Tris(2-carbamoylguanidinium) hydrogen fluorophosphonate fluorophosphonate monohydrate

The title structure, 3C2H7N4O+·HFPO3 −·FPO3 2−·H2O, contains three independent 2-carbamoylguanidinium cations, one fluorophosphonate, one hydrogen fluorophosphonate and one water molecule. There are three different layers in the structure that are nearly perpendicular to the c axis. Each layer contains a cation and the layers differ by the respective presence of the water molecule, the hydrogen fluorophosphonate and fluorophosphonate anions. N—H⋯O hydrogen bonds between the guanylurea molecules that interconnect the molecules within each layer are strong. The layers are interconnected by strong and weak O—H⋯O hydrogen bonds between the anions and water molecules, respectively. Interestingly, the configuration of the layers is quite similar to that observed in 2-carbamoylguanidinium hydrogen fluorophosphonate [Fábry et al. (2012). Acta Cryst. C68, o76–o83]. There is also present a N—H⋯F hydrogen bond in the structure which occurs quite rarely.

The title structure, 3C 2 H 7 N 4 O + ÁHFPO 3 À ÁFPO 3 2À ÁH 2 O, contains three independent 2-carbamoylguanidinium cations, one fluorophosphonate, one hydrogen fluorophosphonate and one water molecule. There are three different layers in the structure that are nearly perpendicular to the c axis. Each layer contains a cation and the layers differ by the respective presence of the water molecule, the hydrogen fluorophosphonate and fluorophosphonate anions. N-HÁ Á ÁO hydrogen bonds between the guanylurea molecules that interconnect the molecules within each layer are strong. The layers are interconnected by strong and weak O-HÁ Á ÁO hydrogen bonds between the anions and water molecules, respectively. Interestingly, the configuration of the layers is quite similar to that observed in 2-carbamoylguanidinium hydrogen fluorophosphonate [Fá bry et al. (2012). Acta Cryst. C68, o76-o83]. There is also present a N-HÁ Á ÁF hydrogen bond in the structure which occurs quite rarely.
In order to extend the study of the system guanylurea -fluorophosphonate there have been carried out experiments on the crystal growth from the solutions of different molar ratios of the 2-carbamoylguanidinium cation and the fluorophosphonate. amine H atoms are involved in the hydrogen bonds (Tab. 2) with H···O(acceptor) spanning the range 1.93 -~2.40 Å. This means that these hydrogen bonds are considered as the strong and weak hydrogen bonds (Desiraju & Steiner, 1999).
The title structure is rather unusual for presence of a rare N-H···F hydrogen bond (Dunitz & Taylor, 1997;Krupková et al., 2002) where F belongs to the hydrogen fluorophosphonate (Fig. 5)

Experimental
The structures were prepared by neutralization of stoichiometric amounts of guanylurea hydroxide and H 2 PO 3 F. Guanylurea hydroxide was prepared from guanylurea hydrochloride hemihydrate by an exchange reaction on anex.
Guanylurea chloride hemihydrate has been described at the beginning of the 20 -th century (Ostrogovich, 1911) and thoroughly characterized by Scoponi et al. (1991). It was prepared by acid hydrolysis of cyanoguanidine according to Fig.   8. Diluted water solution (100 ml of water to every 0.1 mol of cyanoguanidine) of equimolar ratios of cyanoguanidine (99%, Sigma-Aldrich) and hydrochloric acid (p.a., Lachema) was gradually heated. After about 45 minutes, when the reaction mixture started boiling, the originally colourless mixture suddenly became greyish and cloudy for a while and then an exothermal process occurred. This process was accompanied by very intense boiling of the reaction mixture. The heating was immediately interrupted and the reaction mixture was placed on a cold magnetic stirrer and it was stirred for another 15 minutes. The liquid which in the meanwhile had turned coulourless again was heated to the boiling point and kept heated for 2 h. Then the excessive water was evaporated under vacuum and a white crystalline product was filtered off. It was purified by recrystallization from water and characterized by powder XRD and found to be identical to the structure JODZOR (Cambridge Crystallographic Database (Allen, 2002;Scoponi et al., 1991). IR spectrum was recorded, too, in order to exclude possibility of contamination of the product by cyanoguanidine. The IR spectrum was in accordance with the compound described by Scoponi et al. (1991), whereas the intense doublet of CNgroup typical for cyanoguanidine was absent.
The solution of H 2 PO 3 F was prepared from solution of (NH 4 ) 2 PO 3 F.H 2 O that passed through the column of catex. (NH 4 ) 2 PO 3 F.H 2 O was prepared by the method described by Schülke & Kayser (1991) and the raw material of (NH 4 ) 2 PO 3 F.H 2 O prepared by this method was recrystallized in order to get rid of contamination of (NH 4) H 2 PO 4 . The volume of the eluted solution of H 2 PO 3 F was about 50 ml in both cases. The solutions were put into the evacuated desiccator over P 4 O 10 . The crystals appeared in one week. The crystals deteriorated quickly on air, possibly because of the mother liquor that remained on the surface of the crystals that could react with air humidity. The crystals were put into the special glass capillaries. For the title structure 0.74 g (NH 4 ) 2 PO 3 F.H 2 O and 1 g of guanylurea hydroxide was applied. It should be added that the experiments in repeated preparation failed and different crystals have been prepared (Fábry et al., 2012b).

Refinement
All the H atoms were discernible in the difference electron density map. The hydroxyl hydrogen H1o11 of the hydrogen fluorophosphonate was refined freely. The coordinates of the atom P1 have not been refined because of the fixing of the origin in the space group of the title structure. There have been applied the following restraints: Water H atoms were restrained to be distant 0.820 (1) Å from the water oxygen Ow while the H1ow-Ow-H2ow angle was restrained to equal to 107.90 (1)°.