Hexakis(3-chloro-2-methylanilinium) cyclohexaphosphate dihydrate

In the organic/inorganic salt hydrate, 6C7H9ClN+·P6O18 6−·2H2O, the cyclohexaphosphate anion resides on an inversion centre. The asymmetric unit consists of three cations, one half-anion and a water molecule. In the crystal, the water molecules and the [P6O18]6− anions are linked by O—H⋯O hydrogen bonds, generating infinite layers parallel to the ab plane. These layers are interconnected by the organic cations through N—H⋯O hydrogen bonds.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2652).

Comment
The interest of hybrid organic-inorganic materials has been continuously growing because of their potential applications in several fields (catalysis, biomoleculaire sciences and nonlinear optics) (Shi et al., 2000, Yokotani et al.,1989. Interest of these compounds stems from the intriguing possibility of combining the features of both inorganic and organic systems within a single material (Koo et al., 2004, Xiao et al., 2005. 113.6 (4)° show that the P 6 O 18 ring is significantly distorted from the ideal value 120°. Nevertheless, this distortion is comparatively less important than that observed in Cs 6 P 6 O 18 ·6H 2 O, which shows the greatest distortion for the same angles, ranging between 93.2 and 145.5° (Averbuch-Pouchot & Durif, 1991).
The three crystallography distinct cations involved in this structure exhibit C-C and N-C and C-Cl distances in the range usually found in other molecule analogues such as 4-chloro-2-methylaniline (Fábry et al., 2002). The C-C-C and C-C-N angles are similar to those expected for sp2 hybridization. These groups are almost planar with an average deviation of 0.0018. The mean geometric features of the hydrogen bonds show multiple kinds of hydrogen bonds. The first one involves O-H···O contacts, with O···O distances ranging from 2.813 (4) to 2.934 (4) Å, link between the phosphoric rings which form a bidimensional anionic framework, parallel to the ab plane (Fig. 2). While the second one includes N-H···O contacts, involving weak links since the N···O distances range from 2.705 (4) to 3.079 (4) Å, assuring the cohesion of the network. In addition, some H phenyl atoms also form weak C-H···O(N) interactions with the C···O(N)separations of 2.872 (5)-3.316 (5) Å. All these hydrogen bonds, Van Der Waals, and electrostatic interactions between organic cations and cyclohexaphosphate anions increase the structure stability in the title compound.

Experimental
Crystals of the title compound were synthesized by neutralization of an acidic aqueous solution of H 6 P 6 O 18 (10 ml, 3.5 mmol) by adding dropwise a solution of 3-chloro-2-methylaniline (21 mmol in 20 ml of ethanol). The resulting solution is then kept at room temperature for several days to give colourless crystals of the title compound which are stable under supplementary materials normal conditions of temperature and humidity. The cyclohexaphosphoric acid used in this reaction was produced from an aqueous solution of Li 6 P 6 O 18 (Schulke et al., 1985) passed through an ion exchange resin (Amberlite IR120)

Refinement
Hydrogen atoms of the aromatic and methyl groups were placed at calculated positions with C-H = 0.93 and 0.96 Å, respectively and allowed to ride with U iso (H) = 1.5 U eq (C). H atoms on water molecules and the coordinates of the hydrogen atoms at the NH 3 groups were located in Fourier difference maps and were refined freely simultaneously with individual U iso values.   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.