Synthesis, structure and luminescence behaviour of zinc(II) complexes containing hexadentate N-donor Schiff bases

2427-2432Six hexacoordinated zinc(II) complexes of the type [Zn(L)](Y)2 [L = N-(1-pyridin-2-yl-formylidene)-N'-[2-({2-[(1-pyridin-2-ylformylidene)amino]ethyl}amino)ethyl]ethane- 1,2-diamine (pfad), Y = ClO4 (1a), Y = PF6 (1b); L = N-(1-pyridin-2-ylmethylidene)-N'-[2-({2 -I(1-pyridin-2-ylmethylidene)amino)ethyl]amino)ethyl)ethane- 1,2-diamine (pmad), Y = ClO4ˉ (2a), Y= PF6- (2b); L = N-(l-pyridin-2-ylbenzylidene)-N'-[2-({2-[(l-pyridin-2 ylbenzylidene)amino]-ethyl]amino)ethyl]ethane- 1,2-diamine (pbad), Y = ClO4ˉ (3a), Y = PF6- (3b)] have been synthesised and characterized on the basis of microanalytical, spectroscopic and other physicochemical properties. Structural analysis of 3a reveals that zinc(II) adopts a distorted octahedral environment with a ZnN6 chromophore ligated by two pyridine N atoms (N1, N1*), two imine N atoms (N2, N2*) and two amine N atoms (N3, N3*) in cis-trans-cis orientation. Spectral properties show that the other complex ions are iso-structural with the dication in 3a.