A Tetra-amido-Protected Ge5-Spiropentadiene.

The first isolable Ge5-spiropentadiene 1 was synthesized via the reduction of (iPr3Si)2NGeCl (3) with potassium. The crystal structure of 1 reveals a spirocyclic Ge5 skeleton containing two Ge-Ge double bonds (avg. 2.34 Å), which are fettered in two Ge3 rings with a dihedral angle of 70.193°. The DFT calculations and orbital analysis show that the σ-delocalization of the Ge5 skeleton and the 2π-delocalized aromatic Ge3 rings enhance the stability of molecule 1.