CATALYTIC ACTIVITY OF ASYMMETRIC MONOBENZOYLMONOBENZOTETRAAZACYCLO [14]TETRADECINATONICKEL(II) COMPLEXES: X-RAY CRYSTAL STRUCTURE OF MONO BENZO-2,4,9,11-TETRAMETHYL-1,5,8,12-TETRAAZACYCLO[14]TETRADECINATONICKEL(II)

摘要

The complexes, 3-(RHO-Ymonobcnzoyl)-Xmonobenzo-2,4,9,1 1-tetramethyl-1,5.8.12-tetraazacyclo [14]tctradecinato(2-)nickel(II), Y = CH_3, H, Cl, NO_2 or OCH_3, X = H (A) or NO_2 (B) have been synthesized and characterized. IR spectra of the complexes show intense bands in the region 1641-1647 cm~(-1) attributed to the stretching modes of C=O. Electronic absorption spectra for the A series exhibit pi->pi~* and ligand to metal charge transfer (LMCT) transitions, while for the B series an additional band appears between 440 and 452 nm, which might be due to another charge transfer. ~1H NMR spectra show an anisotropic magnetic effect due to the benzoyl group. Voltammograms of the complexes show two one-electron irreversible oxidation peaks in the range +100 to +800mV and two, three or four reduction peaks between -1200 and -2800mV, depending on substituents. Hammett plots of first and second oxidation potentials for the A scries had slopes of 37 and 54 mV (22 and 39mV for the B series), respectively. In oxidations of rho-Zstyrenes (Z = OCH_3, CH_3, H, F or Cl) catalyzed by the complexes, conversion yields of substrates are appreciably affected by substituents of substrates and complexes. The structure of the precursor complex 1 with X = H and without any attached benzoyl group (orthorhombic, P2_12_12_1, a= 7.923(6), b = 8.429(7), c = 24.18(2)A, Z = 4, R1 =0.0224 and wR2 = 0.0577) was characterized using single-crystal X-ray diffraction methods.