Electron distribution in a stable carbene

Deuterated starting materials enable the synthesis of stable carbene perdeuterio-1,3,4, 5-tetramethylimidazol-2-ylidene. X-ray diffraction and neutral diffraction at 80 and 173 K enable the determination of electron distribution in these molecules. Experimental determination and density functional calculations show the molecule as a true carbene having negligible ylidic character.