The IR spectra of the Schiff base ligands (1a-3a) exhibit a strong band in the range 3026-3180 [cm.sup.-1]and 1672-1679 [cm.sup.-1] due to vNH and vC=O groups respectively, which disappears in the corresponding complexes suggesting the enolization of the -C=O of the aroyl keto group giving rise to the -C=N-N=C moiety [15 ] and consequent deprotonation upon coordination.
The absence of these signals in the spectra of the complexes indicate coordination through the phenolic oxygen and enolization of the -C=O of the aroyl keto group and consequent deprotonation.
We used PdC[1.sub.2][(P[h.sub.3]P).sub.2] with [K.sub.2]C[O.sub.3], as a new catalyst system, for the synthesis of fluoro-substituted ketones from potassium aryltrifluroborates and aroyl
Hegazy, "Update survey on aroyl
substituted thioureas and their applications," Journal of Sulfur Chemistry, vol.
Key words: Vanadium complexes, Bacillus pasteurii, Canavalia ensiformis (Jack bean), Urease inhibition, Enzyme kinetics, Aroyl hydrazine
Rao, Oxovanadium Binuclear (IV) Schiff Base Complexes Derived from Aroyl Hydrazones having Subnormal Magnetic Moments, Polyhedron, 16, 1825 (1997).