Complexes of some transition metal ions with 2-methyl-1-vinylimidazole in aqueous solution and the solid state

Abstract

The stability constants and structures of the complexes of Co²⁺, Cu²⁺, Zn²⁺, Ni²⁺ and Cd²⁺ with 2-methyl-1-vinylimidazole in aqueous solution have been determined by potentiometric and spectrophotometric methods. The stability of the compounds depended much on the presence of the electron-attracting vinyl substituent contributing to the π_M→L back bonding. Further, nitrato complexes of cobalt(II) and copper(II) with 2-methyl-1-vinylimidazole (L) of general formulae [CoL₃(H₂O)(NO₃)]NO₃1, [CoL₂(NO₃)₂] 2, [CuL₄(NO₃)₂]·2H₂O 3 and [CuL₂(NO₃)₂] 4 have been prepared in the solid state. Full single-crystal X-ray analyses have been accomplished for compounds 1 and 4 which enabled the determination of angles and bond lengths.The compounds were identified on the basis of elemental analyses, EPR spectroscopy, IR, FIR and VIS-NIR absorption spectra and magnetochemical data. The immediate environment of the central ions is described by a distorted tetragonal bipyramid.