Metal complexes of N-2-thenylsalicylaldimine

Abstract

The ligand isomeric complexes of N-2-thenylsalicylaldimine with Pd^II were synthesised. The nature of the isomerism was characterised by the ¹H n.m.r. spectral data for the azomethine group, CN group i.r. frequencies, and u. v. spectra. The complexes with Cr^III, Fe^III, Co^III, Ni^II, Cu^II, and Pt^II were obtained in the isomeric form (A), i.e. SC₄H₃CH₂NCHC₆H₄OH-o, and those of V^IV and Zn^II were obtained in the isomeric form (B), i.e. SC₄H₃CHNCH₂C₆H₄OH-o. From its solubility characteristics and ¹H n.m.r. spectra, the palladium(II) complex containing ligand isomer (A) was shown to be a binuclear complex in which the phenolic oxygen displays three-co-ordination. The subnormal magnetic moment at room temperature and the cryomagnetic data of the copper(II) complex suggested a similar binuclear configuration having a large antiferromagnetic interaction (J=–175 cm^–1, g= 2.4). The cryomagnetic data of the iron(III) complex indicated a thermal equilibrium between nearly equi-energetic spin-paired (²T₂) and spin-free (⁶A₁) configurations of iron(III). Co-ordination of the thiophene sulphur was indicated in the (B) isomeric form of the complexes of Pd^II and Zn^II.