Demetallation of coordination compounds of nickel with tetradentate ligands based on S-substituted isothiosemicarbazides

Abstract

The passage of dry gaseous hydrogen chloride through chloroform solutions or acetone suspensions of S-substituted N¹,N⁴-di(salicylidene)isothiosemicarbazidates of nickel (Ni(LRR′)) has led to a demetallization reaction with the liberation in the free state of S-substituted N¹,N⁴-di(salicylidene)isothiosemicarbazides with the general formula N₂LRR′ (where R is H and R′ is CH₃ (I); R is H and R′ is C₂H₅ (II); R is H and R′ is C₃H₇ (III); R is H and R′ is C₇H₇ (IV); and R is CH₃ and R′ is CH₃ (V)). The IR spectra of (I-IV) each showed bands characteristic for an aromatic ring and

groups in the 1600–1500 cm⁻¹ region, with a band of the deformation vibrations of an OH group at 1300 cm⁻¹. The PMR spectra in CDCl₃ each had two singlets at 12.15-11.25 and 9.00-8.36 ppm which were assigned, respectively, to the protons of an OH group and those of a =CH group. A multiplet in the 7.70-6.83 ppm region belonged to the protons of benzene rings. In the region of lower fields there were the signals of the substituents R and R′. In the mass spectra of (I-V), the peaks of the molecular ions, and also the characteristic fragments OH, R′, SR′, and HSR′ have been detected.