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Acta Crystallogr Sect E Struct Rep Online. 2010 August 1; 66(Pt 8): o2132.
Published online 2010 July 31. doi:  10.1107/S160053681002920X
PMCID: PMC3007552

Ammonium hexa­fluorido­phosphate–18-crown-6 (1/1)

Abstract

In the crystal structure of the title compound, NH4 +·PF6 ·C12H24O6, the cation is situated in the 18-crown-6 ring, forming a supra­molecular rotator-stator-like structure held by N—H(...)O hydrogen bonds. The six O atoms of the crown ether lie approximately in a plane [mean deviation 0.2129 (3) Å]; the N atom is displaced by 0.864 (3)Å from the centroid of the 18-crown-6 ring. The slightly distorted tetra­hedral cations further inter­act with the slightly distorted octa­hedral anions via inter­molecular N—H(...)F hydrogen bonds.

Related literature

For background to 18-crown-6 compounds, see: Bajaj & Poonia (1988 [triangle]); Fender et al. (2002 [triangle]); Kryatova et al. (2004 [triangle]). For related structures. see: Dapporto et al. (1996 [triangle]); Pears et al. (1988 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2132-scheme1.jpg

Experimental

Crystal data

  • NH4 +·PF6 ·C12H24O6
  • M r = 427.32
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2132-efi1.jpg
  • a = 12.559 (3) Å
  • b = 8.7352 (17) Å
  • c = 18.6511 (17) Å
  • β = 94.097 (10)°
  • V = 2040.9 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.21 mm−1
  • T = 298 K
  • 0.40 × 0.36 × 0.30 mm

Data collection

  • Rigaku Mercury2 diffractometer
  • Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 [triangle]) T min = 0.920, T max = 0.940
  • 18388 measured reflections
  • 4014 independent reflections
  • 2740 reflections with I > 2σ(I)
  • R int = 0.044

Refinement

  • R[F 2 > 2σ(F 2)] = 0.060
  • wR(F 2) = 0.160
  • S = 1.04
  • 4014 reflections
  • 239 parameters
  • H-atom parameters constrained
  • Δρmax = 0.35 e Å−3
  • Δρmin = −0.27 e Å−3

Data collection: CrystalClear (Rigaku, 2005 [triangle]); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053681002920X/jh2185sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053681002920X/jh2185Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

DHW thanks the China Postdoctoral Science Foundation funded project (20090451147), Jiangsu Planned Projects for Postdoctoral Research Funds (0802003B) and the SEU Major Postdoctoral Research Funds (3212000901) for financial support.

supplementary crystallographic information

Comment

Recently much attention has been devoted to crown ethers due to their ability to form non-covalent, H-bonding complexes with ammonium cations both in solid and in solution (Bajaj et al., 1988; Fender et al., 2002; Kryatova et al., 2004). Both the nature of the ammonium cation (NH4+,RNH3+, R2NH2+, etc.) and the size of the crown ether can work on the stability and stoichiometry of these host–guest complexes. The host molecules combine with the guest species by intermolecular interaction, 18-Crown-6 has a high affinity for RNH3+cations and most studies of 18-crown-6 and its derivatives invariably showed a 1:1 stoichiometry with RNH3+ cations. For similar structures, see: Dapporto et al., 1996; Pears et al., 1988. In our laboratory, the title compound has been synthesized and its crystal structure is herein reported.

The title compound crystallizes in the P21/n space group with an asymmetric unit consisting of a cationic [(NH4)(18-crown-6)]+ moiety and an isolated anionic PF6-(Fig 1). The NH4+ nests in the 18-crown-6 ring to form a superamolecular rotator-stator-like structure by intramolecular N—H···O hydrogen-bonded interactions between the NH4+ (H1C, H1D and H1F)and the six oxygen atoms of the crown ether (Fig 2). Intramolecular N—H···O hydrogen distances fall within the normal range: 2.871 (3) and 3.018 (3) Å (Table 1). The six oxygen atoms of the crown ether lie approximately in a plane with the mean deviation of 0.2129 Å, the N atom aparts from the center of the crown ring about 0.864 Å. The slightly distorted tetrahedralcations NH4+ further interact with F1i and F3i (symmetry code, i: 1 - x, 1 - y, -z) of the slightly distorted octahedral anions PF6- (The P—F bond lengths are within the range of 1.51 - 1.60 Å, the F—P—F bond angles are within the range of 87.78 - 92.48°) by intermolecular N—H···F hydrogen bonds (Table 1 and Fig 2).

Experimental

In room temperature 18-crown-6 (4 mmol, 1.05 g) were dissolved in 50 ml me thanol, after addition of excess hexafluorophosphoric acid to afford a white microcrystallic precipitation for H3O+?PF6-(18-crown-6) (about 95% yield). Then dissolve the precipitation again in 50 ml water and addition of excess concentrated ammonia to afford the solution without any participation under stirring at the ambient temperature. Block colorless single crystals suitable for X-ray structure analysis were obtained by the slow evaporation of the above solution after a week in air.

The dielectric constant of the compound as a function of temperature indicates that the permittivity is basically temperature-independent (ε = C/(T–T0)), suggesting that this compound is not ferroelectric or there may be no distinct phase transition occurring within the measured temperature range between 93 K and433 K (below the compound melting point 463 K).

Refinement

H atoms in the crown ring were placed in calculated positions with C—H = 0.97 Å for Csp3 atoms, assigned fixed Uiso values [Uiso(H) = 1.2Ueq(Csp3)] and allowed to ride. The four H atoms of NH4+ were found with N—H bond distances of between 0.7721 and 0.8282 Å in the difference electron density map.

Figures

Fig. 1.
The molecular structure of the title compound, showing the atomic numbering scheme with 30% probability displacement ellipsoids.
Fig. 2.
The packing of the title compound viewed along the b axis. The i suffix for atoms F1 and F3 denotes a transformation of (1 - x, 1 - y, -z). Hydrogen atoms not involved in hydrogen bonds (dashed lines) are omitted for clarity.

Crystal data

NH4+·PF6·C12H24O6F(000) = 896
Mr = 427.32Dx = 1.391 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 14970 reflections
a = 12.559 (3) Åθ = 3.0–27.8°
b = 8.7352 (17) ŵ = 0.21 mm1
c = 18.6511 (17) ÅT = 298 K
β = 94.097 (10)°Block, colorless
V = 2040.9 (7) Å30.40 × 0.36 × 0.30 mm
Z = 4

Data collection

Rigaku Mercury2 diffractometer4014 independent reflections
Radiation source: fine-focus sealed tube2740 reflections with I > 2σ(I)
graphiteRint = 0.044
Detector resolution: 13.6612 pixels mm-1θmax = 26.0°, θmin = 3.0°
CCD_Profile_fitting scansh = −15→15
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)k = −10→10
Tmin = 0.920, Tmax = 0.940l = −23→23
18388 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.060Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.160H-atom parameters constrained
S = 1.04w = 1/[σ2(Fo2) + (0.0668P)2 + 1.0944P] where P = (Fo2 + 2Fc2)/3
4014 reflections(Δ/σ)max < 0.001
239 parametersΔρmax = 0.35 e Å3
0 restraintsΔρmin = −0.27 e Å3

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.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
C10.9000 (3)0.5093 (4)0.18932 (18)0.0655 (9)
H1A0.95380.44650.21500.079*
H1B0.89140.47360.14000.079*
C20.7979 (3)0.4959 (3)0.22323 (17)0.0642 (9)
H2A0.78040.38880.22950.077*
H2B0.80380.54410.27020.077*
C30.6165 (3)0.5644 (4)0.20892 (18)0.0660 (9)
H3A0.62120.61750.25470.079*
H3B0.59590.45920.21710.079*
C40.5360 (3)0.6394 (4)0.1589 (2)0.0739 (10)
H4A0.53710.59350.11160.089*
H4B0.46540.62490.17570.089*
C50.4855 (3)0.8783 (5)0.1069 (2)0.0886 (12)
H5A0.41350.86340.12120.106*
H5B0.48890.83840.05860.106*
C60.5118 (3)1.0437 (5)0.1080 (2)0.0931 (14)
H6A0.45751.09990.07930.112*
H6B0.51381.08190.15690.112*
C70.6458 (4)1.2199 (4)0.0808 (2)0.0938 (15)
H7A0.65401.25630.13000.113*
H7B0.59201.28220.05470.113*
C80.7494 (5)1.2330 (4)0.0468 (2)0.0967 (16)
H8A0.74371.1844−0.00010.116*
H8B0.76701.34000.04030.116*
C90.9326 (4)1.1636 (4)0.0621 (2)0.0895 (14)
H9A0.95401.26890.05490.107*
H9B0.92771.11270.01580.107*
C101.0131 (3)1.0861 (4)0.1110 (2)0.0822 (12)
H10A1.08321.09720.09280.099*
H10B1.01501.13310.15820.099*
C111.0631 (3)0.8462 (5)0.1619 (2)0.0795 (11)
H11A1.06370.88510.21060.095*
H11B1.13410.85870.14530.095*
C121.0335 (3)0.6825 (5)0.1605 (2)0.0787 (11)
H12A1.02870.64520.11140.094*
H12B1.08760.62340.18800.094*
F10.17131 (17)0.4032 (3)0.03130 (14)0.1043 (8)
F20.18504 (19)0.3563 (3)0.14865 (13)0.1016 (8)
F30.26429 (15)0.2017 (2)0.07209 (11)0.0776 (6)
F40.36548 (17)0.3544 (2)0.14682 (12)0.0929 (7)
F50.34845 (19)0.4032 (3)0.02988 (13)0.1027 (8)
F60.27021 (16)0.5594 (2)0.10520 (12)0.0840 (6)
N10.7710 (2)0.8261 (3)0.09254 (14)0.0488 (6)
H1C0.73570.89830.08820.13 (2)*
H1E0.76760.78820.05430.096 (15)*
H1D0.83310.85340.10390.113 (16)*
H1F0.73930.77190.11670.14 (2)*
O10.93305 (15)0.6644 (2)0.19077 (11)0.0558 (5)
O20.71616 (16)0.5684 (2)0.17870 (10)0.0539 (5)
O30.55889 (15)0.7988 (3)0.15465 (11)0.0620 (6)
O40.6137 (2)1.0656 (2)0.07955 (12)0.0709 (7)
O50.8311 (2)1.1606 (2)0.09173 (11)0.0653 (6)
O60.98772 (17)0.9291 (2)0.11637 (11)0.0631 (6)
P10.26791 (6)0.38092 (9)0.09059 (4)0.0537 (3)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.080 (2)0.0483 (18)0.068 (2)0.0199 (16)−0.0022 (18)0.0009 (15)
C20.094 (3)0.0443 (17)0.0532 (18)−0.0058 (17)−0.0063 (17)0.0113 (14)
C30.076 (2)0.0564 (19)0.068 (2)−0.0250 (17)0.0198 (18)−0.0071 (16)
C40.056 (2)0.080 (2)0.087 (2)−0.0299 (18)0.0119 (18)−0.030 (2)
C50.0465 (19)0.129 (4)0.087 (3)0.008 (2)−0.0148 (18)−0.012 (3)
C60.073 (3)0.110 (3)0.092 (3)0.054 (2)−0.021 (2)−0.008 (2)
C70.135 (4)0.049 (2)0.089 (3)0.032 (2)−0.054 (3)−0.0103 (19)
C80.179 (5)0.045 (2)0.060 (2)−0.015 (3)−0.035 (3)0.0138 (17)
C90.156 (4)0.049 (2)0.070 (2)−0.025 (2)0.055 (3)−0.0036 (17)
C100.084 (3)0.070 (2)0.099 (3)−0.039 (2)0.052 (2)−0.025 (2)
C110.0392 (17)0.115 (3)0.086 (3)−0.0054 (19)0.0125 (17)−0.009 (2)
C120.054 (2)0.096 (3)0.088 (3)0.029 (2)0.0155 (18)0.001 (2)
F10.0796 (15)0.1011 (18)0.1247 (19)0.0091 (12)−0.0443 (14)−0.0083 (14)
F20.1082 (17)0.0858 (15)0.1183 (18)−0.0139 (13)0.0598 (15)−0.0182 (13)
F30.0747 (13)0.0560 (12)0.1020 (15)−0.0021 (9)0.0051 (11)−0.0175 (10)
F40.0879 (15)0.0858 (15)0.0988 (16)0.0013 (12)−0.0361 (12)−0.0043 (12)
F50.0939 (16)0.1138 (19)0.1056 (17)−0.0110 (14)0.0442 (14)0.0028 (14)
F60.0805 (14)0.0547 (11)0.1155 (17)−0.0061 (10)−0.0009 (12)−0.0113 (11)
N10.0531 (16)0.0445 (13)0.0488 (15)−0.0016 (13)0.0033 (11)−0.0026 (12)
O10.0524 (12)0.0529 (12)0.0626 (13)0.0132 (9)0.0082 (10)0.0004 (10)
O20.0625 (13)0.0496 (11)0.0503 (11)−0.0075 (10)0.0083 (10)0.0056 (9)
O30.0420 (11)0.0733 (15)0.0690 (14)−0.0032 (10)−0.0083 (10)−0.0175 (11)
O40.0833 (17)0.0540 (13)0.0717 (15)0.0239 (12)−0.0210 (13)−0.0119 (11)
O50.1022 (18)0.0461 (12)0.0478 (12)−0.0099 (12)0.0068 (12)0.0064 (9)
O60.0569 (13)0.0651 (13)0.0689 (14)−0.0166 (11)0.0165 (11)−0.0052 (11)
P10.0441 (4)0.0524 (5)0.0643 (5)−0.0032 (4)0.0011 (3)−0.0086 (4)

Geometric parameters (Å, °)

C1—O11.416 (4)C8—H8A0.9700
C1—C21.475 (5)C8—H8B0.9700
C1—H1A0.9700C9—O51.424 (5)
C1—H1B0.9700C9—C101.477 (6)
C2—O21.422 (4)C9—H9A0.9700
C2—H2A0.9700C9—H9B0.9700
C2—H2B0.9700C10—O61.413 (4)
C3—O21.410 (4)C10—H10A0.9700
C3—C41.478 (5)C10—H10B0.9700
C3—H3A0.9700C11—O61.423 (4)
C3—H3B0.9700C11—C121.478 (5)
C4—O31.425 (4)C11—H11A0.9700
C4—H4A0.9700C11—H11B0.9700
C4—H4B0.9700C12—O11.426 (4)
C5—O31.417 (4)C12—H12A0.9700
C5—C61.482 (6)C12—H12B0.9700
C5—H5A0.9700F1—P11.594 (2)
C5—H5B0.9700F2—P11.569 (2)
C6—O41.432 (5)F3—P11.6029 (19)
C6—H6A0.9700F4—P11.572 (2)
C6—H6B0.9700F5—P11.583 (2)
C7—O41.407 (4)F6—P11.583 (2)
C7—C81.492 (6)N1—H1C0.7721
C7—H7A0.9700N1—H1E0.7840
C7—H7B0.9700N1—H1D0.8282
C8—O51.427 (5)N1—H1F0.7827
O1—C1—C2109.3 (2)C10—C9—H9A109.6
O1—C1—H1A109.8O5—C9—H9B109.6
C2—C1—H1A109.8C10—C9—H9B109.6
O1—C1—H1B109.8H9A—C9—H9B108.1
C2—C1—H1B109.8O6—C10—C9109.9 (3)
H1A—C1—H1B108.3O6—C10—H10A109.7
O2—C2—C1109.1 (2)C9—C10—H10A109.7
O2—C2—H2A109.9O6—C10—H10B109.7
C1—C2—H2A109.9C9—C10—H10B109.7
O2—C2—H2B109.9H10A—C10—H10B108.2
C1—C2—H2B109.9O6—C11—C12109.0 (3)
H2A—C2—H2B108.3O6—C11—H11A109.9
O2—C3—C4108.9 (3)C12—C11—H11A109.9
O2—C3—H3A109.9O6—C11—H11B109.9
C4—C3—H3A109.9C12—C11—H11B109.9
O2—C3—H3B109.9H11A—C11—H11B108.3
C4—C3—H3B109.9O1—C12—C11109.2 (3)
H3A—C3—H3B108.3O1—C12—H12A109.8
O3—C4—C3109.7 (2)C11—C12—H12A109.8
O3—C4—H4A109.7O1—C12—H12B109.8
C3—C4—H4A109.7C11—C12—H12B109.8
O3—C4—H4B109.7H12A—C12—H12B108.3
C3—C4—H4B109.7H1C—N1—H1E104.9
H4A—C4—H4B108.2H1C—N1—H1D108.4
O3—C5—C6109.5 (3)H1E—N1—H1D110.2
O3—C5—H5A109.8H1C—N1—H1F104.0
C6—C5—H5A109.8H1E—N1—H1F105.7
O3—C5—H5B109.8H1D—N1—H1F122.3
C6—C5—H5B109.8C1—O1—C12111.4 (2)
H5A—C5—H5B108.2C3—O2—C2112.3 (2)
O4—C6—C5109.3 (3)C5—O3—C4112.9 (3)
O4—C6—H6A109.8C7—O4—C6112.6 (3)
C5—C6—H6A109.8C9—O5—C8112.9 (3)
O4—C6—H6B109.8C10—O6—C11113.1 (3)
C5—C6—H6B109.8F2—P1—F492.48 (14)
H6A—C6—H6B108.3F2—P1—F691.19 (12)
O4—C7—C8108.9 (3)F4—P1—F691.52 (12)
O4—C7—H7A109.9F2—P1—F5177.92 (14)
C8—C7—H7A109.9F4—P1—F589.31 (14)
O4—C7—H7B109.9F6—P1—F589.83 (13)
C8—C7—H7B109.9F2—P1—F189.19 (15)
H7A—C7—H7B108.3F4—P1—F1177.60 (14)
O5—C8—C7109.2 (3)F6—P1—F190.16 (12)
O5—C8—H8A109.8F5—P1—F188.99 (15)
C7—C8—H8A109.8F2—P1—F390.29 (11)
O5—C8—H8B109.8F4—P1—F390.49 (11)
C7—C8—H8B109.8F6—P1—F3177.45 (13)
H8A—C8—H8B108.3F5—P1—F388.63 (12)
O5—C9—C10110.1 (3)F1—P1—F387.78 (12)
O5—C9—H9A109.6

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1D···O10.832.582.993 (3)113
N1—H1F···O20.782.152.878 (3)155
N1—H1F···O30.782.432.990 (3)129
N1—H1C···O40.772.122.876 (3)169
N1—H1C···O50.772.583.018 (3)117
N1—H1D···O60.832.052.871 (3)172
N1—H1E···F1i0.782.473.179 (4)151
N1—H1E···F3i0.782.373.080 (3)152

Symmetry codes: (i) −x+1, −y+1, −z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: JH2185).

References

  • Bajaj, A. V. & Poonia, N. S. (1988). Coord. Chem. Rev.87, 55–213.
  • Dapporto, P., Paoli, P., Matijasic, I. & Tusek-Bozic, L. (1996). Inorg. Chim. Acta, 252, 383–389.
  • Fender, N. S., Kahwa, I. A. & Fronczek, F. R. (2002). J. Solid State Chem.163, 286–293.
  • Kryatova, O. P., Korendovych, I. V. & Rybak-Akimova, E. V. (2004). Tetrahedron, 60, 4579–4588.
  • Pears, D. A., Stoddart, J. F., Fakley, M. E., Allwood, B. L. & Williams, D. J. (1988). Acta Cryst. C44, 1426–1430.
  • Rigaku (2005). CrystalClear Rigaku Corporation, Tokyo, Japan.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

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