Abstract
Four Cu(II) complexes of N
1
-phenyl-N
2
-(pyridin-2-yl)hydrazine-1,2-bis(carbothioamide) (H
2
PPS), N-phenyl-2-(2-(pyridin-2-ylcarbamothioyl)hydrazinyl)-2-thioxoacetamide (H
2
PBO), N-phenyl-2-(pyridin-2-ylcarbamothioyl)hydrazinecarboxamide (H
2
APO), and 1-(aminoN-(pyridin-2-yl)methanethio)-4-(pyridin-yl)thiosemicarbazide (H
2
PPY) have been prepared and characterized by elemental analyses, spectral (infrared (IR), UV-Visible,
1
H NMR, and electron spin resonance (ESR)) as well as magnetic and thermal measurements. Varying the substituents on the thiosemicarbazide led to remarkable modifications of the mode of coordination. IR spectral data reveal that the ligands are SN bidentate, NON tridentate, or NSNS tetradendate chelates forming structures in which copper is square-planar or octahedral. ESR spectra of these complexes are quite similar and exhibit an axially symmetric g-tensor parameter with g
|
> g
⊥
> 2.0023 revealing an appreciable covalency with d(
x
2
-y
2
) as the ground-state. Bond lengths, bond angles, HOMO, LUMO, and dipole moments have been calculated to confirm the geometry of the thiosemicarbazide derivatives and their corresponding complexes. Proton-ligand dissociation and copper-ligand stability constants of all ligands were calculated pH-metrically. The effect of the compounds on calf thymus DNA was investigated.