Reactivity of hydroxo complexes of palladium(II) towards nitriles: formation of carboxamide and imino ether derivatives of palladium(II)

The binuclear hydroxo complexes [Pd-2(C,N)(2)(mu-OH)(2)] [C,N = 2-(dimethyl aminomethyl)phenyl (dmba) or 2-(phenylazo)phenyl (az)] have been prepared b y addition of 2 equivalents of NBu4OH to the corresponding di-mu-acetate co mplexes in acetone. The reactions of both hydroxo complexes with a number o f nitriles, RCN, led to the formation of the carboxamide complexes [Pd-2(C, N)(2)(mu-NHC(R)O)(2)] (R = Me, Ph or CH2=CH) as well as the succinonitrile derivatives [(C,N)Pd{NHC(O)CH2CH2C(O)NH}Pd(C,N)]. The complexes [Pd-2(C,N)( 2)(mu-NHC(Me)O)(2)] can also be prepared by reaction of [Pd-2(C,N)(2)(mu-OH )(2)] with acetamide. The hydroxo complex [Pd-2(C6F5)(4)(mu-OH)(2)](2-) rea cted with nitriles in methanol or ethanol to give the imino ether complexes [Pd(C6F5)(2){NH=C(OR')R}(2)] (R = Ph, R' = Me or Et; R = Me, R' = Me or Et ) which in acetone solution are present as mixtures of EE, EZ and ZZ isomer s. Similar reactions with 2-cyanopyridine and succinonitrile gave [Pd(C6F5) (2){NC5H4C(OR')NH-2}] and [Pd(C6F5)(2){NHC(OR')CH2CH2NH(OR')}] (R' = Me or Et) and the reaction with 2-cyanopyridine in acetone yielded [Pd(C6F5)(2){N C5H4C(=O)NH-2}]. The crystal structures of [Pd-2(dmba)(2)(mu-NHC(Ph)O)(2)] and [Pd(C6F5)(2){NH=C(OMe)Me}(2)] have been determined by single-crystal X- ray diffraction.