Inorganic Chemistry, Vol.52, No.20, 12012-12022, 2013
New Multi-Ferrocenyl- and Multi-Ferricenyl- Materials via Coordination-Driven Self-Assembly and via Charge-Driven Electro-Crystallization
Three new tetra-ferrocenylethynylpyridinyl copper complexes, L-4(CuI)(4) (3), L-4(CuBr)(2) (4), and L-4(CuCl)(2) (5) have been prepared from the reaction of ferrocenyl-ethynylpyridine (L)(2) with copper halides CuX (with X = I-, Br-, Cl-).The ligand 2 and the complexes 3-5 have been fully characterized by spectroscopic methods. The structures of 2-4 have been confirmed by single-crystal X-ray crystallography. 2 forms a dimer in the crystalline-state through C-H center dot center dot N hydrogen bonds. 4 and 5 are dimers and 3 a tetramer, in all cases linked through Cu-X center dot center dot Cu bridging interactions. Cyclic voltammetry in dichloroethane showed chemically reversible multiferrocenyl oxidation signals with evidence for product electrocrystallization. The oxidation products were isolated by electrodeposition onto a Pt disc electrode and investigated by scanning electron microscopy which confirmed the spontaneous formation of crystalline oxidation products with distinctive morphologies. Energy dispersive X-ray elemental analysis shows the presence of hexafluorophosphate (counterion) with the P:Fe ratio of 1:1, 0.5:1, and 1:1 for the electrocrystallized products 3, 4, and 5, respectively, suggesting the formulas [3](4+)(PF6-)(4), [4](2+)(PF6-)(2), and [5](4+)(PF6-)(4) for the electrocrystallized products.