engleski

Effect of temperature on dicyclopalladation of 4‐ dimethylaminoazobenzenes

Cyclometallation is one of the simplest and most common methods for creating a metal-carbon (M–C) bond and represents a very mild route for activating strong and unreactive a carbon- hydrogen (C–H) bond with transition metals. Cyclopalladated compounds have been vastly investigated due to their unique chemical and physical properties that, when fully explored, enable them for application ranging from catalysts and active units in sensors to cancer treatment agents.[1] In this regard, particularly interesting are complexes with azobenzenes. Azobenzene and its derivatives readily undergo reaction with Pd(II) convenient precursors to produce single or double cyclopalladated complexes containing one or two metalacycles. Although a number of studies of formation of cyclopalladated azobenzenes have been reported the amount of information on the kinetics and mechanism of cyclopalladation is limited. Our previous study of palladation of azobenzenes by PdCl2(DMF)2 suggest that the dipalladation reaction mechanism in solution consists of four successive steps (Scheme 1): (i) co-ordination of the azobenzene to the palladium via one of azo-nitrogens (ii) intramolecular C–H bond activation leading to the formation of a monopalladated complex (iii) formation of a monopalladated adduct in which the free azo-nitrogen coordinates the second Pd atom ; and (iv) the second intramolecular C–H bond activation producing a dipalladated product. As a continuation of this work herein we report the kinetic study of effect of temperature on the reaction of dicyclopalladation of 4- dimethyaminoazobenzenes.

cyclopalladation ; azobenzenes ; activation parameters

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