Formation of unexpected silicon- and disiloxane-bridged multiferrocenyl derivatives bearing Si-O-CH[double bond, length as m-dash]CH and Si-(CH)C(CH) substituents via cleavage of tetrahydrofuran and trapping of its ring fragments.

The formation of a family of silicon- and siloxane-bridged multiferrocenyl derivatives carrying different functional groups attached to silicon, including Fc(CH)C(CH)SiCH[double bond, length as m-dash]CH (5), Fc(CH[double bond, length as m-dash]CH-O)SiCH[double bond, length as m-dash]CH (6), Fc(OH)SiCH[double bond, length as m-dash]CH (7), Fc(CH[double bond, length as m-dash]CH-O)Si-O-Si(O-CH[double bond, length as m-dash]CH)Fc (8) and Fc(CH[double bond, length as m-dash]CH-O)Si-O-SiFc (9) is described. Silyl vinyl ether molecules 6, 8 and 9 and the heteroleptic vinylsilane 5 resulted from the competing metathesis reaction of lithioferrocene (FcLi), CH[double bond, length as m-dash]CH-OLi or (CH)C(CH)Li with the corresponding multifunctional chlorosilane, ClSiCH[double bond, length as m-dash]CH or ClSi-O-SiCl. The last two organolithium species have been likely formed in situ by fragmentation of the tetrahydrofuran solvent. Diferrocenylvinyloxyvinylsilane 6 is noteworthy since it represents a rare example of a redox-active silyl mononomer in which two different C[double bond, length as m-dash]C polymerisable groups are directly connected to silicon. The molecular structures of the silicon-containing multiferrocenyl species 5, 6, 8 and 9 have been investigated by single-crystal X-ray diffraction studies, demonstrating the capture and storage processes of two ring fragments resulting from the cleavage of cyclic THF in redox-active and stable crystalline organometallic compounds. From electrochemical studies we found that by changing the anion of the supporting electrolyte from [PF] to [B(CF)], the redox behaviour of tetrametallic disiloxane 8 can be switched from a poorly resolved multistep redox process to four consecutive well-separated one-electron oxidations, corresponding to the sequential oxidation of the four ferrocenyl moieties.