New linked di-germanocenes and di-stannocenes

New bridged di-germanocenes and di-stannocenes 2 have been synthesized from a reaction between (pentamethylcyclopentadienyl)metal chloride and the dilithium salts of the corresponding linked cyclopentadienyl ligands (spacer: phenylene, biphenylene, thiophene) in good yields. These di-metallocenes react easily with catechol giving preferentially the substitution reaction. With iodine or with metal 14 dichloride (M=Ge, Sn), the oxidative products are unstable and rapidly loose the linked cyclopentadienyl ligand. Starting from SnCl2, the ionic half-sandwich compound [Cp*Ge][SnCl3] 8, so obtained, was characterized by X-ray diffraction analysis which reveals a polymeric form in the solid state. The reaction of the di-germanocenes with o-quinone leads to the expected cycloadducts, stable in the case of permethylated compounds. An unusual single electron transfer reaction takes place with [Cp2Fe][BF4] and the transient cation radical rapidly gives [Cp*Ge][BF4]. Mass spectra measurements and electrochemistry study confirm the weak stability of this cationic species.