Indole-based mono- and poly-nuclear acyclic chelating systems: syntheses and selected transition metal complexes

The treatment of 3-(4-chlorophenyl)-4,6-dimethoxyindole with phosphoryl chl oride in dimethylformamide generates the regioselective product 3-(4-chloro phenyl)-4,6-dimethoxyindole-7-carbaldehyde. This serves as a valuable ligan d precursor and, on reaction with selected di- and tri-amines, yields a num ber of new acyclic ligands. Treatment of these ligands with selected divale nt transition metal acetates in the presence of triethylamine in acetonitri le affords a range of neutral complexes, encompassing both tetrahedral and square-planar metal geometries, of differing nuclearities. In addition to t he chemical and physical properties of the ligands and complexes reported, single crystal analyses were employed for geometric analysis in two ligand derivatives: the first, a mononuclear distorted tetrahedral racemic nickel( II) complex; the second, a dinickel heterochiral complex.