A new crystal modification of diammonium hydrogen phosphate, (NH4)2(HPO4)

Kunz, P.C.; Wetzel, C.; Spingler, B.

doi:10.1107/S1600536810009839

Volume 66
Part 4
Pages i26-i27
April 2010

Received 8 February 2010
Accepted 16 March 2010
Online 20 March 2010

Key indicators
Single-crystal X-ray study
T = 183 K
Mean (P-O) = 0.002 Å
R = 0.048
wR = 0.158
Data-to-parameter ratio = 29.7
Details

A new crystal modification of diammonium hydrogen phosphate, (NH₄)₂(HPO₄)

Peter C. Kunz,^a ^* Corinna Wetzel ^a and Bernhard Spingler ^b

^aHeirich-Heine-Universität Düsseldorf, Institut für Anorganische Chemie und Strukturchemie I, Universitätsstrasse 1, D-40225 Düsseldorf, Germany, and ^bAnorganisch-Chemisches Institut, Universität Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
Correspondence e-mail: peter.kunz@uni-duesseldorf.de

The addition of hexafluoridophosphate salts (ammonium, silver, thallium or potassium) is usually used to precipitate complex cations from aqueous solutions. It has long been known that PF₆^- is sensitive towards hydrolysis under acidic conditions [Gebala & Jones (1969). J. Inorg. Nucl. Chem. 31, 771-776; Plakhotnyk et al. (2005). J. Fluorine Chem. 126, 27-31]. During the course of our investigation into coinage metal complexes of diphosphine ligands, we used ammonium hexafluoridophosphate in order to crystallize [Ag(diphosphine)₂]PF₆ complexes. From these solutions we always obtained needle-like crystals which turned out to be the title compound, 2NH₄⁺·HPO₄^2-. It was received as the hydrolysis product of NH₄PF₆. The crystals are a new modification of diammonium hydrogen phosphate. In contrast to the previously published polymorph [Khan et al. (1972). Acta Cryst. B28, 2065-2069], Z' of the title compound is 2. In the new modification of the title compound, there are eight molecules of (NH₄)₂(HPO₄) in the unit cell. The structure consists of PO₃OH and NH₄ tetrahedra, held together by O-HO and N-HO hydrogen bonds.

Related literature

For the study of another crystal modification of the title compound, see: Khan et al. (1972). For the hydrolysis of hexafluoridophosphates, see: Akbayeva et al. (2006); Deifel et al. (2008); Fernandez-Galan et al. (1994); Gebala & Jones (1969); Nikitenko et al. (2007); Plakhotnyk et al. (2005).

Experimental

Crystal data

2NH₄⁺·HPO₄^2-
M_r = 132.06
Monoclinic, P 2₁ /c
a = 11.2868 (3) Å
b = 15.3466 (4) Å
c = 6.41894 (19) Å
= 90.795 (3)°
V = 1111.74 (5) Å³
Z = 8
Mo K radiation
= 0.42 mm^-1
T = 183 K
0.44 × 0.17 × 0.11 mm

Data collection

Oxford Xcalibur Ruby CCD diffractometer
Absorption correction: multi-scan CrysAlis PRO (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction, Yarnton, England.]$ ) T_min = 0.891, T_max = 0.955
22537 measured reflections
5384 independent reflections
4400 reflections with I > 2(I)
R_int = 0.033

Refinement

R[F² > 2(F²)] = 0.048
wR(F²) = 0.158
S = 1.21
5384 reflections
181 parameters
16 restraints
H atoms treated by a mixture of independent and constrained refinement
_max = 0.82 e Å^-3
_min = -0.69 e Å^-3

Table 1
Hydrogen-bond geometry (Å, °)

D-HA	D-H	HA	DA	D-HA
O1-H1O7ⁱ	0.78 (4)	1.80 (4)	2.570 (2)	168 (4)
O5-H5O8ⁱⁱ	0.85 (4)	1.79 (4)	2.632 (2)	170 (4)
N11-H11AO4ⁱⁱⁱ	0.86 (2)	1.89 (2)	2.747 (2)	175 (4)
N11-H11BO8ⁱ	0.86 (2)	2.10 (2)	2.951 (2)	171 (3)
N11-H11CO3^iv	0.88 (2)	1.99 (2)	2.852 (3)	169 (3)
N11-H11DO4ⁱ	0.88 (2)	2.01 (2)	2.870 (2)	167 (3)
N12-H12AO6^v	0.87 (2)	1.91 (2)	2.755 (2)	165 (3)
N12-H12BO5^vi	0.88 (2)	2.16 (2)	3.008 (3)	161 (3)
N12-H12CO6ⁱ	0.87 (2)	1.99 (2)	2.827 (2)	161 (3)
N12-H12DO2	0.88 (2)	1.88 (2)	2.754 (2)	175 (3)
N13-H13AO3	0.86 (2)	1.92 (2)	2.773 (2)	172 (3)
N13-H13BO2^vii	0.86 (2)	1.96 (2)	2.822 (2)	175 (3)
N13-H13CO6^v	0.89 (2)	1.95 (2)	2.830 (2)	168 (3)
N13-H13DO2ⁱⁱ	0.86 (2)	1.96 (2)	2.820 (2)	176 (3)
N14-H14AO7	0.87 (2)	1.90 (2)	2.771 (2)	174 (3)
N14-H14BO8^vii	0.86 (2)	2.01 (2)	2.859 (2)	171 (3)
N14-H14CO3^iv	0.86 (2)	1.92 (2)	2.784 (2)	178 (3)
N14-H14DO4	0.89 (2)	1.89 (2)	2.771 (2)	171 (3)
Symmetry codes: (i) -x, -y+1, -z+1; (ii) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iii) $[-x, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) -x, -y+1, -z+2; (v) x+1, y, z+1; (vi) x+1, y, z; (vii) x, y, z+1.

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction, Yarnton, England.]$ ); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BR2137 ).

Acknowledgements

BS thanks the University of Zürich for financial support.

References

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