Metal–metal interaction through CH2–CN bridge: synthesis and characterization of [CpM(L2)NCCH2Fc]PF6 complexes (Fc=ferrocenyl; L=1/2 dppe, PPh3; M=Fe,Ru)

The new complexes [CpM(L2)NCCH2Fc]PF6 (M=Fe 1, Ru 2; Fc=ferrocenyl), have been prepared from reaction of CpM(L2)X and the ligand Fc–CH2CN 3 in methanol and in the presence of NH4PF6. The compounds were characterized by elemental analysis as well as spectroscopic methods. Electrochemical as well as near-IR measurements suggest a weak metal–metal interaction for the Fe(II)–Fe(III) complex. Hush parameters for this mixed-valence complex suggest a class II Robin–Day type with a moderate metal–metal interaction similar to that observed in the related pyridine bridged systems (η5-C5H5)Fe-η5-C5H4–C5H4N–MLn. The unusual electron transfer through a insulating CH2 group is the first such example for an asymmetric binuclear system.