Inorganic Chemistry, Vol.36, No.23, 5390-5395, 1997
Copper(I) complexes of 3,3'-bridged 2,2'-biquinoline: Synthesis, properties, structure
A series of 3,3'-bridged derivatives of 2,2'-biquinoline have been prepared where the bridge consists of one to four methylene units or a -CH=CH- moiety. The corresponding [CuL2](ClO4) complexes were also prepared and their structures analyzed and confirmed by H-1 NMR. Electronic absorption maxima for the metal-to-ligand transition were found to move to higher energy and oxidation potentials were found to increase as the ligands became more distorted from planarity. An X-ray analysis was carried out for the most distorted system having a 3,3'-tetramethylene bridge (C44H36BCuF4N4: triclinic,
, a = 11.605(2) Angstrom, b = 12.622(3) Angstrom, c = 14.524(3) Angstrom, alpha = 106.05(1)degrees, beta = 109.06(1)degrees, gamma = 105.37(1)degrees, V = 1778 Angstrom(3), Z = 2). A wide variation in Cu-N bond lengths, 1.98-2.23 Angstrom, was observed, and the two more weakly complexed quinolines were seen to be arranged in an almost parallel fashion. Ligand exchange studies with neocuproine indicated that the strength of Cu(I) binding depends on the planarity of the system as well as the cisoid disposition of the quinoline nitrogens.