Crystal structure of bis(2-aminoethyl)amine(di-2-pyridylamine)zinc(II) nitrate and the electronic properties of the copper(II)-doped system

The crystal structure of the title compound [Zn(dien)(bipyam)][NO3]2 has been determined by X-ray crystallographic analysis using photographic data. The complex crystallises in the monoclinic space group P21/c, with a= 12.34(5), b= 16.26(5), c= 9.92(5)A, β= 92.0(5)°, and Z= 4. The zinc(II) ion is five-co-ordinate with a distorted trigonal-bipyramidal stereochemistry, the mean out-of-plane and in-plane Zn–N bond distances being 2.20 and 2.09 A respectively. The e.s.r. and electronic spectra of 1% copper-doped [Zn(dien)(bipyam)][NO3]2 have been determined using polycrystalline samples and single-crystal techniques and the results interpreted to suggest that the stereochemistry of the doped CuN5 chromophore corresponds closely to that observed in the isomorphous [Cu(dien)(bipyam)][NO3]2 complex, rather than to the stereochemistry of the ZnN5 chromophore of the host lattice. Caution is expressed over the use of the Zn–N distances and N–Zn–N angles to describe the stereochemistry of the CuNx chromophore when doped into isomorphous zinc(II) complexes as host lattices and the use of the electronic reflectance spectra of copper(II)-doped zinc(II) complexes as a criterion for comparable stereochemistries is advocated. A comparison of the g and A factors and one-electron orbital energies is made with other very distorted copper(II) systems.