Control of N- or C-Bridging Mode in Dimeric Butylmagnesium Silylamides

The simple approach to cleave 4,5-dihydro-2-furyl with lithiated primary amines yields a wide range of N-alkyl-substituted (aminomethyl)silazanes. These are easily deprotonated by dibutylmagnesium, resulting in either magnesium disilylamides or butylmagnesium silylamides upon variation of the stochiometric ratios and reaction temperatures. The obtained dimeric butylmagnesium silylamide compounds [{(CH3)2Si(CH2NC5H10)(NR)}Mg(n-Bu)]2 (R = t-Bu, i-Pr), examined by single-crystal X-ray diffraction analysis, exhibit different bridging modes Mg–El–Mg (El = C, N) according to the steric demand of the ligand. This observation has been studied using theoretical methods.