Tracing environment effects that influence the stability of anion-anion complexes: The case of phosphate-phosphate interactions

► Anion-anion complexes are studied upon environment effects. ► Anion-anion interactions are characterized from the topologies of the electron density and the electrostatic potential. ► The interaction energy is described in terms of hydrogen bond (HB) and non-HB contributions. ► Only non-HB contributions are affected by the charge or the environment. ► Non-HB regions dominate the interaction energy in gas phase but their contribution is balanced in polarizable environment.