Electron density distribution in bis(guanidinium) disodium hypodiphosphate heptahydrate, (CH₆N₃)₂Na₂(P₂O₆)·7H₂O

X-ray structural analysis of bis(guanidinium) disodium hypodiphosphate heptahydrate, (CH₆N₃)₂Na₂(P₂O₆)·7H₂O revealed close Na⁺...guanidinium [Na...N 3.0366 (6) Å] and water...guanidinium O-H...N [H...N 2.07 Å, O...N 3.0401 (9) Å] contacts, the nature of which is explored with the use of electron density distribution and Hirshfeld surface analysis. The crystal structure is governed by coordination interactions to Na⁺ cations and an extensive network of hydrogen bonds, in which guanidinium cations, hypodiphosphate ions and water molecules are involved. Na⁺ cations are in tetragonal pyramidal or octahedral environment, which was proved by continuous shape measures. From ∇²ρ(r_c) and bond degree values, the character of P-P bonds are classified as shared shell or covalent bond types, whereas P-O bonds are of transit closed shell or polarized covalent types. Despite the lack of a lone electron pair on the N atom and positive charge of the guanidinium cation, the existence of an O-H...N hydrogen bond was confirmed by electron density studies.