Crystal Structure of Cs₂Zn(NO₂)₄: Influence of Steric Crowding on Nitrite Coordination

The crystal structure of Cs-2[ Zn(NO2)(4)] has been determined by X-ray diffraction. Each nitrite ion in the Zn(NO2)(4)(2-) group forms one short [2.080( 3) angstrom] and one long [2.516( 3) angstrom] Zn - O bond, the metal - ligand interaction being intermediate between symmetrical chelation and syn-unidentate nitrito coordination. It seems likely that this unsymmetrical geometry is adopted in order to minimize ligand - ligand repulsions, though density functional theory calculations suggest a very shallow potential energy curve for the complex.