Experimental and Theoretical Characterization of 4π‐Electron Möbius Aromatic System of a 1,2‐Digermacyclobutadiene†

We present the visualization of the experimental valence electron‐density distribution (EDD) in the isolated 1,2‐digermacyclobutadiene ring system, revealing the unique 4π electron‐delocalization on the four‐membered Ge 2 C 2 ring. A remarkably high Möbius 4π‐electron aromatic character in the Ge 2 C 2 ring can be suggested from theoretical calculations, in sharp contrast to the significant antiaromaticity of the all‐carbon cyclobutadiene ring.