The intermolecular C−H bond activation of benzene occurs under very mild conditions (room temperature) via a rare stereospecific 1,3-H addition on an unsaturated η2-cyclopropene intermediate generated by a β-H abstraction of CH4 from TpMe2NbMe(c-C3H5)(MeC⋮CMe) to give TpMe2NbPh(c-C3H5)(MeC⋮CMe).