Short syntheses of rigid acyclic or macrocyclic poly-imine ligands and their use in Ru(II), Fe(III), and alkali metal complexation

Abstract

Lipophilic derivatives of 2,6-bis(3-pyrazolyl)pyridine and 1,3-bis (3-pyrazolyl)benzene were obtained in acceptable yields by Stork reactions and transformed by N-alkylations into three pentadentates, three bis(bidentates), and one macrocyclic octadentate ligand. The parent bis(pyrazolyl) pyridine constituted a terpyridine analogue and readily formed a Ru(II) complex. By comparison of 1 H nuclear magnetic resonance patterns, it was found that the alkylations in the bis(pyrazolyl)pyridine series conferred an anti,anti conformation of the imino nitrogens. The pentadentates were then able to extract alkali metal ions into CHCl 3 with only modest strength and selectivity, but the preferred extraction of Li + by one of these was notable. By variation of the reaction conditions, a tri-iron(III) and a di-iron(III) complex were obtained from a bis(bidentate).