Formation of unexpected silicon- and disiloxane-bridged multiferrocenyl derivatives bearing Si-O-CH[double bond, length as m-dash]CH 2 and Si-(CH 2 ) 2 C(CH 3 ) 3 substituents via cleavage of tetrahydrofuran and trapping of its ring fragments

• Published in: Dalton transactions : an international journal of inorganic chemistry 2017-09, Vol.46 (35), p.11584-11597
• Main Authors: Bruña, Sonia, González-Vadillo, Ana Mª, Ferrández, Marta, Perles, Josefina, Montero-Campillo, M Merced, Mó, Otilia, Cuadrado, Isabel
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/C7DT02286G

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, Cl SiCH[double bond, length as m-dash]CH or Cl Si-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(C F ) ] , 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.