Coordination polymers containing ferrocene backbone. Synthesis, structure and electrochemistry.

The reaction of 1,1'-ferrocenedicarboxylic acid (LH(2)) with bis(triphenyltin) oxide afforded a molecular heterobimetallic compound [(Ph(3)Sn)(2)L]. 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 LH(2) with trimethyltin hydroxide or bis(tri-n-butyltin) oxide afforded 2D-coordination polymers [(Me(3)Sn)(2)L](n) and [(n-Bu(3)Sn)(2)L](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 [(Ph(3)Sn)(2)L] can be utilized to form coordination polymers. Accordingly the reaction of LH(2) 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.