Abstract
Reaction of the imidazolium-substituted iphosphate-diide, (Ipr)(2) C(2) P(2) (IDP), with GeCl(2) ⋅ dioxane and KBArF(24) [(BarF(24) )(-) =tetrakis[(3,5-trifluoromethyl)phenyl]borate)] afforded the dicationic spherical-aromatic nido-cluster [Ge(η(4) -IDP)](2+) ([1](2+) ) (Ipr=1,3-bis(2,6-diisopropylphenyl)imidazolium-2-ylidene). This complex is a rare heavy analogue of the elusive pyramidane [C(η(4) -C(4) H(4) )]. [1](2+) undergoes two reversible one-electron reductions, which yield the radical cation [2]⋅(+) and the neutral Ge(II) species 3. Both [2]⋅(+) and 3 rearrange in solution forming the 2D aromatic and planar imidazolium-substituted digermolide [4](2+) and germole-diide 5, respectively. Both planar species can be oxidized back to [1](2+) using AgSbF(6) . These redox-isomerizations correspond to the fundamental transformation of a 3D aromatic cluster into a 2D aromatic ring compound upon reduction and vice versa. The mechanism of these reactions was elucidated using DFT calculations and cyclic voltammetry experiments.