A new series of nonoxido vanadium(IV) compounds [VL2] (L = L1?L3) (1?3) have been synthesized using dithiocarbazate-based tridentate Schiff-base ligands H2L1?H2L3, containing an appended phenol ring with a tert-butyl substitution at the 2-position. The compounds are characterized by X-ray diffraction analysis (1, 3), IR, UV-vis, EPR spectroscopy, and electrochemical methods. These are nonoxido VIV complexes that reveal a rare distorted trigonal prismatic arrangement around the ?bare? vanadium centers. Concerning the ligand isomerism, the structure of 1 and 3 can be described as intermediate between mer and sym-fac isomers. DFT methods were used to predict the geometry, g and 51V A tensors, electronic structure, and electronic absorption spectrum of compounds 1?3. Hyperfine coupling constants measured in the EPR spectra can be reproduced satisfactorily at the level of theory PBE0/VTZ, whereas the wavelength and intensity of the absorptions in the UV-vis spectra at the level CAM-B3LYP/gen, where ?gen? is a general basis set obtained using 6-31+g(d) for S and 6-31g for all the other elements. The results suggest that the electronic structure of 1?3 can be described in terms of a mixing among V-dxy, V-dxz, and V-dyz orbitals in the singly occupied molecular orbital (SOMO), which causes a significant lowering of the absolute value of the 51V hyperfine coupling constant along the x-axis. The cyclic voltammograms of these compounds in dichloroethane solution display three one-electron processes, two in the cathodic and one in the anodic potential range. Process A (E1/2 = +1.06 V) is due to the quasi-reversible V(IV/V) oxidation while process B at E1/2 = ?0.085 V is due to the quasi-reversible V(IV/III) reduction, and the third one (process C) at a more negative potential E1/2 = ?1.66 V is due to a ligand centered reduction, all potentials being measured vs Ag/AgCl reference.

Nonoxido Vanadium(IV) Compounds Involving Dithiocarbazate- Based Tridentate ONS Ligands: Synthesis, Electronic and Molecular Structure, Spectroscopic and Redox Properties / S., Kundu; D., Mondal; K., Bhattacharya; A., Endo; D., Sanna; Garribba, Eugenio; M., Chaudhury. - In: INORGANIC CHEMISTRY. - ISSN 0020-1669. - 54:(2015), pp. 6203-6215. [10.1021/acs.inorgchem.5b00359]

Nonoxido Vanadium(IV) Compounds Involving Dithiocarbazate- Based Tridentate ONS Ligands: Synthesis, Electronic and Molecular Structure, Spectroscopic and Redox Properties

GARRIBBA, Eugenio
;
2015-01-01

Abstract

A new series of nonoxido vanadium(IV) compounds [VL2] (L = L1?L3) (1?3) have been synthesized using dithiocarbazate-based tridentate Schiff-base ligands H2L1?H2L3, containing an appended phenol ring with a tert-butyl substitution at the 2-position. The compounds are characterized by X-ray diffraction analysis (1, 3), IR, UV-vis, EPR spectroscopy, and electrochemical methods. These are nonoxido VIV complexes that reveal a rare distorted trigonal prismatic arrangement around the ?bare? vanadium centers. Concerning the ligand isomerism, the structure of 1 and 3 can be described as intermediate between mer and sym-fac isomers. DFT methods were used to predict the geometry, g and 51V A tensors, electronic structure, and electronic absorption spectrum of compounds 1?3. Hyperfine coupling constants measured in the EPR spectra can be reproduced satisfactorily at the level of theory PBE0/VTZ, whereas the wavelength and intensity of the absorptions in the UV-vis spectra at the level CAM-B3LYP/gen, where ?gen? is a general basis set obtained using 6-31+g(d) for S and 6-31g for all the other elements. The results suggest that the electronic structure of 1?3 can be described in terms of a mixing among V-dxy, V-dxz, and V-dyz orbitals in the singly occupied molecular orbital (SOMO), which causes a significant lowering of the absolute value of the 51V hyperfine coupling constant along the x-axis. The cyclic voltammograms of these compounds in dichloroethane solution display three one-electron processes, two in the cathodic and one in the anodic potential range. Process A (E1/2 = +1.06 V) is due to the quasi-reversible V(IV/V) oxidation while process B at E1/2 = ?0.085 V is due to the quasi-reversible V(IV/III) reduction, and the third one (process C) at a more negative potential E1/2 = ?1.66 V is due to a ligand centered reduction, all potentials being measured vs Ag/AgCl reference.
2015
Nonoxido Vanadium(IV) Compounds Involving Dithiocarbazate- Based Tridentate ONS Ligands: Synthesis, Electronic and Molecular Structure, Spectroscopic and Redox Properties / S., Kundu; D., Mondal; K., Bhattacharya; A., Endo; D., Sanna; Garribba, Eugenio; M., Chaudhury. - In: INORGANIC CHEMISTRY. - ISSN 0020-1669. - 54:(2015), pp. 6203-6215. [10.1021/acs.inorgchem.5b00359]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/78803
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 40
  • ???jsp.display-item.citation.isi??? 40
social impact