Effects of structures and concentrations of mono- and bis-aryliminodimagnesium on the reactions with nitrobenzenes. Formation of azoxy and azo products assisted by aggregated excess of magnesium reagent

The relative yields of azoxy- and azo-type products in the reactions of aryliminodimagnesium [ArN(MgBr)2 (IDMg)] with nitrobenzene were greatly affected by changes in the molar concentration in tetrahydrofuran, addition of hexamethylphosphoramide to the reagent solution and the structures of mono- and bis-IDMg reagents. All the modes of variation of the product distribution, including extreme cases, were roughly but systematically related to a series of qualitative degrees of aggregation of IDMg. The role of aggregation is ascribed to the assistance of excess reagent molecules in the product formation process in the reaction. From the present and previous results and discussion on the reactions of IDMg and RMgBr, the IDMg aggregation is concluded to be an essential modification factor for useful reactions of the NMg (and also CMg) reagents having a suitable efficiency of single electron transfer.