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Thermal and spectroscopic study of dialkyl [alpha-(4-benzeneazoanilino)-N-benzyl]phosphonates and their palladium(II) halide complexes

The mode of thermal decomposition of diethyl and dibutyl esters of [alpha-(4-benzeneazoanilino)-N-benzyl]phosphonic acid and their palladium(II) dihalide adducts, Pd(L)_2X_2 (L=organophosphorus ligand ; X=Cl, Br), as well as cyclopalladated complexes, [Pd(L-H)Cl]_2, have been investigated by thermal (TG, DTA) and spectroscopic (IR, FAB-mass) analyses. Thermal decomposition of the complexes takes place through a multistep process, the first step being a dehalogenation along with deesterification, followed by a complex pyrolysis that leads to a mixture of Pd and P_2O_5. The mass spectrometric data indicate differences in the gas-phase fragmentation pathways between the two types of metal complex and a scheme for their thermal decomposition is proposed. The primary decomposition step in the cyclopalladated complexes is shown to be the loss of the chloride ion. In both derivatives these processes are in competition with the loss of the phosphonate ester group.

thermal study; palladium(II) complexes; cyclopalladated complexes; aminophosphonate complexes

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