Formation of Methylmagnesium or Coordinated Ylide? Competition between Decarboxylation of Acetate and Betaine Ligands in [CH3CO2MgO2CCH2X(CH3)(2)]( ) (where X = NCH3 and S)
George N Khairallah, Ellie Jung Hwa Yoo, Richard AJ O'Hair
ORGANOMETALLICS | AMER CHEMICAL SOC | Published : 2010
Decarboxylation of the ligands in the magnesium cations [CH 3CO2MgO2CCH2X(CH3) 2]+ (where X = NCH3, la; and S, 1b) can give rise to either an organometallic cation [CH3MgO2CCH 2X(CH3)2]+, 2, or a coordinated ylide [CH3CO2MgCH2X(CH3) 2]+, 3. Collision-induced dissociation of a precursor complex in which the acetate ligand was 13C labeled allowed the direct determination of the relative ratio of formation of 2 and 3 via a comparison of the losses of 13CO2 and CO2. For the nitrogen betaine, la, both 2a and 3a are formed, in a ratio of ca 1:3, respectively. In contrast, for the sulfur betaine, lb, the coordinated ylide, 3b, is almost exclusively formed. These striking differences are confirmed b..View full abstract
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