Oxo-bridged bis oxo-vanadium(V) complexes with tridentate Schiff base ligands (VOL)2O (L=SAE, SAMP, SAP): Synthesis, structure and epoxidation catalysis under solvent-free conditions

Abstract

The dinuclear V(V) complexes (VOL)2O (L= SAE (1), SAMP (2), SAP (3)) have been synthesized from VO(acac)2 and the corresponding tridentate ligands LH2 in methanol under reflux conditions and subsequent air oxidation in organic solvent. They have been characterized by IR and NMR spectroscopy, by thermogravimetric analysis, and by single crystal X-ray diffraction for 1 and 2. DFT calculations were carried out for a better understanding of the vibrational pattern, principally the V-O related vibrations. Complex [VO(SAP)]2O (3) catalyzes the epoxidation of cyclooctene by TBHP in water in the absence of any added solvent with good selectivity.

Schiff base‐functionalized boehmite nanoparticle‐supported molybdenum and vanadium complexes: efficient catalysts for the epoxidation of alkenes

“…[1][2][3][4] In the last decade, several soluble Schiff base complexes of Cr, [4,5] Mo, [4,6,7] Re, [8] Ni, [9] Co, [10,11] Mn, [12,13] V, [14][15][16][17] Cu, [18] Ru [19] and Ti [20] have been employed as active homogeneous catalysts in the epoxidation of alkenes. However, most of these catalysts are expensive and contaminate the environment.…”

Substituent effects on solvent-free epoxidation catalyzed by dioxomolybdenum(VI) complexes supported by ONO Schiff base ligands

“…Diminishing or avoiding the use of organic solvents is one of the challenges of green chemistry to be taken into account. We are currently studying the solventfree epoxidation of olefins using coordination complexes of molybdenum [7], vanadium [8] and polyoxometalates [9]. Within these investigations, we have shown that the molybdenum complexes with the salicylidenaminophenolato (SAP) Schiff base ligand are stable and active under solvent-free conditions.…”

“…With the aim of designing a cleaner process, we are exploring solvent-free epoxidation conditions[7][8][9], i.e. using aqueous TBHP as oxidant (water only being the oxidant carrier and not a solvent for the catalytic reaction) and no added organic solvent.All complexes have been tested under the same experimental solvent-free conditions and using the same substrate (cyclooctene) already used for the previously reported epoxidation with [MoO 2 (L 1 )] 2 [7c] in order to evaluate the potential role of the substituents in the ligand backbone on the catalytic activity.…”

Synthesis, characterization and crystal structures of oxovanadium(V) complexes derived from similar aroylhydrazone ligands

“…Schiff bases are a kind of interesting ligands in coordination chemistry [10][11][12][13][14][15]. In recent years, a number of vanadium complexes with Schiff bases derived from salicylaldehyde and primary amines have been reported [16][17][18][19][20]. Hydrazones, bearing -C(O)-NH-N=CH-groups, are a kind of special Schiff bases, which are of particular interest in coordination chemistry and biological applications.…”