Synthesis and characterization of nickel(II) and copper(II) complexes with non-symmetric tetraaza[14]annulene derivatives. X-ray crystal structure of copper(II) complex

The complexes 13,14-([X]benzo)-3-(p-[Y]benzoyl)-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradeca-1,3,9,11-tetraenato(2-)nickel(II), wherein Y=CH3, H, Cl, NO2 or OCH3, X=CH3 or Cl, have been synthesized and characterized. IR spectra of the benzoylated complexes show intense bands in the regions 1641-1654 cm(-1) attributable to the stretching modes of C=O. Hammett plots of the 1/lambda(max) of pi-->pi* have positive slopes of 0.251 for A series (X=CH3) and 0.233 for B series (X=Cl), respectively, which are quite similar to those based on the NMR resonances of methine protons. The cyclic voltammograms of the complexes show two one-electron irreversible oxidation processes in the potential range of +0.1 to +0.8 V and two, three or four reduction peaks between -1.2 and -2.8 V depending on the substituents. Hammett plots of first and second oxidation potentials are linear with the positive slopes (0.039 and 0.057 V for A series, 0.036 and 0.047 V for B series). The structure of the copper(II) complex (orthorhombic, C222(1), a=8.0994(11), b=8.3187(10), c=24.561(5) Angstrom, alpha(=beta=gamma)=90.0degrees, Z=4, R-1=0.0474 and wR(2)=0.1219) was characterized using single crystal X-ray diffraction method.