Crystal Structure of [C17H22N2]3[P6O18][H2O]8

*Lamia Khedhiri*

### **Abstract**

[C17H22N2]3[P6O18][H2O]8., a new organic cyclohexaphosphate, was synthesized as single crystals and grown by solution growth method. The crystal structure of the grown product was determined by single crystal X-ray diffraction analysis. The title material crystallized in the monoclinic system of the C2/c space group. The P6O18 6− ring anions and some water molecules form layers spreading around (b, c) planes via O-H…O hydrogen bonds. Between these inorganic layers are anchored organic cations, which establish H-bonds to interconnect the different adjacent layers and so contribute to the cohesion of the three dimensional lattice. The organic and inorganic rings adopt a chair conformation with different geometrical characteristics due to their different size and flexibility. The title compound was further characterized by FT-IR and NMR spectroscopy.

**Keywords:** cyclohexaphosphate, crystal structure, inorganic layers, three dimensional lattice

### **1. Introduction**

Since the preparation and identification of Li6P6O18.6H2O [1], this salt was used as starting reagent to prepare other cyclohexaphosphates. These latters were of great interest in academic and industrial areas over recent years owing to their diversities [2, 3]. Among these compounds, organic cyclohexaphosphates are particularly interesting. Both H-bonds and the organic units are responsible in the organization of such materials as to build inorganic lattices with different features: ribbons [4], two-dimensional lattices [5–7], and three-dimensional lattices [8, 9]. To study the effect on the chemical and structural geometries, we report and discuss in the present work the results of a structural investigation concerning a new organic-cation cyclohexaphosphate [C17H22N2]3[P6O18] [H2O]8. This latter was also characterized by IR and NMR spectroscopy.

The selected organic molecule, 1-(diphenylmethyl)piperazine, is a biogenic diamine, which plays an important role as a deprotonated cation in biological systems [10, 11].

### **2. Chemical preparation**

Based in previous work, the LiH2PO4 [12] and Li6P6O18.6H2O [13] salts were synthesized first. Then, the title compound was prepared by adding cyclohexaphosphoric acid dropwise, produced from Li6P6O18.6H2O through a cation-exchange resin (Amberlite IR 120) into an ethalonic solution of 1-(diphenylmethyl)piperazine. The obtained solution was stirred for few minutes and allowed to a slow solvent evaporation at room temperature until stable crystals of [C17H22N2]3[P6O18][H2O]8 with suitable dimensions were obtained.
