Transition metal complexes with thiosemicarbazide-based ligands, Part 58. Synthesis, spectral and structural characterization of dioxovanadium(V) complexes with salicylaldehyde thiosemicarbazone

Ljiljana Vojinovic-Jesic, Vukadin Leovac, Mirjana Lalovic, Valerija Cesljevic, Ljiljana Jovanovic, Marko Rodic, Vladimir Divjakovic
2011 Journal of the Serbian Chemical Society  
The first two complexes of dioxovanadium(V) with salicylaldehyde thiosemicarbazone (SALTSC), of the coordination formulas [VO 2 (SALTSC--H)]·H 2 O (1) and NH 4 [VO 2 (SALTSC-2H] (2), were synthesized and characterized by elemental analysis, conductometric measurements, IR and UV-Vis spectroscopy and X-ray analysis. The complexes were obtained in the reaction of an aqueous ammoniacal solution of NH 4 VO 3 and SALTSC. The results of the characterization showed that SALTSC was coordinated in the
more » ... ual ONS tridentate mode as monoanion in complex 1 and dianion in complex 2. In both complexes, the vanadium atom is in a deformed square-pyramidal environment and is slightly shifted towards the apical oxo-ligand (≈ 0.52 Å). 866 VOJINOVIĆ-JEŠIĆ et al. bered (thiosemicarbazide) (Fig. 1a) . Experiments have shown that SALTSC can also be coordinated as a tridentate dianion (Fig. 1b) after deprotonation of the thiosemicarbazide residue in its thiol form, which is regulated by the pH value. Another two coordination modes of this ligand are bidentate through N3 and S1, by which one 4-membered metallocycle is formed (Fig. 1c ) 2 and monodentate through S1. 3 Only one exception to this rule is known and that is the complex of MoO 2 (VI), in which SALTSC is coordinated as a tridentate ONN ligand, via the amide N1 atom instead of the usual thionic S1 atom (Fig. 1d) . 4 This coordination mode is characteristic for S-alkyl-thiosemicarbazide derivates, i.e. isothiosemicarbazides and isothiosemicarbazones. 5
doi:10.2298/jsc101217078v fatcat:4qy33467gvaszga4ic5ke3ukwi