Conformational diversity of dichromate dianion

The available experimental structures containing a dichromate dianion were gathered from the ICSD (Inorganic Crystal Structure Database) and CSD (Cambridge Structural Database) databases. The geometrical parameters show considerably wide range in bond lengths and bond angles. The Cr–O–Cr angle varies between 116.2° and 162.1°. The range for the Cr–O(terminal) bond lengths is between 1.469 and 1.777 Å. The respective range for the Cr–O(bridging) is 1.622–1.956 Å. The dichromate dianion shows also propensity to experience phase transitions in the solid state. The variation in the bonding parameters is likely due to combination of weak bonding and intermolecular interactions. The most common point group is C1 for a dichromate dianion in the solid state.