Ring-opening addition of hydrogen chloride to monocyclic and spirocyclic [1]ferrocenophanes: a convenient and controlled route to ferrocenylchlorosilanes and germanes

The ring-opening addition of HCl to [1] ferrocenophanes has been shown to p rovide a general method for the preparation of chlorosilanes and germanes w ith ferrocenyl substituents. Reaction of HCl with dimethyl[1]silaferrocenop hane, fcSiMe(2) (1a) [fc = Fe(eta-C5H4)(2)], affords chlorodimethylferrocen ylsilane, FcMe(2)SiCl (3a) [Fc = (eta-C5H4)Fe(eta-C5H5)], in 68% yield. Tri chloroferrocenylsilane, FcSiCl(3) (3b), and chlorodimethylferrocenylgermane , FcMe(2)GeCl (3c), were prepared by an analogous route from ferrocenophane s fcSiCl(2) (Ib) and fcGeMe(2) (1c). Ring-opening addition of HCl to the sp irocyclic [1]ferrocenophane, fcSi(CH2)(3) (4), leads to cleavage of the Si- C bond of the strained ferrocenophane, giving the silacyclobutane FcSiCl(CH 2)(3) (5) in 84% yield. Moreover, treatment of the spirocyclic [1] silaferr ocenophane fc,Si (6) with HCl affords orange crystals of dichlorodiferrocen ylsilane, Fc(2)SiCl(2) (7), in 88% yield. Hydrolysis of 7 in the presence o f triethylamine generated diferrocenylsilanediol, Fc(2)Si(OH)(2) (8), in 90 % yield. A single crystal X-ray diffraction study combined with spectroscop ic identification confirmed that 8 crystallizes in a new bead-and-chain mot if.