Synthesis and characterization of 7,16‐dinicotinoyl‐ and 7,16‐diisonicotinoyltetraaza[14]annulene and their nickel(II) and copper(II) complexes

The reaction of tetraaza[14]annulene and its complexes with nicotinoyl chloride hydrochloride and/or isonicotinoyl chloride hydrochloride produced the 7,16‐dinicotinoylated and/or 7,16‐diisonicotinoylated corresponding products in satisfactory yields. The mass spectra reveal the molecular ion peaks due to the 7,16‐diacylated products. A strong ir band which is correlated with a C = 0 stretching mode is freshly observed in the 1635–1670 cm−1 region upon the acylation. The electronic spectra for the complexes hardly change upon the acylation, but those for the ligands change slightly. The olefinic proton signals at the 7‐ and 16‐positions disappear on the acylation in 1H‐nmr spectra and the substituted pyridine proton signals are newly observed. The proton nmr results are consistent with those of the carbon‐13 nmr. The spin Hamiltonian parameters for the acylated copper(II) complexes are comparable with those for the copper(II) complex which is not acylated. The copper(II) complexes assume the square‐planar coordinations with an unpaired electron in the dx2−y2 orbital.