Palladium and platinum complexes of 2-(2′-carboxyphenylazo)-4-methylphenol: synthesis, structure and spectral properties

Abstract

Reaction of 2-(2′-carboxyphenylazo)-4-methylphenol (H₂L) with [M(PPh₃)₂Cl₂] (M = Pd, Pt) affords mixed-ligand complexes of type [M(PPh₃)(L)]. Structures of both the complexes have been determined by X-ray crystallography. Both the complexes are square planar, where the 2-(2′-carboxyphenylazo)-4-methylphenol is coordinated to the metal center, via dissociation of the two acidic protons, as a dianionic tridentate O,N,O-donor, and the fourth position is occupied by the triphenylphosphine. These complexes show intense MLCT transitions in the visible region.