Synthesis, spectral, DFT and X-ray study of a cis-MoO₂ complex with a new isothiosemicarbazone ligand

Abstract

2,4-Dihydroxybenzaldehyde S-allylisothiosemicarbazone hydrobromide, H₂L, reacts with dioxo-molybdenum acetylacetonate in methanol to form a stable complex of dioxomolybdenum(VI). The ligand and complex are characterized with analytical and spectroscopic techniques. Single-crystal X-ray crystallography has been also carried out for the complex, showing it has distorted octahedral geometry. H₂L is a tridentate dianionic ligand bonded as an ONN donor to molybdenum. Thermogravimetric analysis of the complex shows MoO₃ as the final product above 780 °C. The results obtained from density functional theory calculations for the optimization and frequency analysis are in agreement with the experimental data. Natural bond orbital calculations show that the majority of the electron density of the donors tends to the molybdenum, since the calculated Mulliken charge for the central ion is much lesser than the formal value.

Keywords:

• Isothiosemicarbazone
• Molybdenum(VI) complex
• TG
• Crystal structure
• DFT

Acknowledgements

We would like to appreciate the Tulane Crystallography Laboratory of Chemistry Department, Tulane University, for their invaluable help. Also, we are thankful of Ferdowsi University of Mashhad and Payame Noor University (PNU) for their support.