Synthesis and characterization of a new thiohydrazone ligand, 3-carboxy-2-hydroxybenzaldehydemorpholine N-thiohydrazone and its metal complexes

Synthesis, structural characterization and thermal properties of three copper(II) complexes based on aryl hydrazide ligands

“…As for the ligand H 2 L 1 , it has evidently lost two protons and acts as a pentadentate ligand by chelating two copper atoms in fused 5-5-5 rings. The C1-S1 bond length of 1.731(3) Å is within the normal distance range of C-S single bonds, indicating the (L 1 ) 2-moieties adopt the thiol tautomeric form [23,24]. An interesting feature of complex 1 is the supramolecular framework assembled by various non-covalent forces.…”

Coordination complexes of titanium, zirconium and tin having metal-carbon bonds with dibasic NSO donor Schiff base ligand. Syntheses and characterization

“…Therefore, the thione form H 2 chbmth and the thiol form H 3 chbmthol may remain in equilibrium in solution (figure 1). It was observed by us earlier [8] that the reactions of H 2 chbmth with different metal salts under varied reaction conditions yielded complexes of the corresponding thiol form of the ligand where it functions as dibasic tridentate fashion bonding through O, N and S atoms with different metal ions. Neutral and bidentate behaviour was also encountered in certain cases with bonding through thione S and azomethine N [8].…”

“…It was observed by us earlier [8] that the reactions of H 2 chbmth with different metal salts under varied reaction conditions yielded complexes of the corresponding thiol form of the ligand where it functions as dibasic tridentate fashion bonding through O, N and S atoms with different metal ions. Neutral and bidentate behaviour was also encountered in certain cases with bonding through thione S and azomethine N [8]. However, in the present study the ligand uniformly acts as dibasic tridentate, bonding through thiol S (after deprotonation), azomethine N and phenolic O (after deprotonation) and the carboxylic acid group was always found to be free without participation in complex formation (schemes 1 and 2).…”

“…The tuberculostic properties of hydrazides and their derivatives have also been extensively studied [2] and the condensation products of hydrazides with different carbonyl compounds (aldehydes/ketones) are known to be less toxic than the parent hydrazides; this is probably due to the blocking of the free amino group. Because of this and as a part of our systematic studies of hydrazide and hydrazone ligands [3][4][5][6][7], we have very recently synthesized 3-carboxy-2-hydroxybenzaldehyde morpholine N-thiohydrazone (H 2 chbmth) by condensation of 3-formylsalicylic acid with morpholine N-thiohydrazide and studied its reactions with first and second row transition metal salts under varied reaction conditions [8], isolating many new metal complexes of the ligand H 3 chbmthol which is the thiol form of the hydrazone H 2 chbmth (figure 1) [9]. In most of the cases H 3 chbmthol functions as a dibasic tridentate NSO donor ligand, the COOH group remaining free.…”

Synthesis, optical and thermal behaviour of palladium(II) complexes with 4-(4-alkoxy-2-hydroxybenzylideneamino)azobenzene

“…This observation can be ascribed to the reduction of double bond character of the C=N bond and it is in agreement with the results obtained from other analogous complexes. 5,[9][10][11]14,17,18 Besides, a weak band at 1471-1473 cm −1 indicates the stretching frequency of azolinkages of N=N. 19 Since this band is not shifted upon complex formation, therefore, the coordination of the N atom from the azo-linkages to Pd(II) ion can be ruled out.…”