Paramagnetic Alkyl, Hydride, and Alkene Complexes of the Tpt-Bu,MeCo Moiety

The paramagnetic 15-electron alkyls Tp t - Bu,Me Co(R) (R = Me, Et, n -Bu) have been prepared, and the closely related Tp t - Bu Co(Me) has been structurally characterized. Hydrogenation of Tp t - Bu,Me Co(N 2 ) produced the analogous hydride, Tp t - Bu,Me Co(H), the crystal structure of which has been determined. Reactions of Tp t - Bu,Me Co(N 2 ) with ethylene and propene yielded the corresponding olefin complexes Tp t - Bu,Me Co(C 2 H 3 R) (R = H, Me). Tp t - Bu,Me Co(C 2 H 4 ) has been structurally characterized by X-ray diffraction as well. The alkyls are thermally stable and show no tendency to β-eliminate; upon exposure to CO homolytic cleavage of the Co−C bond is observed rather than migratory insertion.