[6 + 4] and [4 + 2] Cycloaddition Reactions of Cobaloxime 1,3-Dienyl Complexes and Tropones

1,3-Dien-2-yl(Rpyr)bis(dimethylglyoximato) cobalt(III) complexes (R = H, NMe2) have been shown to participate in cycloaddition reactions with a variety of tropones. In general, tropones that do not contain electron-withdrawing substituents react with dienyl complexes via [6 + 4] cycloaddition and tropones that are substituted with at least one additional electron-withdrawing group react via [4 + 2] cycloaddition. Both types of metal-substituted cycloadducts ([6 + 4] and [4 + 2]) presented here have also been characterized by X-ray crystallography.