Copper(I/II) complexes of a bis(tetrathiafulvalene)-2,2′-bipyridine:: synthesis, characterization, magnetic and electrochemical properties

The coordination ability of the electroactive TTF-based chelating ligand 5,5'- bis(4,5-bis(thiomethyl)-4 4'-carbamoyltetrathiafulvalene)-2,2'-bipyridine(L) has been tested with Cu(I) and Cu(II) centres. [(L)(2)Cu-I](PF6), [(L)(2)Cu-II](OTf)(2) and [(L)Cu-II(DMF)(3)](OTf)(2) have been synthesized. A single-crystal X- ray analysis was performed on [(L) CuII(DMF) 3](OTf) 2, showing a distorted octahedral geometry around the Cu(II) centre, and the formation of dimeric units in the solid state through weak coordination in apical position of an amide oxygen atom from a neighbouring complex. Magnetic data show that the paramagnetic metallic centres are isolated, in agreement with the solid-state structure. Electrochemical measurements were performed on the three complexes and in all cases the Cu(I)/Cu(II) and TTF/TTF+center dot/TTF2+ redox processes were observed.