Thulium Alkylidene Complexes:  Synthesis, X-ray Structures, and Reactivity

The first thulium alkylidene complexes (2 and 5) were synthesized using a stable dianionic ligand as carbene precursor and were characterized by X-ray diffraction analysis. These complexes were shown to involve metal−carbon double-bond character by their reactivity toward benzophenone. A solid-state dimorphism revealed the participation of a π-overlap between the carbon and the thulium centers in the stabilization of the homoleptic complex 5.