Synthesis, characterization, NMR spectroscopic, and X-ray crystallographic studies of new titanium(IV) Schiff base salen complexes: Formation of intriguing titanium(IV) species

摘要

The H(2)salen ligand 1 was used as a precursor ligand to produce a series of new complexes, [Ti(salen)(OPh-m-CH3)(2)] 2 (where salen = N,N'-ethylenebis(salicylideneiminate) dianion and -OPh-m-CH3 = 3-methylphenolato), [Ti(salen)(OPh-p-NO2)(2)] 3 (where -OPh-p-NO2 = 4-nitrophenolato), [Ti(salen)(3,5-bis(trifluoromethyl) phenolate)(2)] 4, Ti(salen)(OPh)(2)] 5a (where - OPh = phenolato), [Ti(salen)(OPh-o-F)(2)] 6a (where - OPh-o-F = 2-fluorophenolato), [Ti(salen)(OPh-p-CH3)(2)] 7a (where -OPh-p-CH3 = 4-methylphenolato), [Ti(salen) (OPh-o-CH3)(2)] 8 (where -OPh-o-CH3 = 2-methylphenolato), [Ti(salen)(OPh-m-F) 2 ] 9 (where -OPh-m-F = 3-fluorophenolato), and [Ti(salen)(OPh-p-F)(2)] 10 (where - OPh-p-F = 4-fluorophenolato). The ligand and the complexes were characterized by elemental analysis, FTIR, H-1, F-19, and Ti-49 NMR spectroscopies, and X-ray crystallography. All the complexes, as synthesized, were consistent as mononuclear titanium(IV) complexes, but complexes 5b, 6b, and 7b after being characterized by X-ray crystallography were found to be binuclear in nature. Ti-49 NMR spectroscopic studies proved that this is the very first report of Ti-49 NMR spectra of titanium (IV) complexes with Schiff bases as ligands in deuterated chloroform.