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

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.