SCHIFF-BASES DERIVED FROM AMINOMETHYLFERROCENE AND THEIR CYCLOPALLADATED DERIVATIVES

Synthesis and characterization of novel Schiff bases derived from aminomethylferrocene of general formula: [(eta(5)-C5H5)Fe{(eta(5)C(5)H(4))-CH2-N=CH(C6H4-2-R)}] with R=Cl (1a) and H (1b) are reported. These react with Na-2[PdCl4] and Na(CH3COO). 3H(2)O in methanol at room temperature producing di-mu-chloro-bridged cyclopalladated compounds [Pd{[2-R-C6H3-CH=N-CH2-(eta(5)C(5)H(4))]Fe(eta(5)-C5H5)}( mu-Cl)}], (2a,2b) which contain a sigma(Pd-C(sp)2(phenyl)) bond. However, for (1b), the activation of the sigma(C(sp)2,(ferrocene)-H) bond also takes place giving [Pd{[(eta(5)-C5H3)-CH2-N=CH(C6H5)]Fe(eta(5)-C5H5)}(mu-Cl)](2) (2b'). These dinuclear complexes react with triphenylphosphine (PPh(3)) with cleavage of the mu-Cl bridges, yielding mononuclear derivatives [Pd(C^N)Cl(PPh(3))] (3). The results obtained show the strong influence of the so-called ''endo effect'' in cyclopalladation reactions of N-donor fenocenyl ligands.