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

Abstract

The treatment of 3-(4-chlorophenyl)-4,6-dimethoxyindole with phosphoryl chloride in dimethylformamide generates the regioselective product 3-(4-chlorophenyl)-4,6-dimethoxyindole-7-carbaldehyde. This serves as a valuable ligand precursor and, on reaction with selected di- and tri-amines, yields a number of new acyclic ligands. Treatment of these ligands with selected divalent transition metal acetates in the presence of triethylamine in acetonitrile affords a range of neutral complexes, encompassing both tetrahedral and square-planar metal geometries, of differing nuclearities. In addition to the 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.