In the title compound, tetraethylammonium hydroxide pentahydrate, C
8H
20N
+·OH
−·5H
2O, layers of approximately hexagonally close-packed NEt
4+ cations and anionic layers of hydroxide and water molecules are stacked alternately along the
b axis. All hydroxide and water H atoms are in ordered positions, giving rise to a network of hydrogen bonds [O
O 2.633 (1)–2.947 (2) Å] with four- and six-membered rings. The hydroxide ion accepts four hydrogen bonds from four water molecules but does not act as a proton donor.
Supporting information
CCDC reference: 150369
To prepare compound (I), an aqueous solution of NEt4OH, with a molar ratio of base to water of 1:7.8, was sealed in a thin-walled glass capillary with a diameter of 0.3 mm and placed in the cold gas stream of the X-ray diffractometer. Crystal growth was performed at 258 K by applying a miniature zone-melting technique using focused heat radiation (Brodalla et al., 1985).
All H atoms were located on a difference Fourier map and refined independently.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Berndt, 1999); software used to prepare material for publication: SHELXL97.
tetraethylammonium hydroxide-water (1/5)
top
Crystal data top
C8H20N+·OH−·5H2O | Z = 2 |
Mr = 237.34 | F(000) = 268 |
Triclinic, P1 | Dx = 1.112 Mg m−3 |
a = 7.306 (2) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.759 (2) Å | Cell parameters from 25 reflections |
c = 13.141 (3) Å | θ = 11.5–18.1° |
α = 89.28 (2)° | µ = 0.09 mm−1 |
β = 79.34 (2)° | T = 213 K |
γ = 75.63 (2)° | Irregular polyhedron, white |
V = 708.7 (3) Å3 | <0.3 × <0.3 × <0.3 mm |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.022 |
Radiation source: fine-focus sealed tube | θmax = 29.9°, θmin = 2.7° |
Graphite monochromator | h = 0→10 |
ω/2θ scans | k = −10→10 |
4409 measured reflections | l = −18→18 |
4105 independent reflections | 3 standard reflections every 100 reflections |
2584 reflections with I > 2σ(I) | intensity decay: none |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.040 | All H-atom parameters refined |
wR(F2) = 0.108 | w = 1/[σ2(Fo2) + (0.0609P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.98 | (Δ/σ)max = 0.003 |
4105 reflections | Δρmax = 0.22 e Å−3 |
260 parameters | Δρmin = −0.16 e Å−3 |
0 restraints | |
Crystal data top
C8H20N+·OH−·5H2O | γ = 75.63 (2)° |
Mr = 237.34 | V = 708.7 (3) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.306 (2) Å | Mo Kα radiation |
b = 7.759 (2) Å | µ = 0.09 mm−1 |
c = 13.141 (3) Å | T = 213 K |
α = 89.28 (2)° | <0.3 × <0.3 × <0.3 mm |
β = 79.34 (2)° | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.022 |
4409 measured reflections | 3 standard reflections every 100 reflections |
4105 independent reflections | intensity decay: none |
2584 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.108 | All H-atom parameters refined |
S = 0.98 | Δρmax = 0.22 e Å−3 |
4105 reflections | Δρmin = −0.16 e Å−3 |
260 parameters | |
Special details top
Experimental. A reliable estimation of the size and shape of the crystal within the capillary was not possible. |
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) top | x | y | z | Uiso*/Ueq | |
O1 | 1.10373 (14) | 0.12068 (14) | 0.11854 (8) | 0.0423 (2) | |
O2 | 1.07533 (14) | −0.00253 (12) | 0.31269 (7) | 0.0407 (2) | |
O3 | 0.33748 (12) | 0.12563 (13) | 0.38893 (7) | 0.0365 (2) | |
O4 | 0.70400 (14) | 0.06597 (15) | 0.43224 (8) | 0.0454 (2) | |
O5 | 0.42417 (14) | 0.21172 (14) | 0.19468 (8) | 0.0453 (2) | |
O6 | 0.75836 (16) | 0.10009 (14) | 0.05547 (8) | 0.0452 (2) | |
N | 0.72178 (12) | 0.60551 (10) | 0.24365 (6) | 0.02487 (19) | |
C1 | 0.54656 (17) | 0.71502 (16) | 0.31628 (10) | 0.0366 (3) | |
C2 | 0.81596 (17) | 0.44041 (14) | 0.29551 (9) | 0.0322 (2) | |
C3 | 0.85786 (17) | 0.72418 (15) | 0.21483 (10) | 0.0337 (2) | |
C4 | 0.66542 (19) | 0.54216 (17) | 0.14790 (9) | 0.0366 (3) | |
C5 | 0.3964 (2) | 0.6171 (2) | 0.35777 (13) | 0.0498 (3) | |
C7 | 1.0388 (2) | 0.6414 (2) | 0.13963 (12) | 0.0489 (3) | |
C6 | 0.8872 (2) | 0.4746 (2) | 0.39165 (11) | 0.0492 (3) | |
C8 | 0.5766 (3) | 0.6883 (3) | 0.08256 (15) | 0.0604 (5) | |
H1A | 0.499 (2) | 0.815 (2) | 0.2765 (11) | 0.045 (4)* | |
H1B | 0.593 (2) | 0.760 (2) | 0.3705 (12) | 0.053 (4)* | |
H2A | 0.915 (2) | 0.3773 (19) | 0.2467 (11) | 0.040 (3)* | |
H2B | 0.7205 (19) | 0.3729 (18) | 0.3103 (10) | 0.039 (3)* | |
H3A | 0.8856 (19) | 0.7576 (18) | 0.2787 (11) | 0.040 (3)* | |
H3B | 0.783 (2) | 0.826 (2) | 0.1874 (11) | 0.043 (4)* | |
H4A | 0.5835 (19) | 0.4669 (18) | 0.1722 (10) | 0.034 (3)* | |
H4B | 0.782 (2) | 0.463 (2) | 0.1096 (12) | 0.050 (4)* | |
H5A | 0.292 (2) | 0.698 (2) | 0.4003 (13) | 0.062 (5)* | |
H5B | 0.444 (3) | 0.521 (3) | 0.3962 (14) | 0.068 (5)* | |
H5C | 0.347 (3) | 0.568 (3) | 0.3055 (15) | 0.075 (6)* | |
H6A | 0.936 (3) | 0.367 (3) | 0.4238 (14) | 0.077 (5)* | |
H6B | 0.990 (3) | 0.530 (3) | 0.3771 (14) | 0.071 (5)* | |
H6C | 0.786 (3) | 0.550 (3) | 0.4426 (15) | 0.073 (5)* | |
H7A | 1.116 (3) | 0.536 (3) | 0.1644 (14) | 0.068 (5)* | |
H7B | 1.115 (3) | 0.719 (2) | 0.1319 (13) | 0.064 (5)* | |
H7C | 1.016 (3) | 0.614 (3) | 0.0730 (15) | 0.079 (6)* | |
H8A | 0.655 (3) | 0.756 (3) | 0.0567 (14) | 0.073 (6)* | |
H8B | 0.467 (3) | 0.759 (3) | 0.1170 (16) | 0.075 (6)* | |
H8C | 0.543 (3) | 0.635 (3) | 0.0299 (16) | 0.081 (6)* | |
H11 | 1.154 (3) | 0.050 (3) | 0.0749 (16) | 0.067 (6)* | |
H12 | 1.103 (2) | 0.062 (2) | 0.1725 (14) | 0.047 (4)* | |
H21 | 1.144 (3) | 0.039 (2) | 0.3423 (13) | 0.055 (5)* | |
H22 | 0.967 (3) | 0.022 (2) | 0.3517 (15) | 0.067 (5)* | |
H3 | 0.288 (2) | 0.216 (2) | 0.4120 (13) | 0.052 (5)* | |
H41 | 0.597 (3) | 0.088 (2) | 0.4156 (12) | 0.052 (4)* | |
H42 | 0.699 (3) | 0.008 (3) | 0.4852 (16) | 0.066 (5)* | |
H51 | 0.403 (3) | 0.179 (3) | 0.2576 (16) | 0.072 (6)* | |
H52 | 0.339 (3) | 0.195 (2) | 0.1677 (13) | 0.054 (5)* | |
H61 | 0.661 (3) | 0.128 (2) | 0.0986 (14) | 0.063 (5)* | |
H62 | 0.839 (3) | 0.122 (2) | 0.0762 (13) | 0.052 (5)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0418 (5) | 0.0514 (5) | 0.0333 (5) | −0.0136 (4) | −0.0031 (4) | −0.0071 (4) |
O2 | 0.0357 (5) | 0.0509 (5) | 0.0377 (5) | −0.0157 (4) | −0.0048 (4) | −0.0060 (4) |
O3 | 0.0326 (4) | 0.0396 (5) | 0.0358 (4) | −0.0053 (4) | −0.0074 (3) | −0.0024 (4) |
O4 | 0.0329 (5) | 0.0719 (7) | 0.0370 (5) | −0.0245 (5) | −0.0059 (4) | 0.0098 (5) |
O5 | 0.0418 (5) | 0.0662 (6) | 0.0353 (5) | −0.0307 (5) | −0.0025 (4) | 0.0024 (4) |
O6 | 0.0332 (5) | 0.0573 (6) | 0.0412 (5) | −0.0059 (4) | −0.0041 (4) | −0.0079 (4) |
N | 0.0272 (4) | 0.0211 (4) | 0.0264 (4) | −0.0080 (3) | −0.0026 (3) | −0.0004 (3) |
C1 | 0.0319 (6) | 0.0279 (5) | 0.0431 (7) | −0.0012 (4) | 0.0022 (5) | −0.0044 (5) |
C2 | 0.0349 (6) | 0.0239 (5) | 0.0327 (5) | −0.0028 (4) | 0.0001 (5) | 0.0047 (4) |
C3 | 0.0358 (6) | 0.0287 (5) | 0.0415 (6) | −0.0167 (5) | −0.0085 (5) | 0.0047 (5) |
C4 | 0.0473 (7) | 0.0399 (6) | 0.0310 (5) | −0.0249 (6) | −0.0094 (5) | 0.0019 (5) |
C5 | 0.0344 (7) | 0.0518 (8) | 0.0554 (8) | −0.0098 (6) | 0.0103 (6) | −0.0016 (7) |
C7 | 0.0403 (7) | 0.0555 (8) | 0.0528 (8) | −0.0252 (7) | 0.0045 (6) | 0.0043 (7) |
C6 | 0.0477 (8) | 0.0600 (9) | 0.0401 (7) | −0.0116 (7) | −0.0125 (6) | 0.0147 (6) |
C8 | 0.0711 (12) | 0.0750 (11) | 0.0561 (9) | −0.0403 (10) | −0.0364 (9) | 0.0257 (9) |
Geometric parameters (Å, º) top
O3—H3 | 0.745 (17) | C4—H4A | 0.948 (14) |
N—C3 | 1.5119 (14) | C4—H4B | 0.974 (16) |
N—C2 | 1.5143 (14) | C5—H5A | 0.951 (17) |
N—C1 | 1.5166 (14) | C5—H5B | 0.927 (19) |
N—C4 | 1.5172 (14) | C5—H5C | 0.958 (19) |
C1—C5 | 1.5033 (19) | C7—H7A | 0.96 (2) |
C1—H1A | 0.961 (15) | C7—H7B | 0.906 (19) |
C1—H1B | 0.950 (16) | C7—H7C | 0.957 (19) |
C2—C6 | 1.5025 (19) | C6—H6A | 0.95 (2) |
C2—H2A | 0.913 (14) | C6—H6B | 0.94 (2) |
C2—H2B | 0.963 (14) | C6—H6C | 0.98 (2) |
C3—C7 | 1.4991 (19) | C8—H8A | 0.89 (2) |
C3—H3A | 0.952 (14) | C8—H8B | 0.89 (2) |
C3—H3B | 0.948 (15) | C8—H8C | 0.91 (2) |
C4—C8 | 1.504 (2) | | |
| | | |
H2A—O1—O2 | 71.2 (3) | H4A—O5—H52 | 128.3 (12) |
H2A—O1—O6i | 163.6 (3) | O3—O5—H52 | 105.3 (12) |
O2—O1—O6i | 122.73 (5) | O6—O5—H52 | 107.1 (12) |
H2A—O1—O6 | 90.2 (3) | O1iii—O5—H52 | 7.6 (12) |
O2—O1—O6 | 105.00 (5) | O2iii—O5—H52 | 56.1 (12) |
O6i—O1—O6 | 78.22 (5) | H51—O5—H52 | 107.6 (17) |
H2A—O1—O5ii | 80.2 (3) | O5—O6—O1i | 138.04 (6) |
O2—O1—O5ii | 76.37 (4) | O5—O6—O1 | 117.53 (5) |
O6i—O1—O5ii | 110.23 (5) | O1i—O6—O1 | 101.78 (5) |
O6—O1—O5ii | 169.30 (5) | O5—O6—H61 | 3.3 (13) |
H2A—O1—H11 | 173.0 (14) | O1i—O6—H61 | 137.6 (12) |
O2—O1—H11 | 115.2 (14) | O1—O6—H61 | 116.5 (12) |
O6i—O1—H11 | 9.4 (14) | O5—O6—H62 | 109.7 (13) |
O6—O1—H11 | 85.3 (14) | O1i—O6—H62 | 111.0 (13) |
O5ii—O1—H11 | 103.8 (14) | O1—O6—H62 | 10.6 (13) |
H2A—O1—H12 | 82.5 (11) | H61—O6—H62 | 109.2 (18) |
O2—O1—H12 | 11.5 (11) | C3—N—C2 | 111.02 (9) |
O6i—O1—H12 | 111.2 (11) | C3—N—C1 | 106.80 (8) |
O6—O1—H12 | 103.1 (11) | C2—N—C1 | 110.78 (9) |
O5ii—O1—H12 | 80.3 (11) | C3—N—C4 | 110.83 (9) |
H11—O1—H12 | 103.8 (17) | C2—N—C4 | 106.70 (8) |
O1—O2—O3ii | 102.52 (5) | C1—N—C4 | 110.77 (9) |
O1—O2—O4 | 116.16 (5) | C5—C1—N | 114.99 (10) |
O3ii—O2—O4 | 116.88 (5) | C5—C1—H1A | 112.9 (9) |
O1—O2—O5ii | 54.96 (4) | N—C1—H1A | 104.0 (8) |
O3ii—O2—O5ii | 48.15 (3) | C5—C1—H1B | 111.6 (10) |
O4—O2—O5ii | 141.90 (5) | N—C1—H1B | 106.2 (9) |
O1—O2—H21 | 107.7 (12) | H1A—C1—H1B | 106.4 (13) |
O3ii—O2—H21 | 7.2 (12) | C6—C2—N | 115.18 (10) |
O4—O2—H21 | 109.7 (12) | C6—C2—H2A | 110.6 (8) |
O5ii—O2—H21 | 54.2 (12) | N—C2—H2A | 106.3 (9) |
O1—O2—H22 | 118.2 (12) | C6—C2—H2B | 111.1 (8) |
O3ii—O2—H22 | 112.7 (12) | N—C2—H2B | 105.3 (8) |
O4—O2—H22 | 4.2 (12) | H2A—C2—H2B | 107.8 (11) |
O5ii—O2—H22 | 139.3 (13) | C7—C3—N | 115.00 (10) |
H21—O2—H22 | 105.6 (17) | C7—C3—H3A | 111.2 (8) |
O5—O3—O2iii | 81.81 (4) | N—C3—H3A | 105.4 (8) |
O5—O3—O4 | 96.88 (5) | C7—C3—H3B | 111.4 (8) |
O2iii—O3—O4 | 148.33 (5) | N—C3—H3B | 104.3 (9) |
O5—O3—O4iv | 162.91 (5) | H3A—C3—H3B | 109.1 (12) |
O2iii—O3—O4iv | 92.30 (4) | C8—C4—N | 114.80 (11) |
O4—O3—O4iv | 79.73 (4) | C8—C4—H4A | 112.9 (8) |
O5—O3—H3 | 98.8 (13) | N—C4—H4A | 105.6 (8) |
O2iii—O3—H3 | 107.4 (12) | C8—C4—H4B | 112.4 (9) |
O4—O3—H3 | 104.0 (12) | N—C4—H4B | 105.6 (9) |
O4iv—O3—H3 | 98.3 (13) | H4A—C4—H4B | 104.7 (12) |
O3—O4—O3iv | 100.27 (4) | C1—C5—H5A | 108.4 (10) |
O3—O4—O2 | 134.88 (5) | C1—C5—H5B | 111.9 (12) |
O3iv—O4—O2 | 115.99 (5) | H5A—C5—H5B | 109.4 (15) |
O3—O4—H41 | 4.4 (11) | C1—C5—H5C | 114.3 (12) |
O3iv—O4—H41 | 104.6 (11) | H5A—C5—H5C | 107.8 (15) |
O2—O4—H41 | 131.5 (11) | H5B—C5—H5C | 105.0 (16) |
O3—O4—H42 | 103.7 (13) | C3—C7—H7A | 113.5 (11) |
O3iv—O4—H42 | 3.5 (12) | C3—C7—H7B | 108.2 (11) |
O2—O4—H42 | 112.6 (13) | H7A—C7—H7B | 104.2 (15) |
H41—O4—H42 | 108.1 (17) | C3—C7—H7C | 113.0 (12) |
H4A—O5—O3 | 113.7 (3) | H7A—C7—H7C | 108.7 (16) |
H4A—O5—O6 | 72.6 (3) | H7B—C7—H7C | 108.8 (16) |
O3—O5—O6 | 129.47 (5) | C2—C6—H6A | 111.7 (11) |
H4A—O5—O1iii | 135.4 (3) | C2—C6—H6B | 112.0 (11) |
O3—O5—O1iii | 98.17 (4) | H6A—C6—H6B | 105.4 (15) |
O6—O5—O1iii | 110.68 (5) | C2—C6—H6C | 111.8 (11) |
H4A—O5—O2iii | 154.0 (3) | H6A—C6—H6C | 107.9 (16) |
O3—O5—O2iii | 50.04 (3) | H6B—C6—H6C | 107.7 (16) |
O6—O5—O2iii | 133.05 (5) | C4—C8—H8A | 113.4 (12) |
O1iii—O5—O2iii | 48.67 (3) | C4—C8—H8B | 112.4 (13) |
H4A—O5—H51 | 113.4 (13) | H8A—C8—H8B | 108.3 (18) |
O3—O5—H51 | 3.8 (13) | C4—C8—H8C | 107.1 (13) |
O6—O5—H51 | 125.7 (12) | H8A—C8—H8C | 109.5 (17) |
O1iii—O5—H51 | 100.4 (12) | H8B—C8—H8C | 105.9 (17) |
O2iii—O5—H51 | 51.9 (12) | | |
Symmetry codes: (i) −x+2, −y, −z; (ii) x+1, y, z; (iii) x−1, y, z; (iv) −x+1, −y, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H11···O6i | 0.77 (2) | 1.99 (2) | 2.751 (2) | 167 (2) |
O1—H12···O2 | 0.83 (2) | 1.89 (2) | 2.703 (2) | 163 (1) |
O2—H21···O3ii | 0.82 (2) | 1.90 (2) | 2.709 (1) | 170 (2) |
O2—H22···O4 | 0.84 (2) | 1.96 (2) | 2.800 (2) | 174 (2) |
O4—H41···O3 | 0.82 (2) | 1.94 (2) | 2.766 (1) | 174 (2) |
O4—H42···O3iv | 0.83 (2) | 1.95 (2) | 2.774 (1) | 175 (2) |
O5—H51···O3 | 0.86 (2) | 1.78 (2) | 2.633 (1) | 174 (2) |
O5—H52···O1iii | 0.80 (2) | 2.15 (2) | 2.947 (2) | 170 (2) |
O6—H61···O5 | 0.81 (2) | 1.92 (2) | 2.719 (2) | 175 (2) |
O6—H62···O1 | 0.75 (2) | 2.10 (2) | 2.838 (2) | 166 (2) |
C1—H1A···O3v | 0.96 (1) | 2.72 (1) | 3.243 (2) | 115 (1) |
C2—H2A···O1 | 0.91 (1) | 2.56 (1) | 3.425 (2) | 158 (1) |
C3—H3A···O2v | 0.95 (1) | 2.67 (1) | 3.342 (2) | 128 (1) |
C3—H3B···O6v | 0.95 (1) | 2.72 (1) | 3.575 (2) | 150 (1) |
C4—H4A···O5 | 0.95 (1) | 2.52 (1) | 3.444 (2) | 164 (1) |
Symmetry codes: (i) −x+2, −y, −z; (ii) x+1, y, z; (iii) x−1, y, z; (iv) −x+1, −y, −z+1; (v) x, y+1, z. |
Experimental details
Crystal data |
Chemical formula | C8H20N+·OH−·5H2O |
Mr | 237.34 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 213 |
a, b, c (Å) | 7.306 (2), 7.759 (2), 13.141 (3) |
α, β, γ (°) | 89.28 (2), 79.34 (2), 75.63 (2) |
V (Å3) | 708.7 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | <0.3 × <0.3 × <0.3 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4409, 4105, 2584 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.702 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.108, 0.98 |
No. of reflections | 4105 |
No. of parameters | 260 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.22, −0.16 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H11···O6i | 0.77 (2) | 1.99 (2) | 2.751 (2) | 167 (2) |
O1—H12···O2 | 0.83 (2) | 1.89 (2) | 2.703 (2) | 163 (1) |
O2—H21···O3ii | 0.82 (2) | 1.90 (2) | 2.709 (1) | 170 (2) |
O2—H22···O4 | 0.84 (2) | 1.96 (2) | 2.800 (2) | 174 (2) |
O4—H41···O3 | 0.82 (2) | 1.94 (2) | 2.766 (1) | 174 (2) |
O4—H42···O3iii | 0.83 (2) | 1.95 (2) | 2.774 (1) | 175 (2) |
O5—H51···O3 | 0.86 (2) | 1.78 (2) | 2.633 (1) | 174 (2) |
O5—H52···O1iv | 0.80 (2) | 2.15 (2) | 2.947 (2) | 170 (2) |
O6—H61···O5 | 0.81 (2) | 1.92 (2) | 2.719 (2) | 175 (2) |
O6—H62···O1 | 0.75 (2) | 2.10 (2) | 2.838 (2) | 166 (2) |
C1—H1A···O3v | 0.96 (1) | 2.72 (1) | 3.243 (2) | 115 (1) |
C2—H2A···O1 | 0.91 (1) | 2.56 (1) | 3.425 (2) | 158 (1) |
C3—H3A···O2v | 0.95 (1) | 2.67 (1) | 3.342 (2) | 128 (1) |
C3—H3B···O6v | 0.95 (1) | 2.72 (1) | 3.575 (2) | 150 (1) |
C4—H4A···O5 | 0.95 (1) | 2.52 (1) | 3.444 (2) | 164 (1) |
Symmetry codes: (i) −x+2, −y, −z; (ii) x+1, y, z; (iii) −x+1, −y, −z+1; (iv) x−1, y, z; (v) x, y+1, z. |
Higher hydrates of tetraalkylammonium hydroxides crystallize as ionic clathrate hydrates (Jeffrey, 1996). This has been demonstrated in particular for the binary system tetramethylammonium hydroxide-water by detailed phase analytical and structural investigations (Mootz & Seidel, 1990; Mootz & Stäben, 1992; Hesse & Jansen, 1991). As many as ten (stable and metastable) solid hydrate phases containing at least four water molecules per base molecule have been found to exist in that system. Reports of various hydrates of tetraethylammonium hydroxide are also available (Harmon et al., 1994), but only the crystal structure of the tetrahydrate has so far been determined (Wiebcke & Felsche, 2000). In the course of our investigations of alkylammonium silicate heteronetwork clathrates we are also performing structural studies on polyhydrates of alkylammonium hydroxides. Here we report the X-ray structure of the title low-melting tetraethylammonium hydroxide pentahydrate, (I). \sch
One NEt4+ cation of approximate 42m (D2 d) molecular symmetry and one six-membered ring of hydrogen-bonded hydroxide and water molecules, which together comprise the asymmetric unit of (I), are shown in Fig. 1. As can be seen in Fig. 2, slightly corrugated cationic layers, A, and anionic hydroxide-water layers, a, are extended parallel to (010) and stacked alternately along [010] in the sequence AaAa. An anionic layer is based on a planar (3,4)-connected net (Wells, 1984) with a ratio of three- to four-connected nodes of 2:1 [the short Schläfli symbol (O'Keeffe & Brese, 1992) is (4.62)2,(42.62)]. This net contains equal numbers of four- and six-rings.
The four-connected nodes are occupied by the hydroxide ion (atom O3) and one water molecule (O1). The OH− ion does not act as a proton donor but its O3 atom accepts four hydrogen bonds from four water molecules in an approximately square-planar configuration. Each water molecule donates two and accepts two (O1) or one (O2, O4, O5, O6) hydrogen bonds. All H atoms are in ordered positions. The hydrogen-bonding geometry is listed in Table 1. Three crystallographically distinct four- and six-membered oxygen rings exist, which differ in the number of hydroxide ions (two, one, none) involved. The rings containing two or none OH− ions are arranged around inversion centres of the space group; some six-membered rings are slightly puckered. The proton positions clearly reflect the well known cooperativity in extended hydrogen-bonding systems, in that those rings which are built exclusively from water molecules are homodromic (Jeffrey & Saenger, 1994). Cooperativity is interrupted by the OH− ions, which act only as proton acceptors.
The NEt4+ cations in (I) interleave the hydroxide-water layers in two-dimensional approximately hexagonal close-packed arrays, with each N atom being located above and below the centres of two symmetry-related (by translation along [010]) six-membered oxygen rings [Fig. 1 and Fig. 2 (right)]. The water O1, O2, O5 and O6 atoms and the hydroxide O3 atom are each involved in one C—H···O interaction that may be considered as a very weak hydrogen bond. The geometrical parameters are given in Table 1. It should be noted that the C—H···O contact at the OH− ion is in a trans position to the hydroxide proton and that this is the longest and most bent C—H···O interaction considered.
The coordination geometry observed for the OH− ion is quite common in crystalline alkylammonium and metal hydroxide hydrates and also exists in the hydroxide-water ribbons of NEt4OH·4H2O (references are given in Wiebcke & Felsche, 2000). Quite a large number of chemically very different inorganic and organic compounds containing neutral, cationic or anionic hydrogen-bonded layers composed mainly of water molecules have meanwhile been structurally characterized. Such layers have been characterized in some recent compilations according to the sizes of the component rings (Jeffrey, 1996; Mootz & Rütter, 1992; Stäben & Mootz, 1993; Mootz & Stäben, 1993). However, it is interesting also to look at the connectivities of the atoms or molecules in the layers. Most of those layers are based on (3,4)-connected nets with ratios of three- to four-connected nodes of 2:1, which are otherwise rare in crystal chemistry (Wells, 1984). Layers with the same topology as those in (I) occur in the form of neutral water layers in the different forms of deuterated and undeuterated trifluoroacetic acid tetrahydrate (Mootz & Schilling, 1992) and, with regard to the Si atoms, in a layered tetramethylammonium silicate hydrate named RUB15 (Oberhagemann et al., 1996).