The title compound crystallizes in the space group Cm((C8)3) with unit cell constants α=8.288 (3)A, b=13.983(7)A, c=11.459(4)A, β=138.32(2) and contains two formula units of Vo(C5H7O2)2.NC5H4- CH3. Intensities of 876 independent reflections were collected with a computer-controlled SYNTEX R3 type four-circle automatic diffractometer using MoKα radiation by \W\/2\W\ scan mode. The variable-scan method was used and the minimum and maximum scan rate were 4 /min and 29.3`/ min respectively. The ratio of background/ scan time being 0.2 was selected. The coordinates of V and two O atoms were derived from the Patterson function first, then the parameters of other atoms were found from successive Fouriers syntheses. Finally, 14 hydrogen atoms were added by theoretical calculation. The blackdiagonal least-squares refinement gave a final discrepancy factor R=0.093 for 799 observed reflections.$TThe structure consists of discrete molecules of VO(acac)2.γ-Pi. Each vanadyl ion VO2+ with V=O bond distance of 1.577(17)A is coordinated to two acacligands in equatorial position and to one γ-picoline molecule in trans- position of the V=O multiple bond. The fact that the active ligands coordinate at the sixth position may escape easily causing the crystal being effloresent in atmosphere implies that the sixth bond is a rather active chemical bond. This phenomenon is in accordance with the observed length 2.45 A of V--N bond in crystal. The stereochemical effects of the formation of the sixth bond on the configuration of the complex as well as on the characteristic features of the coordinated bond type in oxovanadium around vanadium atom have also been discussed.

Key words: CRYSTAL STRUCTURE DETERMINATION, PYRIDINE P, PENTANEDIONE P, MATRICES, OXYGEN COMPOUNDS, VANADIUM COMPLEX, LEAST SQUARE METHODS