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Spectroscopic and Structural Characterization of Noninnocent Mixed‐Ligand Oxidovanadium(V) Complexes
Author(s) -
Maurya Mannar R.,
Bisht Manisha,
Chaudhary Nikita,
Kumar Amit,
Avecilla Fernando,
Costa Pessoa João
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200656
Subject(s) - chemistry , octahedron , ligand (biochemistry) , catechol , metal , crystallography , pyridine , nuclear magnetic resonance spectroscopy , stereochemistry , methylene , crystal structure , medicinal chemistry , organic chemistry , biochemistry , receptor
The reaction between [V IV O(acac)(L)] and the potentially noninnocent ligands catechol (H 2 cat/cat 2– ) and benzohydroxamic acid (H 2 bha/bha 2– ), where HL = Hpydx‐aebmz, Hpydx‐dmen, Hpydx‐aepy [ONN donor Schiff bases obtained by condensation of pyridoxal and 2‐(2‐aminoethyl)benzimidazole (Hpydx‐aebmz), 2‐(2‐aminoethyl)pyridine (Hpydx‐aepy), or N , N ‐dimethylethylenediamine (Hpydx‐dmen)], or HL = Hpan [1‐(2‐pyridylazo)‐2‐naphthol], in equimolar amounts results in the formation of the distorted octahedral complexes [V V O(cat)(L)] and [V V O(bha)(L)]. The molecular structure of [VO(bha)(pydx‐dmen)] is determined by single‐crystal X‐ray diffraction and confirms the distorted octahedral geometry as well as the ONN and OO binding modes of pydx‐dmen – and bha 2– , respectively, in their binding to the V V O centre. The noninnocent catechol 2– and bha 2– ligands play significant roles in the electronic properties of the metal complexes investigated by UV/Vis, IR, and 51 V NMR spectroscopy. Evidence for the noninnocent behavior of catechol 2– and bha 2– ligands was obtained; the [V V O(cat)(L)] and [V V O(bha)(L)] complexes exhibit 51 V NMR resonances ( δ V ) in the range +535 to –10 ppm and intense ligand‐to‐metal charge‐transfer bands in the visible and near infrared range. The observed δ V chemical shifts linearly correlate with the inverse of the energies of the LMCT transitions.