Carbene Complexes of Stannocenes.

Several stannocene carbene complexes, 3a-3g, were synthesized and examined in solution by NMR spectroscopy and in the solid state by single-crystal X-ray diffraction. In this new class of metallocene carbene complexes, coordination of the carbene to the tin atom was found to be comparably weak and mostly due to attractive dispersion forces, as indicated by density functional theory calculations. Furthermore, coordination of the N-heterocyclic carbenes results in a weakening of the Sn-Cp bonds, making these complexes very reactive and short-lived at room temperature.