Structural elucidation of Cu(II) ion doped in hexaaquozincdiaquobis(malonato)zincate host by EPR spectroscopy Original Research Article

In order to understand the structural behaviour of Cu(II) in a variety of ligand environments, single crystal electron paramagnetic resonance studies of Cu(II) doped in hexaaquazincdiaquabis(malonato)zincate [Zn(H2O)6][Zn(mal)2(H2O)2] are carried out at 300 K. Angular variation of copper hyperfine lines in three orthogonal planes shows the presence of single site, with spin Hamiltonian parameters as g xx=2.034, g yy=2.159, g zz=2.388, A xx=3.39 mT, A yy=4.89 mT and A zz=13.72 mT. The g /A tensor direction cosines are compared with various Zn–O directions in the host lattice, which confirm that Cu(II) enters substitutionally in the lattice. The low value of A zz has been explained by considering admixture of d2x−2ydx2−y2 ground state with d2zdz2 excited state. EPR powder spectra at 300 and 77 K give identical spin Hamiltonian parameters (g∥=2.367, g⊥=2.088, A∥=11.47 mT, A⊥=2.63 mT). IR, UV–vis and powder XRD data confirm the structure and symmetry of the Cu(II) ion in the host lattice.