SYNTHESES,CHARACTERIZATION AND CRYSTAL STRUCTURE OF TETRAMETHYLDIBENZOTETRAAZA[14]-ANNULENE ZINC(II) COMPLEXES CONTAINING AN AXIAL BASE

Abstract

The complexes of Zn(tmtaa) and Zn(tmtaa)L [H₂tmtaa = tetramethyldibenzotetraaza[14]-annulene; L = triethylamine, pyridine (Py) and p-dimethylaminopyridine (p-N(CH₃)₂Py)] were synthesized and characterized by IR, LTV, mass and NMR spectra as well as DSC measurements. The effects of different axial ligands (L) on the spectral properties of the complexes have been studied. The crystal structure of Zn(tmtaa)N(C₂H₅)3 was determined by X-ray diffraction. The crystal belongs to a monoclinic system and the space group is P2₁/n. The cell parameters are a = 11.134(2)A, b = 17.453(4)Å, c= 13.784(3)Å, ? = 106.19(3)°, Z = 4, R₁, =0.0336 and wR₂= 0.0805 for 4539 independent reflections with I <2σ(I). The zinc(II) is coordinated through four nitrogen atoms of tmtaa and a nitrogen of triethylamine to form a five-coordinate square-pyramidal structure. The average bond length of Zn for the four nitrogens of tmtaa is 2.050(2)Å and for a nitrogen of triethylamine is 2.188(2)Å. The displacement of the zinc to the plane of four nitrogens of tmtaa is 0.563(2)Å.