Volatility studies of metal chelates. V. Stability and volatility of transition metal chelates of tetradentate Schiff bases

Abstract

A study of the effect of substituent groups on the thermal stability and volatility of 15 tetradentate β-keto enamines and various copper(II), nickel(II), palladium(II), cobalt(II), and oxovanadium(IV) derivatives has been made by employing simultaneous thermogravimetry and differential thermal analysis. The majority of these chelates are stable at temperatures above 300°C although volatilities are significantly lower than for the corresponding β-diketonates. Trends in the volatilities of the copper(II), nickel(II), palladium(II) and oxovanadium(IV) chelates are rationalized in terms of substituent-group effects on the polarity and intermolecular Lewis acid-base interactions. The distinctive role of the metal ion in controlling chelate volatility is also discussed.