PUB - Publikationen an der Universität Bielefeld

Reactions of the lithiated carbanion [(RLi)(2)center dot(RH)] (R = MeN[CH2N(Me)](2)CH, 2,4,6-trimethyl-2,4,6-triazacyclohex-1-yl) with dialkylaluminium and -gallium chlorides lead to the corresponding dialkylaluminium and -gallium compounds (RAlMe2)(2), (RAlEt2)(2) and (RGaEt2)(2). They were characterised by elemental analyses, NMR spectroscopy (H-1, C-13, Al-27) and crystal structure determinations. In the solid state the aluminium and gallium compounds form dimers by intermolecular coordination between the metal acceptor and the nitrogen donor leading to six-membered M2C2N2 rings in chair conformation. As a first test for the synthetic utility of [(RLi)(2)center dot(RH)], nucleophilic aminomethylation of chlorotrimethylsilane was performed to give RSiMe3. Further deprotonation of RSiMe3 with tBuLi occurs at one of the methyl groups bound to the silicon atom leading to RMe2SiCH2Li. Reactions with dimethylaluminium and -gallium chlorides gave RMe2SiCH2AlMe2 and RMe2SiCH2GaMe2. The compounds were characterised by NMR spectroscopy (H-1, C-13, Si-29, Al-27), elemental analyses and single crystal X-ray diffraction. The compounds are monomeric in the solid state with intramolecular M-N bonds (M = Al, Ga) leading to five-membered rings.