Abstract: The ESR spectra of oxovanadium 1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phcnanthroline complexes in glycol water(1:1) solution at various acidity (pH=1-14) have been observed at -100℃. It was found that within the range of 1.4 < pH < 6 phenanthroline can coordinate with oxovanadium to form three complexes and that within the range of 1.0 < pH < 7 3,4,7,8 -tetramethyl-1,10-phenanthroline can coordinate with oxovanadium to form four complexes. Their possible structures were suggested in this paper. When pH-4T is attributed to the complex[VO(H₂O) ₅]²⁺; when pH>11 A=90×10^-4T is attributed to the bidentate chelate of glycol[VO (OCH₂CH₂O)₂]^2- at a ratio of 1:2 of VO(Ⅱ):glycol. The bonding parameters and electronic energy levels were calculated using the spectral parameters measured. It was found that the values of bonding parameters decrease with the increasing of pH values of the solution. The data of electronic energy levels agree fairly well with the experimental, results.

Key words: 1,10-phenanthroline, ESR spectra, Electron spectrum, Crystal field Parameters