Coordination polymers containing ferrocene backbone. Synthesis, structure and electrochemistry

Abstract

The reaction of 1,1′-ferrocenedicarboxylic acid (LH₂) with bis(triphenyltin) oxide afforded a molecular heterobimetallic compound [(Ph₃Sn)₂L]. In the latter the two carboxylate units of [L]^2- are involved in an anisobidentate chelating coordination mode to two triphenyl tin units. The reaction of LH₂ with trimethyltin hydroxide or bis(tri-n-butyltin) oxide afforded 2D-coordination polymers [(Me₃Sn)₂L]_n and [(n-Bu₃Sn)₂L]_n which are formed as a result of anisobidentate bridging coordination action of the two carboxylate units of [L]^2-. Interestingly the 2D-coordination polymers contain 24-membered macrocycles each of which is comprised of four trialkyl tin units. The coordination unsaturation of [(Ph₃Sn)₂L] can be utilized to form coordination polymers. Accordingly the reaction of LH₂ with bis(triphenyltin) oxide in the presence of ditopic nitrogen ligands such as 4,4′-bipyridine, 4,4′-trimethylenebipyridine or 4,4′-vinylenebipyridine afforded one-dimensional coordination polymers which contain in their backbone three distinct structural components viz., two triorganotin units, a ferrocenyl unit and a bridging nitrogen ligand unit. The coordination polymers, however, do not retain their structural integrity in solution and fall apart to their monomeric units. Electrochemical studies on these hybrid orgaonotin/ferrocene systems reveal that most of them exhibit a single quasi-reversible oxidation peak.