Structural and spectroscopic parameters of distortion in [Cu(bpy)2(O2SO2)]·CH3OH and [Cu(bpy)3][SO4]·7.5H2O – Synthesis, crystal structure, spectroscopic and magnetic properties

A copper(II) sulfate complex of formula [Cu(bpy)2(O2SO2)]·CH3OH (1) (bpy = 2,2′-bipyridine) was prepared and characterized by X-ray diffraction, spectroscopic methods (FIR, IR, NIR–Vis–UV, EPR) and magnetic measurement. The S–O distances in the chelating SO42- entity give the value of the geometric distortion parameter Δr = 0.022. The EPR g parameters are temperature dependent and indicated the fluxional model of the [Cu(N,N′)2OO] chromophore with dx2-y2dx2-y2 ground state. The electronic spectrum of 1 exhibits the maxima at 9740 and 14 630 cm−1. The very weak antiferromagnetic interaction between copper centers in the crystal lattice was observed.In [Cu(bpy)3][SO4]·7.5H2O (2) crystal the distance values in [Cu(bpy)3]2+ cations result in T = 0.958 and the value of Δr   of the non-coordinate SO42- tetrahedron is 0.095. The value of T for [CuN6] (2) suggests the fluxional character of Jahn–Teller (JT) distortion supported by the EPR studies. The electronic spectrum shows two separated bands at 6900 and 14 400 cm−1.

Graphical abstract[Cu(bpy)2(O2SO2)]·CH3OH (1) and [Cu(bpy)3][SO4]·7.5H2O (2) where bpy = 2,2′bipyridine complexes have been obtained in crystalline form and studied by X-ray crystallography and spectroscopic methods (FIR, IR, EPR, and NIR–Vis–UV). The complex 1 shows the fluxional model of the [Cu(N,N′)2OO] chromophore. The [Cu(bpy)3]2+ cation in structure 2 presents the fluxional character of Jahn–Teller distortion with T = 0.958. Structural (Δr, T) and spectroscopic (Δν3, Δνmax) parameters of distortion in 1 and 2 complexes are reported.Figure optionsDownload full-size imageDownload as PowerPoint slide