Synthesis, characterization, spectral, thermal analysis and computational studies of thiamine complexes

Thiamine metal complexes were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility, ESR spectra of Cu(II) complex and EDX for structural investigation of the complexes to know their geometries and mode of bonding. All the manganese, iron, copper, zinc, tungsten and mercury complexes are with octahedral geometry, while cobalt and nickel complexes are with tetrahedral geometry. The selenium and palladium complexes are with square planner geometry, while vanadium complex with stoichiometry (2:1) is with square pyramidal geometry. The thermal properties of the complexes were examined. The kinetic thermodynamic parameters were estimated from the TGA and DTA curves. Molecular modeling of the ligand and its complexes was performed using PC computer to give extra spot lights on the bonding properties of these compounds. Some theoretical studies were carried out to obtain the charges, bond lengths, bond angles and dihedral angles, energies of highest occupied molecular orbital (EHOMO), energies of lowest unoccupied molecular orbital (ELUMO), the separation energy (ΔE), chemical potential, electronegativity, hardness, softness, ionization potential and electron affinity of the studied ligand and its complexes. Correlation analysis was done to explore the relationships between some different parameters of the studied complexes.