New di-ferrocenyl-ethynylpyridinyl triphenylphosphine copper halide complexes and related di-ferricenyl electro-crystallized materials

Three new neutral di-ferrocenyl-ethynylpyridinyl copper complexes, [L (CuCl)(PPh)] (2), [L (CuBr)(PPh)] (3), and [L (CuI)(PPh)] (4) were synthesized from the ferrocenyl-ethynylpyridine ligand (L) (1), the appropriate copper halide CuX (with X = Cl, Br, I) and triphenylphosphine. These neutral complexes were fully characterized by spectroscopic methods and by single crystal X-ray crystallography. Cyclic voltammetry in dichloroethane revealed chemically reversible ferrocenyl oxidation signals followed by characteristic "stripping reduction peaks" showing evidence for oxidation-product electro-crystallization. Scanning electron microscopy confirmed spontaneous formation of crystalline oxidation products with three distinct morphologies for X = Cl, Br, I. Energy dispersive X-ray elemental analysis data show Fe:P ratios of 1:2.0, 1:2.1 and 1:2.1 for electro-crystallization products of complexes 2, 3, and 4, respectively, indicating the presence of two [PF ] anions in the vicinity of the dioxidized complexes, and suggesting product formulae [2][PF] , [3][PF] and [4][PF].