In the Fddd phase of K2C6O6, formally doubly charged (C6O6) 2- rhodizonates orient in layers (Figure ). The anions in this experimental structure are slightly distorted from planarity with a C-C-C-C dihedral angle of 10.94°, an angle in good agreement with our DFT predictions of 12.27°. The K + counterions are situated in-between layers of anions in such a way as to closely coordinate six oxygens. The identification of what is formally (C6O6) 2-and K + ions is confirmed by a topological 47 analysis of the electron density (Table ), which indicate a highly ionic bonding contribution in this material. Our calculations reveal that this phase is a semiconductor with a band gap of 1.2 eV (Figure and S6), a possible underestimation due to the level of theory.