Complexes of cis-dioxomolybdenum(VI) and oxovanadium(IV) with a tridentate ONS donor ligand: Synthesis, spectroscopic properties, X-ray crystal structure and catalytic activity

Oxovanadium(IV) and ruthenium(II) carbonyl complexes of ONS‐donor ligands derived from dehydroacetic acid and dithiocarbazate: Synthesis, characterization, antioxidant activity, DNA binding and in vitro cytotoxicity

“…In complex 2.2 , the bonds O25─V1, N33─V1 and S2─V1 (Table ) also show a significant trans effect. The C3─N6 and C8─N7 lengths are both 1.29(1) Å in 1.1 and around this value in 2.2 , and this consistent with Cd─N bond length . The longer bond lengths C3─S2 (1.72(1)Å) for 1.1 and C3─S2 (1.73(1)Å) for 2.2 are close to those found for N, N, S‐donor ligands chelated in their thiolate form .…”

“…The paramagnetic oxovanadium(IV) complexes in the solid state at room tempaerature exhibit only one line with g av values of 1.98–1.99 which are less than g e of the free electron ( g e = 2.0023) (Figure ) . Comparing these data with those calculated from d–d transitions of these complexes (using equations and ), it was found that calculated g av values are coincident with experimental data. where c 1 is equivalent to 0.907 and 0.946 for the first and second excited states, respectively, and λ is the spin–orbit coupling parameter (equal to 135 cm −1 ) and g av = 1/3( g || + 2 g ⊥ ).…”

“…UV–visible spectra of octahedral vanadium(IV) complexes (associated with 3d 1 4s 0 configuration) show strong absorption bands around 325–400 nm due to both intra‐ligand charge transfer and metal‐to‐ligand charge transfer (MLCT) transitions . The two weak broad bands at 756–635 nm were as expected for d–d transitions ( 2 B 2 (d xy ) → 2 E(d xz , d yz ) and 2 B 2 (d xy ) → 2 B 1 (d x 2 ‐ y 2 )) . Electronic spectra of the ruthenium(II) complexes show distinct bands at 360, 400 and 570 nm that are probably assigned to allowed MLCT and d–d transitions which are similar to those of other reported low‐spin (4d 6 , t 2 g 6 ) octahedral ruthenium(II) complexes …”

“…Similar related bond parameters (Table ) are found for complex 2.2 , indicating the same distorted octahedral environment. Complexes containing O, N, S‐dibasic ligands have similar coordination geometry . The shortest and longest bonds in 1.1 formed by the metal atom are V1d─O19 (1.600 Å) and V1─N20 (2.315(9) Å) having a trans influence of the oxo‐atom .…”

“…All the oxovanadium(IV) complexes were synthesized following a general procedure based on literature methods …”