Synthesis, crystal structure, spectroscopic, magnetic, theoretical, and microbiological studies of a nickel(II) complex of L-tyrosine and imidazole, [Ni(Im)2(L-tyr)2]·4H2O.

The [Ni(Im)2(l-tyr)2]·4H2O (1) complex was obtained in crystalline form as a product of interaction of l-tyrosine sodium salt, imidazole, and NiSO4. The X-ray structure was determined, and the spectral (IR, FIR, NIR–vis–UV, HF EPR) and magnetic properties were studied. The Ni2+ ion is hexacoordinated by the N and O atoms from two l-tyrosine molecules and by two N atoms of imidazole, resulting in a slightly distorted octahedral [NiN2N2′O2] geometry with a tetragonality parameter T = 0.995. The bands observed in the electronic spectra were ascribed to the six spin-allowed electronic transitions 3B1g → 3Eg and 3B2g, 3B1g → 3A2g and 3Eg, and 3B1g → 3A2g and 3Eg. The spin Hamiltonian parameters g, D, and E, which were determined from high-field HF EPR spectra, excellently reproduced the magnetic properties of the complex. Calculation of the zero-field splitting in the S = 1 state of nickel(II) using DFT and UHF was attempted. The biological activity of the complexes has been tested for antifungal and antibacte...