Structural Snapshots of π-Arene Bonding in a Gold Germylene Cation.

Heavier group 14 element cations exhibit a remarkable reactivity that has typically hampered their isolation. For the few available examples, the role of π-arene interactions is crucial to provide kinetic stabilization, but dynamic and structural information on those contacts is yet limited. In this study we have accessed the metalogermylenium cation [(PMe2 ArDipp2 )AuGe(ArDipp2 )Cl]+ (4+ ) (ArDipp2 =C6 H3 -2,6-(C6 H3 -2,6-iPr2 )2 ) that has been structurally characterized with three different non-coordinating counter anions. These studies provide for the first time dynamic information about the conformational rearrangement that characterizes π-arene bonding thorough a series of X-ray diffraction structural snapshots. Computational studies reveal the weak character of the π-arene bonding (ca. 2 kcal mol-1 ) that can be described as the donation from a πC=C bond toward the empty p valence orbital of germanium.