Solution structures of dimeric methylpyrazolyl and indazolyl dimethyl-derivatives of boron, gallium, and indium from 1H nuclear magnetic resonance data

Trimethylboron and trimethylgallium react with 3-methylpyrazole to yield isomer pairs of dimeric products [Me 2 E(Mepz)] 2 (E = B, Ga; Mepz = 3-methylpyrazolyl), in the approximate ratios 4:3 (E = B) and 9:1 (E = Ga), while trimethylindium gives a single species. Reactions of indazole with trimethylgallium and trimethylindium also yield a single structural isomer of the dimer [Me 2 Eind] 2 (E = Ga, In; ind = indazolyl). Solution structures were interpreted on the basis of 1 H nmr data.