Volatility studies of metal chelates. I. Thermal studies of vanadium β-diketonates

Abstract

The complexes of vanadium(111) and oxovanadium(1V) with pentane-2,4-dione; l,l,l-trifluoropentane-2,4-dione; 1,1,1,5,5,5-hexafluoropentane-2,4-dione; l,l,l-trifluoro-5-methylhexane-2,4-dione; l,l,l-trifluoro-5,5-dimethylhexane-2,4-dine 1,1,1,2,2-pentafluoro-6,6-dimethylheptane-3,5-dione and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dione have been prepared. The volatility, thermal and chemical stability of the chelates have been examined by simultaneous differential thermal and thermogravimetric analysis in dynamic atmospheres of nitrogen, air and water-saturated nitrogen and air, in addition to heating under vacuum to temperatures approaching 360°C. The vanadium(111) chelates of the fluorinated β-diketones volatilized with little evidence of decomposition even in air and were stable in the absence of air to 280-320°C. In contrast, the oxovanadium(1V)chelates partly decomposed during volatilization at temperatures as low as 150°C, and completelydecomposed over the temperature range 180-240ºC.