1-Sila-[1]ferrocenophanes, structure and reactivity Ring-opening by reactions with boron halides

Article abstract of DOI:10.1016/S0022-328X(03)00780-0

1-Sila-[1]ferrocenophanes (1-5) were studied with respect to their NMR spectroscopic parameters, in particular the coupling constants involving the carbon atom C(1) [¹ J (¹³ C(1),¹³C(2,5)), ¹ J (²⁹Si, ¹³C(1)) and ¹ J (⁵⁷Fe,¹³C)]. The disiloxane 6, containing two 1-sila-[1]ferrocenophane units, possesses a linear Si-O-Si group, as shown by X-ray structural analysis, being different from the bent structure of the same compound that has been reported in the literature. Ring-opening reactions of the complexes 2-5 with some boron halides (PhBCl₂, BCl₃, BBr₃ and BI₃) gave the ferrocene derivatives 7-12, in which the cyclopentadienyl rings bear silyl and boryl groups, respectively. Two of these complexes (9a and 10) were treated with lithium diethylamide in a 1:1 molar ratio, and in both cases selective substitution at the boron atom was observed (13, 14). All products were characterised by their ¹H-, ¹¹B-, ¹³C- and ²⁹Si-NMR data.