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

Abstract

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( 13C(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 (PhBCl 2, BCl 3, BBr 3 and BI 3) 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.