Pentamethylcyclopentadienyl Halfsandwich Complexes of Rhodium and Iridium Containing l,l'-Ferrocene Dichalcogenido Ligands

A series o f 12 bimetallic complexes Cp*M(L)[(EC5H4)2Fe] (M(L) = Rh(PM e3), Ir(PMe3), Ir(PPh3) and Ir(CN'Bu); E = S, Se, Te) has been synthesized from the dichlorides Cp*M(L)Cl2. The new compounds have been characterized by their 'H, 13C and 31P N M R spectra in solu­ tion. The mass spectra indicate that the two-electron ligand L is preferentially eliminated upon electron-impact. Oxidation by AgBF4 to give ferrocenium-type cations also occurs readily. An X-ray structure analysis o f Cp*Rh(PMe3)[(SC5H4)2Fe] ( l a ) confirms the presence o f a 1,l'-ferrocene dithiolate ligand with parallel and ecliptic cyclopentadienyl rings. The long Rh -Fe (430.4(1) pm) distance rules out any direct interaction between the rhodium center and the iron in the cavity o f the ferrocene sandwich.