Two modifications of a KH₂PO₄·HF adduct

The structures of two modifications, (I) and (II), of potassium di­hydrogenphosphate–hydro­fluoric acid (1/1), KH₂PO₄·HF, were determined at 250 and 150 K, and at 292 and 150 K, respectively. Modifications (I) and (II) crystallize from stoichiometric aqueous solutions at 295 (1) and 308 (3) K, respectively. The H atoms were located clearly from the difference Fourier maps in each modification. The two modifications differ mainly in the arrangement of the di­hydrogen­phosphate anions, i.e. (I) contains looped dimeric and tetrameric units of the di­hydrogen­phosphate ions, whereas (II) contains two types of looped tetrameric unit. In addition, both structures contain a very short F—H...O hydrogen bond (2.38–2.40 Å). The K⁺ ions are coordinated by O and F atoms, with similar K...O and K...F distances in both modifications.

S1. Comment

The title compounds were prepared as part of an investigation of trioxofluorophosphates (PO₃F²⁻) and trioxohydrogenfluorophosphates (HPO₃F⁻). Both anions decompose as a result of the hydrolysis reactions H₂O + PO₃F²⁻ → HF + HPO₄²⁻ or H₂O + HPO₃F⁻ → HF + H₂PO₄⁻. Therefore, it was of interest to investigate the formation of products that arise from the decomposition of the fluorophosphate anions, for example, in the reaction between dissolved KH₂PO₄ and HF.

The structures contain sheets of dihydrogenphosphate anions with attached HF molecules, and the anions in each sheet are connected to one another and to HF molecules by hydrogen bonds. Each sheet can be viewed as being composed of two kinds of condensed closed loops of hydrogen-bonded dihydrogenphosphate anions (Figs. 1 and 2), viz. dimers and tetramers in (I), and two kinds of tetramer in (II). The two modifications differ in the number of hydrogenphosphate ions forming these loops, the number of O atoms in the respective loops being four and ten in (I), and six and eight in (II). The loops are centrosymmetric.

The most interesting feature of each modification is a very short F—H···O hydrogen bond. The fact that fluorine is a hydrogen-bond donor is in accordance with the acid strengths of HF (pK_a = 3.20) and of H₃PO₄ (pK_a1 = 2.16; pK_a values from the CRC Handbook of Chemistry and Physics, 1995). The bond length of this F—H···O hydrogen bond is very similar to that observed in the KH₂PO₃·HF adduct (F···O = 2.383 Å; Altenburg & Mootz, 1971), although the F—H···O angle [144.5 (2)°] is not in accordance with those in the present structures and seems to be improbably small for such a short hydrogen bond (Desiraju & Steiner, 1999).

In both modifications, the displacement parameters of the F atoms are substantially larger than those of the O atoms. Therefore, the occupational parameters of atoms F and H3 were refined. The results showed that, within 2 s.u., the occupational parameters of HF in either modification at each temperature were close to 1.0. The dependence of equivalent isotropic parameters, or principal axes, of the displacement parameters on temperature also indicates full occupancy of the F atoms in either modification.

The potassium cation is coordinated irregularly in both modifications. Its coordination polyhedron is formed by seven O atoms and two F atoms in each modification, with shorter distances to the F atoms. In (I), the coordination polyhedron is in the form of a distorted capped tetragonal antiprism with F atoms in cis positions. In (II), the closest atoms (five O atoms and two F atoms) form an irregular pentagonal bipyramid around the K atom, with the F atoms in equatorial positions.

Unexpectedly, although (II) grows at a higher temperature than (I), it has a higher density. Furthermore, the O1···O3 and O2···O3 hydrogen bonds are significantly shorter in (I). No reproducible anomaly indicating the presence of a structural phase transition was observed during differential scanning calorimetry? (DSC) measurements. Signs of decomposition were observed above 360 K for both modifications. The structures determined at low and high temperature are quite similar, thus confirming the results of the DSC measurements. The fractional parameters of the respective non-H atoms are affected in the third decimal place only.

S2. Experimental

To KH₂PO₄ (3.58 g; p.a. Fluka) was added commercial HF (1.38 g of 38 wt%; purum, Spolek pro hutn\'ι_{a chemickou v\' yrobu, Czech Republic) and enough water to dissolve the crystals of KH}2_PO4_{. The initial volume of the mixture was 20 ml. The solution was put in to a desiccator over P}4O₁₀. A few crystals of KH_2PO4_{, several millimeters in size, grew after 30 d. These crystals were hand-picked from the solution, weighed (1.20 g) and checked on a diffractometer. Another batch of crystals of modification (II) of the adduct grew after 14 d from the remaining solution. The shape of these crystals clearly differed from that of the KH}2_PO4 _{crystals. A crystal of this batch was used for the structure determination of modification (II). The preparation was repeated several times with KH}2_PO4 _{(2.38 g) and the same quantities of the other reagents as given above. We found that the growth of a particular modification depended on the ambient temperature. At 295 (1) K, crystals of modification (I) were synthesized, whereas crystallization at 308 (3) K yielded modification (II). The growth of the crystal of modification (II) that was used for the structure determination (above) can be explained by a transitory increase of the temperature in a desiccator. The evolution of diffraction patterns recorded on a diffractometer equipped with a position-sensitive detector showed the gradual appearance of Debye rings, thus indicating that the crystals are unstable when kept in a glass capillary. For this reason, the data collection of modification (I) that followed that of (II) was carried out under a stream of nitrogen gas. If crystals of either modification are left in a desiccator over P}4_O10 _{for several months, the crystals become opaque and are covered with a white powder.}

DSC measurements were carried with a Perkin Elmer DSC7 instrument with the Pyris Software (Perkin Elmer Instruments, 2001) over the temperature range 95–390 K, at a scanning rate of 10 K min⁻¹.

Computing details

Data collection: COLLECT (Nonius, 1997–2000) for KDPHF250I; COLLECT (Nonius BV, 1997-2000) for KDPHF150I, KDPHF292II, KDPHF150II. For all compounds, cell refinement: HKL DENZO SCALEPACK (Otwinowski & Minor, 1997). Data reduction: HKL DENZO and SCALEPACK for KDPHF250I; HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997) for KDPHF150I, KDPHF292II, KDPHF150II. For all compounds, program(s) used to solve structure: SIR97 (Cascarano et al., 1996); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. A view of modification (I) (250 K), projected along the a axis. Displacement ellipsoids are shown at the 30% probability level.
	Fig. 2. A view of modification (II) (292 K), projected along the a axis. Displacement ellipsoids are shown at the 30% probability level.

(KDPHF250I) 'potassium dihydrogenphosphate - hydrofluoric acid adduct (I)'

Crystal data

KH2PO4·HF	F(000) = 312
Mr = 156.09	Dx = 2.176 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 1419 reflections
a = 6.1903 (1) Å	θ = 1.0–30.0°
b = 12.0733 (2) Å	µ = 1.38 mm^−1
c = 7.0741 (1) Å	T = 250 K
β = 115.6700 (8)°	Irregular, colourless
V = 476.52 (1) Å^3	0.50 × 0.47 × 0.35 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1381 independent reflections
Radiation source: fine-focus sealed tube	1318 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
ω scans	θmax = 30.1°, θmin = 3.4°
Absorption correction: multi-scan PLATON (Spek, 2002)	h = −8→8
Tmin = 0.669, Tmax = 0.736	k = −16→16
7968 measured reflections	l = −8→9

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.022	w = 1/[σ^2(Fo^2) + (0.0243P)^2 + 0.1671P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.057	(Δ/σ)max = 0.002
S = 1.11	Δρmax = 0.28 e Å^−3
1381 reflections	Δρmin = −0.50 e Å^−3
77 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.398 (11)
Primary atom site location: structure-invariant direct methods

Special details

Experimental. Glued by epoxy resine; the sample was kept under a stream of dry nitrogen gas.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K	0.85181 (5)	0.86704 (2)	0.11642 (4)	0.02417 (10)
P	0.65486 (5)	0.13985 (2)	0.40733 (4)	0.01475 (10)
O1	0.55300 (15)	0.03632 (7)	0.26045 (13)	0.02227 (18)
O2	0.48366 (15)	0.23861 (7)	0.29023 (14)	0.02397 (19)
O3	0.63859 (16)	0.12101 (6)	0.61182 (13)	0.02077 (18)
O4	0.90418 (14)	0.16322 (7)	0.43052 (13)	0.02207 (19)
F	1.01399 (18)	0.07898 (8)	0.17807 (16)	0.0428 (2)
H1	0.480 (4)	−0.0160 (18)	0.303 (3)	0.047 (5)*
H2	0.546 (4)	0.2848 (18)	0.234 (3)	0.047 (5)*
H3	0.969 (5)	0.111 (2)	0.266 (4)	0.081 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.02135 (15)	0.02922 (16)	0.02017 (15)	−0.00345 (8)	0.00732 (11)	0.00064 (8)
P	0.01686 (15)	0.01367 (15)	0.01484 (16)	−0.00059 (8)	0.00792 (12)	−0.00039 (8)
O1	0.0299 (4)	0.0212 (4)	0.0189 (4)	−0.0085 (3)	0.0136 (3)	−0.0056 (3)
O2	0.0221 (4)	0.0211 (4)	0.0318 (5)	0.0041 (3)	0.0145 (3)	0.0103 (3)
O3	0.0319 (4)	0.0168 (3)	0.0172 (4)	−0.0021 (3)	0.0139 (3)	−0.0018 (3)
O4	0.0176 (4)	0.0243 (4)	0.0249 (4)	−0.0023 (3)	0.0097 (3)	−0.0041 (3)
F	0.0595 (6)	0.0367 (4)	0.0550 (6)	−0.0045 (4)	0.0463 (5)	−0.0083 (4)

Geometric parameters (Å, º)

K—F^i	2.6371 (9)	O1—K^vi	2.9934 (9)
K—F^ii	2.7141 (10)	O1—K^vii	3.2045 (9)
K—O2^iii	2.8880 (9)	O1—H1	0.90 (2)
K—O3^iv	2.9007 (9)	O2—K^viii	2.8881 (9)
K—O4^iv	2.9143 (9)	O2—K^vi	3.0065 (10)
K—O4^v	2.9802 (9)	O2—H2	0.87 (2)
K—O1^vi	2.9934 (9)	O3—K^iv	2.9006 (9)
K—O2^vi	3.0066 (10)	O4—K^iv	2.9143 (9)
K—O1^ii	3.2045 (9)	O4—K^ix	2.9802 (9)
P—O1	1.5723 (8)	F—K^i	2.6370 (9)
P—O2	1.5718 (8)	F—K^vii	2.7140 (10)
P—O3	1.5102 (8)	F—H3	0.88 (3)
P—O4	1.5064 (8)
F^i—K—F^ii	70.90 (3)	F^ii—K—O1^ii	64.65 (2)
F^i—K—O2^iii	144.80 (3)	O2^iii—K—O1^ii	72.45 (2)
F^ii—K—O2^iii	136.22 (3)	O3^iv—K—O1^ii	111.68 (2)
F^i—K—O3^iv	83.51 (3)	O4^iv—K—O1^ii	79.97 (2)
F^ii—K—O3^iv	68.05 (3)	O4^v—K—O1^ii	162.22 (2)
O2^iii—K—O3^iv	123.95 (3)	O1^vi—K—O1^ii	70.05 (2)
F^i—K—O4^iv	135.17 (3)	O2^vi—K—O1^ii	108.68 (2)
F^ii—K—O4^iv	87.83 (3)	O1—P—O2	105.60 (5)
O2^iii—K—O4^iv	76.27 (2)	O1—P—O3	109.83 (5)
O3^iv—K—O4^iv	51.73 (2)	O1—P—O4	108.63 (5)
F^i—K—O4^v	76.57 (3)	O2—P—O3	108.03 (5)
F^ii—K—O4^v	128.78 (3)	O2—P—O4	109.90 (5)
O2^iii—K—O4^v	91.81 (2)	O3—P—O4	114.47 (5)
O3^iv—K—O4^v	69.92 (2)	P—O1—K^vi	102.71 (4)
O4^iv—K—O4^v	88.44 (2)	P—O1—K^vii	126.56 (4)
F^i—K—O1^vi	68.21 (3)	K^vi—O1—K^vii	109.95 (2)
F^ii—K—O1^vi	83.36 (3)	P—O2—K^viii	132.40 (5)
O2^iii—K—O1^vi	90.31 (3)	P—O2—K^vi	102.18 (4)
O3^iv—K—O1^vi	145.23 (2)	K^viii—O2—K^vi	100.34 (3)
O4^iv—K—O1^vi	149.71 (2)	P—O3—K^iv	97.05 (4)
O4^v—K—O1^vi	119.46 (2)	P—O4—K^iv	96.59 (4)
F^i—K—O2^vi	70.88 (3)	P—O4—K^ix	133.42 (5)
F^ii—K—O2^vi	127.43 (3)	K^iv—O4—K^ix	100.36 (3)
O2^iii—K—O2^vi	73.975 (17)	P—O1—H1	116.8 (13)
O3^iv—K—O2^vi	139.23 (2)	P—O2—H2	113.4 (13)
O4^iv—K—O2^vi	144.41 (2)	P—O3—H1^x	132.0 (7)
O4^v—K—O2^vi	73.53 (2)	P—O3—H2^xi	124.9 (7)
O1^vi—K—O2^vi	49.34 (2)	P—O4—H3	116 (1)
F^i—K—O1^ii	121.09 (3)

Symmetry codes: (i) −x+2, −y+1, −z; (ii) x, y+1, z; (iii) −x+1, y+1/2, −z+1/2; (iv) −x+2, −y+1, −z+1; (v) −x+2, y+1/2, −z+1/2; (vi) −x+1, −y+1, −z; (vii) x, y−1, z; (viii) −x+1, y−1/2, −z+1/2; (ix) −x+2, y−1/2, −z+1/2; (x) −x+1, −y, −z+1; (xi) x, −y+1/2, z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
F—H3···O4	0.88 (3)	1.52 (3)	2.3953 (12)	176 (3)
O1—H1···O3^x	0.90 (2)	1.70 (2)	2.5999 (11)	175.5 (19)
O2—H2···O3^xii	0.87 (2)	1.67 (2)	2.5365 (11)	174 (2)

Symmetry codes: (x) −x+1, −y, −z+1; (xii) x, −y+1/2, z−1/2.

(KDPHF150I) 'potassium dihydrogenphosphate - hydrofluoric acid adduct (I)'

Crystal data

KH2PO4·HF	F(000) = 312
Mr = 156.09	Dx = 2.196 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 1412 reflections
a = 6.1624 (1) Å	θ = 1.0–30.0°
b = 12.0744 (2) Å	µ = 1.39 mm^−1
c = 7.0448 (1) Å	T = 150 K
β = 115.7400 (9)°	Irregular shape, colourless
V = 472.17 (1) Å^3	0.50 × 0.47 × 0.35 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1373 independent reflections
Radiation source: fine-focus sealed tube	1322 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ω scans	θmax = 30.0°, θmin = 3.4°
Absorption correction: multi-scan PLATON (Spek, 2002)	h = −8→8
Tmin = 0.662, Tmax = 0.733	k = −16→16
8085 measured reflections	l = −9→9

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.020	w = 1/[σ^2(Fo^2) + (0.0277P)^2 + 0.1281P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.059	(Δ/σ)max = 0.001
S = 1.23	Δρmax = 0.55 e Å^−3
1373 reflections	Δρmin = −0.51 e Å^−3
77 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.165 (7)
Primary atom site location: structure-invariant direct methods

Special details

Experimental. Glued with epoxy resin; the sample was kept under a stream of dry nitrogen gas.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K	0.85237 (4)	0.86720 (2)	0.11552 (4)	0.01492 (10)
P	0.65433 (5)	0.14024 (2)	0.40741 (4)	0.00934 (10)
O1	0.55392 (13)	0.03648 (6)	0.25966 (12)	0.01411 (17)
O2	0.48090 (14)	0.23883 (6)	0.28986 (13)	0.01516 (17)
O3	0.63781 (14)	0.12091 (6)	0.61282 (13)	0.01335 (17)
O4	0.90522 (13)	0.16468 (7)	0.43152 (13)	0.01388 (17)
F	1.01763 (14)	0.07753 (7)	0.18117 (13)	0.02595 (19)
H1	0.479 (3)	−0.0173 (18)	0.302 (3)	0.038 (5)*
H2	0.542 (4)	0.2854 (18)	0.233 (3)	0.039 (5)*
H3	0.973 (4)	0.110 (2)	0.277 (4)	0.063 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.01333 (14)	0.01750 (15)	0.01283 (15)	−0.00208 (7)	0.00464 (10)	0.00047 (7)
P	0.01049 (15)	0.00855 (15)	0.00968 (16)	−0.00030 (8)	0.00504 (12)	−0.00029 (8)
O1	0.0187 (4)	0.0130 (3)	0.0127 (4)	−0.0051 (3)	0.0088 (3)	−0.0034 (3)
O2	0.0142 (3)	0.0133 (4)	0.0199 (4)	0.0025 (3)	0.0092 (3)	0.0064 (3)
O3	0.0193 (4)	0.0109 (3)	0.0117 (4)	−0.0011 (3)	0.0085 (3)	−0.0009 (3)
O4	0.0113 (3)	0.0148 (4)	0.0160 (4)	−0.0015 (3)	0.0064 (3)	−0.0025 (3)
F	0.0360 (4)	0.0219 (4)	0.0336 (4)	−0.0028 (3)	0.0278 (4)	−0.0051 (3)

Geometric parameters (Å, º)

K—F^i	2.6286 (8)	O1—K^vi	2.9764 (8)
K—F^ii	2.7003 (8)	O1—K^vii	3.1959 (8)
K—O2^iii	2.8729 (8)	O1—H1	0.92 (2)
K—O3^iv	2.8864 (8)	O2—K^viii	2.8729 (8)
K—O4^iv	2.9021 (8)	O2—K^vi	2.9864 (9)
K—O4^v	2.9582 (8)	O2—H2	0.86 (2)
K—O1^vi	2.9764 (8)	O3—K^iv	2.8864 (8)
K—O2^vi	2.9864 (9)	O4—K^iv	2.9021 (8)
K—O1^ii	3.1959 (8)	O4—K^ix	2.9582 (8)
P—O1	1.5737 (8)	F—K^i	2.6286 (8)
P—O2	1.5737 (8)	F—K^vii	2.7003 (8)
P—O3	1.5122 (8)	F—H3	0.92 (2)
P—O4	1.5093 (8)
F^i—K—F^ii	71.03 (3)	F^ii—K—O1^ii	64.55 (2)
F^i—K—O2^iii	144.77 (3)	O2^iii—K—O1^ii	72.74 (2)
F^ii—K—O2^iii	136.23 (2)	O3^iv—K—O1^ii	111.62 (2)
F^i—K—O3^iv	83.96 (2)	O4^iv—K—O1^ii	80.09 (2)
F^ii—K—O3^iv	67.59 (2)	O4^v—K—O1^ii	162.28 (2)
O2^iii—K—O3^iv	123.70 (2)	O1^vi—K—O1^ii	69.76 (2)
F^i—K—O4^iv	135.96 (2)	O2^vi—K—O1^ii	109.05 (2)
F^ii—K—O4^iv	87.75 (2)	O1—P—O2	105.79 (5)
O2^iii—K—O4^iv	75.63 (2)	O1—P—O3	109.85 (4)
O3^iv—K—O4^iv	52.06 (2)	O1—P—O4	108.63 (4)
F^i—K—O4^v	77.16 (2)	O2—P—O3	107.92 (4)
F^ii—K—O4^v	128.71 (2)	O2—P—O4	109.86 (4)
O2^iii—K—O4^v	91.53 (2)	O3—P—O4	114.45 (5)
O3^iv—K—O4^v	70.01 (2)	P—O1—K^vi	102.34 (4)
O4^iv—K—O4^v	88.26 (2)	P—O1—K^vii	127.16 (4)
F^i—K—O1^vi	67.92 (2)	K^vi—O1—K^vii	110.24 (2)
F^ii—K—O1^vi	83.91 (2)	P—O2—K^viii	132.58 (4)
O2^iii—K—O1^vi	90.37 (2)	P—O2—K^vi	101.93 (4)
O3^iv—K—O1^vi	145.38 (2)	K^viii—O2—K^vi	100.90 (2)
O4^iv—K—O1^vi	149.43 (2)	P—O3—K^iv	96.93 (4)
O4^v—K—O1^vi	119.64 (2)	P—O4—K^iv	96.36 (4)
F^i—K—O2^vi	70.67 (2)	P—O4—K^ix	133.74 (4)
F^ii—K—O2^vi	128.21 (3)	K^iv—O4—K^ix	100.89 (2)
O2^iii—K—O2^vi	74.131 (16)	K^i—F—K^vii	108.97 (3)
O3^iv—K—O2^vi	138.93 (2)	P—O1—H1	117.0 (12)
O4^iv—K—O2^vi	143.75 (2)	P—O2—H2	113.9 (13)
O4^v—K—O2^vi	73.11 (2)	P—O3—H1^x	132.3 (7)
O1^vi—K—O2^vi	49.79 (2)	P—O3—H2^xi	124.5 (7)
F^i—K—O1^ii	120.43 (2)	P—O4—H3	115.6 (10)

Symmetry codes: (i) −x+2, −y+1, −z; (ii) x, y+1, z; (iii) −x+1, y+1/2, −z+1/2; (iv) −x+2, −y+1, −z+1; (v) −x+2, y+1/2, −z+1/2; (vi) −x+1, −y+1, −z; (vii) x, y−1, z; (viii) −x+1, y−1/2, −z+1/2; (ix) −x+2, y−1/2, −z+1/2; (x) −x+1, −y, −z+1; (xi) x, −y+1/2, z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
F—H3···O4	0.92 (2)	1.48 (2)	2.3998 (10)	178.5 (9)
O1—H1···O3^x	0.92 (2)	1.68 (2)	2.5955 (11)	175.5 (19)
O2—H2···O3^xii	0.86 (2)	1.67 (2)	2.5310 (11)	176 (2)

Symmetry codes: (x) −x+1, −y, −z+1; (xii) x, −y+1/2, z−1/2.

(KDPHF292II) 'potassium dihydrogenphosphate - hydrofluoric acid adduct (II)'

Crystal data

KH2PO4·HF	F(000) = 312
Mr = 156.09	Dx = 2.247 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 5501 reflections
a = 6.5004 (2) Å	θ = 1.0–30.0°
b = 7.6116 (2) Å	µ = 1.43 mm^−1
c = 9.5029 (2) Å	T = 292 K
β = 101.1500 (16)°	Plate, colourless
V = 461.31 (2) Å^3	0.65 × 0.5 × 0.4 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1344 independent reflections
Radiation source: fine-focus sealed tube	1305 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.041
Detector resolution: 9.091 pixels mm^-1	θmax = 30.0°, θmin = 3.2°
ω scans	h = 0→9
Absorption correction: multi-scan SORTAV (Blessing, 1997)	k = −10→10
Tmin = 0.355, Tmax = 0.582	l = −13→13
8372 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.025	w = 1/[σ^2(Fo^2) + (0.048P)^2 + 0.1751P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.071	(Δ/σ)max = 0.001
S = 1.11	Δρmax = 0.53 e Å^−3
1344 reflections	Δρmin = −0.39 e Å^−3
77 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.147 (9)
Primary atom site location: structure-invariant direct methods

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K	0.84452 (5)	0.22735 (4)	0.45543 (4)	0.02959 (13)
P	0.61662 (5)	0.70482 (4)	0.32991 (3)	0.01563 (12)
O1	0.64225 (17)	0.86369 (13)	0.43720 (10)	0.0257 (2)
O2	0.40636 (15)	0.61707 (13)	0.35149 (11)	0.0237 (2)
O3	0.59080 (16)	0.77931 (12)	0.18096 (10)	0.0221 (2)
O4	0.79729 (15)	0.57833 (14)	0.36943 (10)	0.0255 (2)
F	0.96517 (16)	0.47408 (16)	0.18430 (12)	0.0420 (3)
H1	0.632 (3)	0.832 (3)	0.519 (3)	0.043 (6)*
H2	0.405 (4)	0.506 (4)	0.335 (3)	0.059 (7)*
H3	0.898 (4)	0.518 (4)	0.251 (4)	0.077 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.03004 (19)	0.02608 (19)	0.03087 (19)	0.00392 (11)	0.00145 (13)	0.00407 (11)
P	0.02087 (19)	0.01432 (18)	0.01216 (17)	0.00039 (10)	0.00433 (11)	0.00048 (9)
O1	0.0412 (5)	0.0209 (5)	0.0171 (4)	−0.0088 (4)	0.0112 (4)	−0.0045 (3)
O2	0.0241 (4)	0.0176 (5)	0.0310 (5)	−0.0024 (3)	0.0092 (4)	−0.0028 (4)
O3	0.0348 (5)	0.0190 (5)	0.0130 (4)	0.0034 (3)	0.0057 (3)	0.0018 (3)
O4	0.0249 (4)	0.0283 (5)	0.0237 (4)	0.0078 (4)	0.0059 (3)	0.0072 (4)
F	0.0380 (5)	0.0506 (6)	0.0396 (5)	0.0048 (5)	0.0129 (4)	−0.0148 (5)

Geometric parameters (Å, º)

K—F^i	2.6526 (11)	P—O2	1.5699 (10)
K—F^ii	2.7650 (13)	P—O3	1.5038 (10)
K—O4	2.7933 (11)	P—O4	1.5089 (10)
K—O3^iii	2.9026 (11)	O1—K^vii	3.0549 (10)
K—O2^iv	2.9301 (10)	O1—K^v	3.3668 (12)
K—O4^v	2.9800 (11)	O2—K^iv	2.9301 (10)
K—O1^vi	3.0550 (10)	O2—K^viii	3.1672 (11)
K—O2^iii	3.1673 (11)	O3—K^viii	2.9026 (11)
K—O1^v	3.3668 (12)	O4—K^v	2.9800 (11)
K—F	3.4003 (12)	F—K^ix	2.6527 (11)
P—O1	1.5696 (10)	F—K^x	2.7650 (13)
F^i—K—F^ii	84.37 (4)	F^i—K—O1^v	60.92 (3)
F^i—K—O4	142.28 (4)	F^ii—K—O1^v	59.53 (3)
F^ii—K—O4	124.08 (3)	O4—K—O1^v	109.39 (3)
F^i—K—O3^iii	123.57 (3)	O3^iii—K—O1^v	170.65 (3)
F^ii—K—O3^iii	111.63 (3)	O2^iv—K—O1^v	122.16 (3)
O4—K—O3^iii	72.33 (3)	O4^v—K—O1^v	46.48 (3)
F^i—K—O2^iv	80.35 (3)	O1^vi—K—O1^v	102.77 (2)
F^ii—K—O2^iv	159.62 (3)	O2^iii—K—O1^v	121.88 (3)
O4—K—O2^iv	75.74 (3)	F^i—K—F	149.95 (4)
O3^iii—K—O2^iv	67.17 (3)	F^ii—K—F	80.271 (13)
F^i—K—O4^v	75.74 (3)	O4—K—F	43.82 (3)
F^ii—K—O4^v	103.91 (3)	O3^iii—K—F	86.23 (3)
O4—K—O4^v	73.65 (3)	O2^iv—K—F	119.28 (3)
O3^iii—K—O4^v	140.42 (3)	O4^v—K—F	83.06 (3)
O2^iv—K—O4^v	85.36 (3)	O1^vi—K—F	128.12 (3)
F^i—K—O1^vi	65.07 (3)	O2^iii—K—F	66.53 (3)
F^ii—K—O1^vi	64.45 (3)	O1^v—K—F	89.03 (3)
O4—K—O1^vi	145.92 (3)	O1—P—O2	103.22 (6)
O3^iii—K—O1^vi	74.12 (3)	O1—P—O3	107.42 (6)
O2^iv—K—O1^vi	96.67 (3)	O1—P—O4	110.50 (6)
O4^v—K—O1^vi	139.70 (3)	O2—P—O3	109.99 (6)
F^i—K—O2^iii	128.30 (3)	O2—P—O4	110.57 (6)
F^ii—K—O2^iii	64.63 (3)	O3—P—O4	114.50 (6)
O4—K—O2^iii	88.63 (3)	P—O1—H1	112 (2)
O3^iii—K—O2^iii	48.78 (3)	P—O2—H2	112 (2)
O2^iv—K—O2^iii	115.72 (3)	P—O3—H1^xi	127.7 (8)
O4^v—K—O2^iii	148.58 (3)	P—O3—H2^viii	117.1 (9)
O1^vi—K—O2^iii	64.43 (3)	P—O4—H3	116 (1)

Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+2, y−1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1, −y+1, −z+1; (v) −x+2, −y+1, −z+1; (vi) x, y−1, z; (vii) x, y+1, z; (viii) −x+1, y+1/2, −z+1/2; (ix) x, −y+1/2, z−1/2; (x) −x+2, y+1/2, −z+1/2; (xi) x, −y+3/2, z−1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
F—H3···O4	0.90 (3)	1.48 (3)	2.3787 (14)	175 (3)
O1—H1···O3^xii	0.83 (3)	1.82 (3)	2.6386 (14)	168 (3)
O2—H2···O3^iii	0.86 (3)	1.73 (3)	2.5898 (14)	174 (3)

Symmetry codes: (iii) −x+1, y−1/2, −z+1/2; (xii) x, −y+3/2, z+1/2.

(KDPHF150II) 'potassium dihydrogenphosphate - hydrofluoric acid adduct (II)'

Crystal data

KH2PO4·HF	F(000) = 312
Mr = 156.09	Dx = 2.287 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: -P 2ybc	Cell parameters from 4563 reflections
a = 6.4480 (2) Å	θ = 1.0–30.0°
b = 7.5660 (2) Å	µ = 1.45 mm^−1
c = 9.4760 (3) Å	T = 150 K
β = 101.2370 (18)°	Plate, colourless
V = 453.43 (2) Å^3	0.65 × 0.5 × 0.4 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1297 independent reflections
Radiation source: fine-focus sealed tube	1265 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
Detector resolution: 9.091 pixels mm^-1	θmax = 30.1°, θmin = 3.2°
ω scans	h = 0→9
Absorption correction: multi-scan SORTAV (Blessing, 1997)	k = −10→10
Tmin = 0.423, Tmax = 0.571	l = −13→13
6815 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.024	w = 1/[σ^2(Fo^2) + (0.0344P)^2 + 0.2532P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.059	(Δ/σ)max = 0.001
S = 1.18	Δρmax = 0.51 e Å^−3
1297 reflections	Δρmin = −0.50 e Å^−3
77 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.063 (9)
Primary atom site location: structure-invariant direct methods

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K	0.84556 (4)	0.22681 (4)	0.45470 (3)	0.01566 (12)
P	0.61626 (5)	0.70589 (4)	0.33024 (3)	0.00889 (12)
O1	0.64216 (16)	0.86712 (12)	0.43691 (11)	0.0143 (2)
O2	0.40382 (14)	0.61818 (13)	0.35198 (10)	0.0134 (2)
O3	0.59098 (15)	0.77907 (12)	0.18009 (10)	0.0125 (2)
O4	0.79879 (14)	0.57840 (13)	0.37120 (10)	0.0140 (2)
F	0.96623 (14)	0.47367 (12)	0.18426 (10)	0.0220 (2)
H1	0.636 (4)	0.833 (3)	0.518 (3)	0.037 (6)*
H2	0.397 (4)	0.510 (4)	0.338 (3)	0.044 (7)*
H3	0.899 (5)	0.516 (4)	0.252 (4)	0.061 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.01554 (17)	0.01351 (16)	0.01707 (17)	0.00174 (9)	0.00106 (11)	0.00181 (9)
P	0.01097 (17)	0.00808 (17)	0.00789 (17)	0.00009 (10)	0.00249 (11)	0.00018 (9)
O1	0.0219 (5)	0.0116 (4)	0.0106 (4)	−0.0043 (3)	0.0059 (3)	−0.0023 (3)
O2	0.0134 (4)	0.0099 (4)	0.0178 (5)	−0.0016 (3)	0.0054 (3)	−0.0017 (3)
O3	0.0187 (5)	0.0105 (4)	0.0085 (4)	0.0013 (3)	0.0035 (3)	0.0009 (3)
O4	0.0131 (4)	0.0156 (4)	0.0135 (4)	0.0036 (3)	0.0029 (3)	0.0039 (3)
F	0.0198 (4)	0.0264 (5)	0.0211 (4)	0.0021 (3)	0.0069 (3)	−0.0074 (3)

Geometric parameters (Å, º)

K—F^i	2.6416 (9)	P—O2	1.5714 (10)
K—F^ii	2.7382 (10)	P—O3	1.5057 (10)
K—O4	2.7749 (10)	P—O4	1.5127 (9)
K—O3^iii	2.8827 (10)	O1—K^vii	3.0114 (10)
K—O2^iv	2.9096 (10)	O1—K^v	3.3390 (11)
K—O4^v	2.9459 (10)	O2—K^iv	2.9094 (10)
K—O1^vi	3.0114 (10)	O2—K^viii	3.1442 (10)
K—O2^iii	3.1441 (10)	O3—K^viii	2.8827 (10)
K—O1^v	3.3390 (11)	O4—K^v	2.9458 (10)
K—F	3.3821 (10)	F—K^ix	2.6417 (9)
P—O1	1.5722 (10)	F—K^x	2.7382 (10)
F^i—K—F^ii	84.68 (3)	F^i—K—O1^v	60.63 (3)
F^i—K—O4	141.58 (3)	F^ii—K—O1^v	59.63 (3)
F^ii—K—O4	124.55 (3)	O4—K—O1^v	109.74 (3)
F^i—K—O3^iii	123.31 (3)	O3^iii—K—O1^v	170.95 (3)
F^ii—K—O3^iii	111.64 (3)	O2^iv—K—O1^v	121.81 (3)
O4—K—O3^iii	72.52 (3)	O4^v—K—O1^v	47.06 (2)
F^i—K—O2^iv	79.82 (3)	O1^vi—K—O1^v	102.64 (2)
F^ii—K—O2^iv	159.37 (3)	O2^iii—K—O1^v	121.72 (3)
O4—K—O2^iv	75.55 (3)	F^i—K—F	150.08 (4)
O3^iii—K—O2^iv	67.17 (3)	F^ii—K—F	80.382 (11)
F^i—K—O4^v	75.75 (3)	O4—K—F	44.18 (2)
F^ii—K—O4^v	104.46 (3)	O3^iii—K—F	86.42 (3)
O4—K—O4^v	73.12 (3)	O2^iv—K—F	119.44 (3)
O3^iii—K—O4^v	139.98 (3)	O4^v—K—F	83.06 (3)
O2^iv—K—O4^v	84.90 (3)	O1^vi—K—F	128.22 (3)
F^i—K—O1^vi	65.31 (3)	O2^iii—K—F	66.16 (2)
F^ii—K—O1^vi	64.53 (3)	O1^v—K—F	89.47 (2)
O4—K—O1^vi	145.93 (3)	O1—P—O2	103.27 (5)
O3^iii—K—O1^vi	73.87 (3)	O1—P—O3	107.49 (5)
O2^iv—K—O1^vi	96.40 (3)	O1—P—O4	110.49 (6)
O4^v—K—O1^vi	140.04 (3)	O2—P—O3	110.03 (5)
F^i—K—O2^iii	128.79 (3)	O2—P—O4	110.58 (5)
F^ii—K—O2^iii	64.37 (3)	O3—P—O4	114.36 (5)
O4—K—O2^iii	88.82 (3)	P—O1—H1	110 (2)
O3^iii—K—O2^iii	49.23 (3)	P—O2—H2	115 (2)
O2^iv—K—O2^iii	116.20 (3)	P—O3—H1^xi	128.3 (8)
O4^v—K—O2^iii	148.27 (3)	P—O3—H2^viii	117.3 (9)
O1^vi—K—O2^iii	64.74 (3)	P—O4—H3	116 (1)

Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+2, y−1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+1, −y+1, −z+1; (v) −x+2, −y+1, −z+1; (vi) x, y−1, z; (vii) x, y+1, z; (viii) −x+1, y+1/2, −z+1/2; (ix) x, −y+1/2, z−1/2; (x) −x+2, y+1/2, −z+1/2; (xi) x, −y+3/2, z−1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
F—H3···O4	0.90 (3)	1.48 (3)	2.3827 (13)	176 (3)
O1—H1···O3^xii	0.82 (3)	1.83 (3)	2.6342 (14)	169 (3)
O2—H2···O3^iii	0.83 (3)	1.76 (3)	2.5846 (13)	174 (3)

Symmetry codes: (iii) −x+1, y−1/2, −z+1/2; (xii) x, −y+3/2, z+1/2.