Synthesis of mixed-ligand complexes of VO2+ and VO3+ incorporating hydrazone, 1, 10-phenanthroline and 8-hydroxyquinoline. Issue 2 (17th January 2016)

• Record Type: Journal Article
• Authors: Biswas, Nirmalendu; Patra, Debashis; Mondal, Bipul; Drew, Michael G.B.; Ghosh, Tapas
• Is Part Of: Journal of coordination chemistry. Volume 69:Issue 2(2016)
• Page Start: 318
• Page End: 329
• Publication Date: 2016-01-17
• Subjects: V(IV) and V(V) complexes -- hydrazone complexes -- X-ray structure -- electrochemistry -- EPR spectra, DFT study; Coordination compounds -- Periodicals; 541.2242
• DOI: 10.1080/00958972.2015.1107054
• Languages: English
• ISSNs: 0095-8972

Abstract

Abstract: 2-Aminobenzoylhydrazide (abh) reacts with equimolar amounts of either [V IV O(acac)2 ] or [V IV O(bzac)2 ] (where acac − and bzac − are the monoanionic forms of acetylacetone (Hacac) and benzoylacetone (Hbzac), respectively) in the presence of equimolar amounts of 1, 10-phenanthroline (phen) to form the octahedral mixed-ligand complexes [V IV O(L 1 )(phen)] (1 ) and [V IV O(L 2 )(phen)] (2 ), where (L 1 ) 2− and (L 2 ) 2− are the dianionic forms of the 2-aminobenzoylhydrazone of acetylacetone (H2 L 1 ) and benzoylacetone (H2 L 2 ). Upon substituting phen by 8-hydroxyquinoline (Hhq), pentavalent [V V O(L 1 )(hq)] (3 ) and [V V O(L 2 )(hq)] (4 ) complexes were instead obtained. In the crystal structures of3 and4, the hydrazone ligands coordinate to the vanadium center through the enolic-O, one imine-N and amide-O in a mer geometry. The amine and the second imine nitrogen form intramolecular hydrogen bonds. Complexes1 and2 display quasi-reversible one-electron oxidation peaks near +0.60 V, while the pentavalent3 and4 exhibit quasi-reversible one-electron reduction peaks near −0.18 V versus Ag/AgCl in CH2 Cl2 solution. EPR spectroscopic studies on1 and2 suggest that the unpaired electron is present in the dxy orbital. DFT studies for3 indicate that the dxy orbital of vanadium is the main contributor to the LUMO. Abstract :