3 and 4 were recorded in the solid state at ambient temperature, whereas 1, 2 and 5 were subjected to magnetic studies. Variable-temperature magnetic measurements of the polycrystalline sample 1 suggest the presence of weak intra-chain magnetic interactions between the nickel(II) ions. Magnetic studies of 2 and 5 show their paramagnetic behavior. For sample 1 as well as samples 2 and 5, a noticeable influence of single-ion magnetic anisotropy on their magnetic behavior has been revealed.