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 Cu-I complexes of dafone (4,5-diaza-fluoren-9-one) [Cu(dafone)(2)X] with X = Br (1) or 1 (2) as ancillary ligands are discussed. The thiocyanate-bridged polymeric Cu-I 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 pi-stacking within the lattice. The electrochemical studies reveal that dafone stabilizes the Cu-I oxidation state more efficiently than phen due to its better pi-acceptor ability as indicated by more positive redox potentials for the Cu-I/Cu-II couple. (C) 2002 Published by Elsevier Science B.V.