Synthesis, structure, and electrochemistry of trans-[CoIII{(BA)2pn}(L)2]ClO4 complexes

Abstract

The structure, spectroscopic, and electrochemical properties of [Co{(BA) 2 pn}(L) 2 ]ClO 4 complexes, where (BA) 2 pn = N,N 0 -bis(benzoylacetone)-1,3-propylenediimine dianion and the two ancillary ligands (L) are pyridine, py (1), and 4-methylpyridine, 4-Mepy (2), have been investigated. These complexes have been characterized by elemental analyses, IR, UV-Vis and 1 H-NMR spectroscopy. The crystal structure of [Co{(BA) 2 pn}(py) 2 ]ClO 4 (1) has been determined by X-ray diffraction. The coordination geometry around cobalt(III) is best described as a distorted octahedron. The electrochemical reduction of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Co III -Co II is electrochemically irreversible, which is accompanied by the dissociation of the axial N(py)-cobalt bonds. This process becomes quasi-reversible upon the addition of excess py ligands. The second reduction step of Co II/I shows reversible behavior and is not influenced by the nature of the axial ligands.

[1,1′-Diphenyl-3,3′-(propane-1,3-diyldinitrilo)dibut-1-enolato]copper(II)

“…For general background, see: Bunce et al (1998); Klement et al (1999); Meghdadi et al (2008); Mikuriya et al (2002); Filomeni et al (2007). For a structure determination of the title compound in space group Cc, see: Sarkar et al (2008).…”

“…H 2 (BA) 2 pn, N,N′-bis(benzoylacetone)-1,3-propylenediimine was prepared according to the literature [Meghdadi et al 2008] by the condensation of of benzoylacetone (0.324 g, 2 mmol) with 1,3-propylenediamine (0.074 g, 1 mmol) in methanol at room temperature. To a solution of H 2 (BA) 2 pn (0.362 g, 1 mmol) in methanol (30 ml) was added with stirring copper(II) acetate monohydrate (0.200 g, 1 mmol).…”