Synthesis, characterization of [{(N-methyl-N-benzyl)amino}methyl]ferrocenes and their cyclopalladated complexes: Crystal structure of σ-Pd[(η5-C5H5)Fe(η5-C5H3CH2N(CH3)CH2C6H4NO2-4)]Cl(PPh3)

Condensation of aminomethylferrocene (1) and substituted benzaldehydes resulted in aldimines 2a–c which followed by reduction with sodium borohydride to give 3a–c. N-methylation of 3a–c with HCHO/NaCNBH3/HOAc led to 4a–c. Treatment of 4a–c with sodium palladium tetrachloride in the presence of sodium acetate afforded cleanly cyclopalladated 5a–c in which configurations consisted of the RNRC, SNSC. The preferable activation of CFerrocenyl–H bond over CPhenyl–H bond was also observed. All compounds 2–5 were characterized by elemental analysis, IR and 1H NMR. In addition, the molecular structure of 5c was confirmed by single crystal X-ray diffraction. The possible mechanism for the formation of 5 was also discussed.