Synthesis and characterization of (CHdouble bond; length as m-dashCH)n-bridged (n = 1, 2, 3) heterobimetallic and trimetallic ferrocene–ruthenium complexes

A series of heterobinuclear ferrocene–ruthenium complexes Fc(CHdouble bond; length as m-dashCH)nRuCl(CO)(PMe3)3 (n = 1, 3; n = 2, 12), Fc(CHdouble bond; length as m-dashCH)RuCl(CO)(Py)(PPh3)2 (4), and trimetallic Fc(CHdouble bond; length as m-dashCH)RuCl(CO)(PPh3)2(Py–E–(CHdouble bond; length as m-dashCH)Fc) (6) have been prepared. The length of the molecular rods is extended by successive insertion of CHdouble bond; length as m-dashCH spacers in the bridging ligands or the ancillary ligands. The respective products have been fully characterized and the structures of 3 and 12 have been established by X-ray crystallography. Electrochemical studies have revealed that ethenyl heterobimetallic complexes display two successive one-electron processes, and that intermetallic electronic communication between the two endgroups is attenuated with the increase of the length of the conjugated bridge. The electrochemical behavior of the trimetallic complex reveals strong electronic communication between ruthenium and ferrocene transmitted through the ethenyl bridge, however, it also reveals a very weak interaction between ruthenium and ferrocene transmitted through the (E)–CHdouble bond; length as m-dashCH–Py bridge.