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

Abstract

The complexes 13,14-([X]benzo)-3-(p-[Y]benzoyl)-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradeca-l,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 l/γ max of π→π ⋆ 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 0.047V for B series). The structure of the copper(II) complex (orthorhombic, C2221, a= 8.0994(11), b= 8.3187(10), c= 24.561(5)A, α(=β=γ)= 90.0°, Z= 4, R 1= 0.0474 and wR 2= 0.1219) was characterized using single crystal X-ray diffraction method.