Comparative studies on copper(I) complexes: synthesis, X-ray crystallography and electrochemical properties of [CuI(dafone)nX] complexes (dafone=4,5-diaza-fluoren-9-one, X=Br, I, SCN)

The synthesis, X-ray structures and electrochemical properties of stable five-coordinate, trigonal-bipyramidal CuI complexes of dafone (4,5-diaza-fluoren-9-one) [Cu(dafone)2X] with X=Br (1) or I (2) as ancillary ligands are discussed. The thiocyanate-bridged polymeric CuI complex of dafone, [Cu(dafone)(SCN)]n (3), forms two-dimensional sheets in the crystal, held together by weak interactions involving the dafone ketone group, while the phenanthroline complex, [Cu(phen)(SCN)]n (4), a zigzag arrangement of the phen ligands leads to interchain π-stacking within the lattice. The electrochemical studies reveal that dafone stabilizes the CuI oxidation state more efficiently than phen due to its better π-acceptor ability as indicated by more positive redox potentials for the CuI/CuII couple.