Ferrocene, 1,1 -dilithio

Silicon-bridged [l,l]metallocenophanes of type 40 in Scheme 14 represent another class of dinuclear compounds with the ligand system (30). The synthesis of the 1,1,12,12-tetramethyl [1,1] silaferrocenophane was reported by two groups only recently. In one procedure, the dilithium salt of dicyclopentadienyldimethylsilane was reacted with ferrous chloride to give a mixture of the metallocenophane with poly(ferrocenyldimethylsilane) (equation 55)124. In the other procedure, this compound was prepared in a multistep synthesis starting from dilithio ferrocene, as shown in equation 56125... 

The lithiation of ferrocene and ruthenocene by tBuLi and nBuLi can be selectively conducted to give predominantly either the mono- or the l,T-dilithio-metallocenes, which may then be converted into the corresponding carbaldehydes using N,N-dimethylformamide [286]. 

The synthesis of atropisomeric biphenylyldiphosphines has been reviewed. The ferrocenyldiphosphine (115) has been prepared by treatment of l,T-dilithio-ferrocene with an aryl methylphenylphosphinite, and isolated in the form of two diastereoisomers which are separable by recrystallisation from ethanol. Metal-lation of mono- and di-(tetramethylcyclopentadienyl)phosphines, followed by treatment with iron(II) chloride, provides a route to the ferrocenyl systems (116)... 

Reaction with methylene 3, 2.5.14.3 Reaction with l.l -dilithio ferrocene 9,... 

Monoferrocenyllithium was prepared by direct metallation of ferrocene with t-BuLi, a procedure that resulted in the formation of traces of l,l -dilithio-ferrocene, explaining the obtention of the interesting diphosphine borane 40 in 3% yield. This has been exploited to prepare bidentate ligands, as detailed below. Other groups prepared other ferrocenyl monophosphines as can be... 

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