Coordination compounds of hydrazine derivatives with transition metals—XV Electronic and 1H NMR spectra of some diamagnetic metal(II) chelates with bidentate Schiff bases derived from hydrazine-S-methyl-dithiocarboxylate and thiosemicarbazide

Abstract

A series of diamagnetic bis ligand Zn(II), Cd(II), Hg(II), Ni(II) and Pd(II) chelates with some Schiff bases derived from hydrazine-S-methyldithiocarboxylate(III) and the corresponding acid amide(IV) were prepared and characterized. The H NMR spectral studies showed that the Schiff base ligands derived from aromatic aldehydes as well as their metal(II) chelates exist only in one configuration with the aldehydic hydrogen syn to the NN bond. The ligand (III) derived from asymmetric ketones exist as a mixture of syn and anti configurations. The H NMR spectra of the corresponding Zn(II), Cd(II), Hg(II) and Ni(II) chelates indicate the presence of a trans isomer in syn and anti configurations. The spectra of Pd(II) chelates with ligand (III) show the possible existence of both cis and trans isomers in both syn and anti configurations. Besides, the syn and anti configurations, the Zn(II) and Ni(II) chelates with (III, R 1 = CH 3, R 2 = CH 2C 6H 5) appear to exist in different conformations. Ni(II) chelates derived from acetophenone derivatives exist predominantly in cis-syn configuration.