The Coordination Chemistry of N-(3-Carboxylphenyl) Pyridine-2′-Carboxamide

Abstract

New complexes of the general compositions M(LH₂)₂X₂ (M = Co, Ni, Cu, Zn; X = Cl, NCS, NO₃), M(LH₂)₂Cl₂. EtOH (M = Ni, Cu; EtOH = ethanol), M(LH)₂.nH₂O (M = Co, Ni, Cu, Zn, Pt; n = 1, 2, 3), Pd(LH)Cl·H₂O, CuL·3H₂O and Zn(LH) (OH) ·2H₂O, where LH₂ = N-(3-carboxylphenyl)pyridine-2′-carboxamide, have been isolated. The complexes were characterised by elemental analyses, conductivity measurements, TG patterns, magnetic susceptibilities and spectral (¹H-NMR, IR, electronic) studies. Distorted octahedral and square planar stereochemistries are assigned in the solid state. Coordination of the neutral carboxylic group is not observed for the complexes of LH₂; the carboxylate ion exhibits monodentate coordination in the compounds of LH⁻ and L^2-. The neutral amide group of LH₂ and LH⁻ is coordinated to Co(II), Ni(II), Cu(II) and Zn(II) through oxygen, while nitrogen and oxygen amide coordination is observed for CuL·3H₂O. The secondary amide bond shows the rare iminol type of coordination in Pd(LH)Cl·H₂O.