Structural, Magnetic, Spectroscopic and Density Functional Theory (DFT) Analysis of Bis ((1-((E)-2-pyridinylmethylidene) semicarbazone) copper(II) sulfate) Dihydrate Complex

Herein we describe the synthesis, structural, spectroscopic and magnetic characterization of a new pentacoordinated bicopper (II) complex containing 2-formylpyridine semicarbazone (HSCpy), referred as complex 1. Each copper core is bound to one N, N, O-tridentate HSCpy ligand and connected to the second metal ion by two m-oxygen sulfato-bridges. The compound shows an extensive association between the neutral complex molecule and water as crystallization solvate through classical N-H center dot center dot center dot O, O-H center dot center dot center dot O and, non-classical C-H center dot center dot center dot O intermolecular hydrogen bonding generating a supramolecular 3-D assembly in the solid state. Jahn-Teller stabilization energies at 5144 cm(-1) and spin orbit coupling constants lambda = -442 cm(-1) were estimated using the electronic spectra and Electron Paramagnetic Resonance data. The variable-temperature (2-300 K) magnetic measurements showed isotropic magnetic interaction between the two copper ions, according to the spin Hamiltonian yielding 2 J values at -0.34 cm(-1) for complex 1, in accordance with a very small antiferromagnetic interaction between copper ions kept apart by 3.24 angstrom. The results are compared to the thiosemicarbazone analogue.