Substitutional location for a vanadyl ion in three water coordinated triaqua(1,10-phenanthroline-k²N,N′) (sulfato-kO)magnesium(II) complex: a rare observation

Abstract

Vanadyl ion substitutes for the central ion, if the doped complex has at least four water molecules. However, the present EPR, XRD, FT-IR and optical absorption studies on vanadyl-doped triaqua(1,10-phenanthroline-k²N,N′)(sulfato-kO)magnesium(II) suggest a substitutional defective nature, which is a rare observation. Single crystal EPR studies in three mutually orthogonal planes indicate two chemically non-equivalent sites with different intensities. However, the lower intensity site could not be analysed due to its weaker intensity and overlap with other sites during crystal rotations. The spin Hamiltonian parameters obtained for the major site are as follows: g _xx =1.973, g _yy =1.972, g _zz =1.930; A _xx =7.15, A _yy =6.77, A _zz =18.92 mT. The direction cosines of principal g and A values suggest that the impurity has entered the lattice substitutionally, which is a very uncommon phenomenon. Admixture coefficients, Fermi contact, dipolar interaction and covalency of metal–ligand bonds have also been evaluated. Optical, FT-IR and powder XRD techniques confirm the structure of the complex.

Keywords:

• EPR
• single crystal
• vanadyl
• spin Hamiltonian
• optical studies
• substitutional

Acknowledgements

P.S.R. thanks DST, Government of India, CSIR and UGC for financial assistance. H.R. thanks the authorities of Sri Manakula Vinayagar Engineering College, Pondicherry, for allowing her to do part-time research.