Selective and Stepwise Bromodemethylation of the Silyl Ligand in Iron(II) Silyl Complexes with Boron Tribromide

Abstract

Treatment of Cp*(CO)2FeSiMe2R (Cp* = C5Me5, R = Me and Ph) with 1 equiv of BBr3 at room temperature afforded Cp*(CO)2FeSiBrMeR (R = Me and Ph) and MeBBr2 in high yields via bromodemethylation of the silyl ligand. Cp*(CO)2FeSiBrMeR (R = Me and Ph) was further converted to Cp*(CO)2FeSiBr2R (R = Me and Ph) quantitatively on addition of another equivalent of BBr3 and heating. Treatment of Cp*(CO)2FeSiMe2SiMe3 with 1 equiv of BBr3 at room temperature led to selective bromodemethylation at the α-silicon atom to produce Cp*(CO)2FeSiBrMeSiMe3, which was also converted to Cp*(CO)2FeSiBr2SiMe3 on heating with another equivalent of BBr3 at 40 °C in quantitative yield. The solid-state structure of Cp*(CO)2FeSiBr2SiMe3 was confirmed by X-ray crystal structure determination.