Synthesis, structural characterisations, NMR spectroscopy, Hirshfeld surface analysis and electrochemical study of a new organic cyclohexaphosphate, (C6H7FN)4(Li)2(P6O18) (H2O)6

Abstract

(C6H7FN)4(Li)2(P6O18) (H2O)6(I), a new organic cyclohexaphosphate, has been synthesized and grown at room temperature by an acid/base reaction between H6P6O18 and 2-fluoroaniline as an organic template. The crystal structure of (I) was solved by single crystal X-ray diffraction analysis and it was found that the material belongs to triclinic system with space group P-1 and refined R-factor of 0.0520. Adjacent P6O18 rings are connected via corner-sharing by LiO4 tetrahedra, generating anionic [Li2P6O18·H2O]4- layers parallel to the (a, b) plane. The 2-fluoro-anilinium cations are inserted in the interlayer space and interact with the inorganic framework through NH⋯O and OH⋯O hydrogen-bonding interactions. Additional stabilization is provided by strong NH⋯F and weak CH⋯O hydrogen bonds. Hirshfeld surface analysis reveals the nature of intermolecular contacts of the title compound and their enrichment ratio reveals if they are over-represented. The crystal packing is a combination of strong electrostatic attractive interactions and of weaker hydrophobic contacts. The title compound was further characterized by FT-IR and NMR spectroscopies. Crystal symmetry is confirmed by 31P magic angle spinning NMR and the vibrational absorption bands were identified by infrared spectroscopy. Electrical conductivity was studied using impedance spectroscopy and results showed that the conductivity at 150 °C was equal to 4.93 × 10−4 S cm−1. It is therefore concluded that (C6H7FN)4(Li)2(P6O18) (H2O)6 can be further used in lithium batteries.