Syntheses, crystal structure and properties of complexes of metallocene-conjugated macrocyclic ligand

Four complexes ([Co(III)2(L1)2(AcO)2(OH)](AcO)(I)24H2O 1, [Fe(III)2(L1)2(AcO)2(OH)](ClO4)2(I) 2, [Co(III)2(L1)2(AcO)2(OH)](ClO4)34H2O 3, and[Fe(III)2(L1)2(AcO)2(OH)](AcO)(ClO4)24H2O 4) (where L1 = N-ferrocenylmethyl-1,4,7-triazacyclononane and L2 = N-ruthenocenylmethyl-1,4,7-triazacyclononane), were synthesised and characterized. Crystal structure of 1 shows that the complexes have a linearly arranged four-core skeleton which can be depicted as Mc-B-M-B′-M-B-Mc (where Mc represents metallocenylCunit, B and B′ represent bridging groups). Electrochemical investigation of these complexes confirms that introduction of the guest metal ions, M, onto the free ligand induces an anodic shift of the redox potential of metallocene and, at the same time, that coordination of ligand to the metal ions causes change in the electrochemical behavior of the guest ion. No interaction is observed between two metallocene components separated by TACN-M (III) fragment, but an interaction between two guest ions is emphasized by the capture of mix-valence species during the course of electrochemical investigation.