Synthesis and spectroscopic properties for six 7,16‐dibenzoylated tetraaza[14]annulene nickel(II) complexes

Abstract

AbstractThe condensation reaction between tetraaza[14]annulene nickel(II) complex and a series of para‐substituted benzoyl chlorides gave the corresponding 7,16‐dibenzoylated products in 53–98% yields. The mass spectra exhibit molecular ion peaks ascribed to the 7,16‐dibenzoylated products. The intense ir band due to the CO stretching mode in these nickel(II) complexes is present in the 1650–1658 cm−1 range upon the benzoylation. Even though the ligand moiety of these six complexes is changed by benzoylation, the electronic spectra hardly vary. These nickel(II) complexes assume roughly the square‐planar coordinations as judged by the ligand‐field transition bands. The olefinic proton peaks at the 7‐ and 16‐positions vanish on benzoylation in the proton nmr spectra and the proton signals of the para‐substituted benzoyl groups are observed in the 2.4–8.4 ppm region. The results of the carbon‐13 nmr spectra are compatible with those for the proton nmr spectra.