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In bis(2-carboxypyridinium) hexafluorosilicate, 2C
6H
6NO
2+·SiF
62−, (I), and bis(2-carboxyquinolinium) hexafluorosilicate dihydrate, 2C
10H
8NO
2+·SiF
62−·2H
2O, (II), the Si atoms of the anions reside on crystallographic centres of inversion. Primary inter-ion interactions in (I) occur
via strong N—H
F and O—H
F hydrogen bonds, generating corrugated layers incorporating [SiF
6]
2− anions as four-connected net nodes and organic cations as simple links in between. In (II), a set of strong N—H
F, O—H
O and O—H
F hydrogen bonds, involving water molecules, gives a three-dimensional heterocoordinated rutile-like framework that integrates [SiF
6]
2− anions as six-connected and water molecules as three-connected nodes. The carboxyl groups of the cation are hydrogen bonded to the water molecule [O
O = 2.5533 (13) Å], while the N—H group supports direct bonding to the anion [N
F = 2.7061 (12) Å].
Supporting information
CCDC references: 661811; 661812
Compounds (I) and (II) were obtained as large colourless prisms by
crystallization of pyridine-2- and quinoline-2-carboxylic acids from aqueous
methanolic hexafluorosilicic acid by slow evaporation of the solutions at room
temperature. In a typical synthesis, pyridine-2-carboxylic acid (0.123 g, 1 mmol) was dissolved in methanol (3 ml) at reflux temperature and this solution
was combined with 45% aqueous H2SiF6 (0.9 ml, molar ratio 1:3). The
reaction mixture was allowed to stand at room temperature until colourless
transparent crystals were deposited (m.p. 455 K [For both compounds?],
without decomposition).
All H atoms were located in difference maps and then treated as riding, with
O—H distances constrained to 0.85 Å, N—H distances constrained to 0.88 Å and C—H distances constrained to 0.95 Å, and with Uiso(H) =
1.2Ueq(C) or 1.5Ueq(N,O).
For both compounds, data collection: IPDS Software (Stoe & Cie, 2000); cell refinement: IPDS Software; data reduction: IPDS Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Version 1.700.00; Farrugia, 1999).
(I) bis(2-carboxypyridinium) hexafluorosilicate
top
Crystal data top
2C6H6NO2+·SiF62− | F(000) = 396 |
Mr = 390.33 | Dx = 1.796 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 8000 reflections |
a = 9.3571 (9) Å | θ = 5.2–29.2° |
b = 7.8717 (6) Å | µ = 0.26 mm−1 |
c = 9.8053 (8) Å | T = 173 K |
β = 91.943 (7)° | Prism, colourless |
V = 721.81 (11) Å3 | 0.17 × 0.16 × 0.14 mm |
Z = 2 | |
Data collection top
Stoe IPDS diffractometer | 1646 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.059 |
Graphite monochromator | θmax = 29.2°, θmin = 5.2° |
ϕ oscillation scans | h = −12→12 |
9005 measured reflections | k = −10→10 |
1935 independent reflections | l = −11→13 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.033 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.092 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.052P)2 + 0.1245P] where P = (Fo2 + 2Fc2)/3 |
1935 reflections | (Δ/σ)max < 0.001 |
115 parameters | Δρmax = 0.39 e Å−3 |
0 restraints | Δρmin = −0.34 e Å−3 |
Crystal data top
2C6H6NO2+·SiF62− | V = 721.81 (11) Å3 |
Mr = 390.33 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 9.3571 (9) Å | µ = 0.26 mm−1 |
b = 7.8717 (6) Å | T = 173 K |
c = 9.8053 (8) Å | 0.17 × 0.16 × 0.14 mm |
β = 91.943 (7)° | |
Data collection top
Stoe IPDS diffractometer | 1646 reflections with I > 2σ(I) |
9005 measured reflections | Rint = 0.059 |
1935 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.033 | 0 restraints |
wR(F2) = 0.092 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.39 e Å−3 |
1935 reflections | Δρmin = −0.34 e Å−3 |
115 parameters | |
Special details top
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 | |
Si1 | 0.5000 | 1.0000 | 0.5000 | 0.02122 (13) | |
F1 | 0.36248 (9) | 0.93406 (12) | 0.39766 (8) | 0.0348 (2) | |
F2 | 0.61426 (9) | 0.96395 (14) | 0.37712 (9) | 0.0426 (2) | |
F3 | 0.52401 (11) | 0.79818 (11) | 0.55815 (12) | 0.0475 (3) | |
O1 | 0.16903 (12) | 1.03075 (14) | 0.15344 (11) | 0.0374 (2) | |
O2 | 0.15962 (11) | 1.05496 (14) | −0.07533 (11) | 0.0355 (2) | |
H1 | 0.0895 | 1.1209 | −0.0616 | 0.053* | |
N1 | 0.39766 (11) | 0.82488 (14) | 0.14285 (11) | 0.0252 (2) | |
H2 | 0.3601 | 0.8556 | 0.2201 | 0.038* | |
C1 | 0.21005 (13) | 0.99580 (16) | 0.04209 (14) | 0.0266 (3) | |
C2 | 0.33467 (12) | 0.87779 (15) | 0.02501 (13) | 0.0236 (2) | |
C3 | 0.39068 (15) | 0.83139 (18) | −0.09757 (14) | 0.0301 (3) | |
H3 | 0.3468 | 0.8670 | −0.1815 | 0.036* | |
C4 | 0.51343 (16) | 0.73080 (18) | −0.09546 (16) | 0.0335 (3) | |
H4 | 0.5544 | 0.6979 | −0.1788 | 0.040* | |
C5 | 0.57568 (14) | 0.67883 (17) | 0.02724 (16) | 0.0313 (3) | |
H5 | 0.6593 | 0.6104 | 0.0290 | 0.038* | |
C6 | 0.51464 (14) | 0.72772 (17) | 0.14755 (15) | 0.0293 (3) | |
H6 | 0.5556 | 0.6924 | 0.2329 | 0.035* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Si1 | 0.0238 (2) | 0.0223 (2) | 0.0177 (2) | −0.00467 (16) | 0.00247 (16) | −0.00045 (16) |
F1 | 0.0295 (4) | 0.0498 (5) | 0.0249 (4) | −0.0097 (3) | −0.0005 (3) | −0.0070 (3) |
F2 | 0.0337 (4) | 0.0669 (6) | 0.0280 (4) | −0.0083 (4) | 0.0107 (3) | −0.0132 (4) |
F3 | 0.0461 (5) | 0.0284 (4) | 0.0674 (7) | −0.0056 (4) | −0.0082 (5) | 0.0138 (4) |
O1 | 0.0379 (5) | 0.0415 (6) | 0.0331 (6) | 0.0109 (4) | 0.0059 (4) | −0.0036 (4) |
O2 | 0.0335 (5) | 0.0395 (5) | 0.0332 (5) | 0.0095 (4) | −0.0012 (4) | 0.0030 (4) |
N1 | 0.0269 (5) | 0.0274 (5) | 0.0216 (5) | 0.0007 (4) | 0.0047 (4) | −0.0007 (4) |
C1 | 0.0245 (5) | 0.0260 (5) | 0.0293 (6) | −0.0004 (4) | 0.0010 (5) | −0.0016 (5) |
C2 | 0.0239 (5) | 0.0238 (5) | 0.0234 (6) | −0.0027 (4) | 0.0026 (4) | −0.0011 (4) |
C3 | 0.0349 (6) | 0.0323 (6) | 0.0232 (6) | −0.0009 (5) | 0.0026 (5) | −0.0016 (5) |
C4 | 0.0361 (7) | 0.0332 (7) | 0.0320 (7) | −0.0011 (5) | 0.0130 (5) | −0.0070 (5) |
C5 | 0.0267 (6) | 0.0257 (6) | 0.0419 (8) | 0.0013 (4) | 0.0073 (5) | −0.0026 (5) |
C6 | 0.0280 (6) | 0.0281 (6) | 0.0316 (7) | 0.0007 (5) | 0.0000 (5) | 0.0025 (5) |
Geometric parameters (Å, º) top
Si1—F1 | 1.6866 (8) | N1—H2 | 0.8800 |
Si1—F2 | 1.6621 (8) | C1—C2 | 1.5047 (17) |
Si1—F3 | 1.7003 (9) | C2—C3 | 1.3767 (18) |
Si1—F2i | 1.6621 (8) | C3—C4 | 1.395 (2) |
Si1—F1i | 1.6866 (8) | C3—H3 | 0.9500 |
Si1—F3i | 1.7003 (9) | C4—C5 | 1.381 (2) |
O1—C1 | 1.2015 (17) | C4—H4 | 0.9500 |
O2—C1 | 1.3147 (17) | C5—C6 | 1.383 (2) |
O2—H1 | 0.8500 | C5—H5 | 0.9500 |
N1—C2 | 1.3453 (16) | C6—H6 | 0.9500 |
N1—C6 | 1.3349 (17) | | |
| | | |
F1—Si1—F2 | 90.73 (4) | O1—C1—O2 | 126.77 (13) |
F1—Si1—F3 | 90.08 (5) | O1—C1—C2 | 121.01 (12) |
F2—Si1—F3 | 90.15 (6) | O2—C1—C2 | 112.19 (11) |
F2—Si1—F2i | 180.0 | N1—C2—C3 | 119.94 (12) |
F2i—Si1—F1 | 89.27 (4) | N1—C2—C1 | 114.46 (11) |
F2—Si1—F1i | 89.27 (4) | C3—C2—C1 | 125.48 (12) |
F2i—Si1—F1i | 90.73 (4) | C2—C3—C4 | 118.39 (13) |
F1—Si1—F1i | 180.0 | C2—C3—H3 | 120.8 |
F2—Si1—F3i | 89.85 (6) | C4—C3—H3 | 120.8 |
F2i—Si1—F3i | 90.15 (6) | C5—C4—C3 | 120.26 (12) |
F1—Si1—F3i | 89.92 (5) | C5—C4—H4 | 119.9 |
F1i—Si1—F3i | 90.08 (5) | C3—C4—H4 | 119.9 |
F2i—Si1—F3 | 89.85 (6) | C4—C5—C6 | 119.12 (12) |
F1i—Si1—F3 | 89.92 (5) | C4—C5—H5 | 120.4 |
F3i—Si1—F3 | 180.0 | C6—C5—H5 | 120.4 |
C1—O2—H1 | 109.4 | N1—C6—C5 | 119.47 (13) |
C6—N1—C2 | 122.81 (12) | N1—C6—H6 | 120.3 |
C6—N1—H2 | 118.6 | C5—C6—H6 | 120.3 |
C2—N1—H2 | 118.6 | | |
| | | |
C6—N1—C2—C3 | 0.16 (19) | N1—C2—C3—C4 | −0.57 (19) |
C6—N1—C2—C1 | −176.06 (11) | C1—C2—C3—C4 | 175.21 (12) |
O1—C1—C2—N1 | −3.27 (18) | C2—C3—C4—C5 | 0.5 (2) |
O2—C1—C2—N1 | 174.75 (11) | C3—C4—C5—C6 | 0.0 (2) |
O1—C1—C2—C3 | −179.25 (13) | C2—N1—C6—C5 | 0.36 (19) |
O2—C1—C2—C3 | −1.22 (18) | C4—C5—C6—N1 | −0.46 (19) |
Symmetry code: (i) −x+1, −y+2, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H1···F3ii | 0.85 | 1.76 | 2.5819 (14) | 163 |
N1—H2···F1 | 0.88 | 1.85 | 2.6730 (14) | 156 |
C3—H3···F2iii | 0.95 | 2.37 | 3.1785 (18) | 142 |
C5—H5···F1iv | 0.95 | 2.36 | 3.1364 (15) | 139 |
C5—H5···F2v | 0.95 | 2.56 | 3.4602 (16) | 159 |
C6—H6···F2 | 0.95 | 2.61 | 3.0416 (17) | 108 |
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1, −y+2, −z; (iv) x+1/2, −y+3/2, z−1/2; (v) −x+3/2, y−1/2, −z+1/2. |
(II) bis(2-carboxyquinolinium) hexafluorosilicate dihydrate
top
Crystal data top
2C10H8NO2+·SiF62−·2H2O | F(000) = 540 |
Mr = 526.47 | Dx = 1.638 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 8000 reflections |
a = 6.6382 (6) Å | θ = 4.2–28.7° |
b = 9.4274 (9) Å | µ = 0.21 mm−1 |
c = 17.0668 (14) Å | T = 173 K |
β = 91.731 (8)° | Prism, colourless |
V = 1067.57 (17) Å3 | 0.16 × 0.12 × 0.12 mm |
Z = 2 | |
Data collection top
Stoe IPDS diffractometer | 2368 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.039 |
Graphite monochromator | θmax = 28.7°, θmin = 4.2° |
ϕ oscillation scans | h = −8→8 |
9457 measured reflections | k = −11→12 |
2697 independent reflections | l = −23→23 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.037 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.102 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0645P)2 + 0.1838P] where P = (Fo2 + 2Fc2)/3 |
2697 reflections | (Δ/σ)max = 0.001 |
160 parameters | Δρmax = 0.36 e Å−3 |
0 restraints | Δρmin = −0.42 e Å−3 |
Crystal data top
2C10H8NO2+·SiF62−·2H2O | V = 1067.57 (17) Å3 |
Mr = 526.47 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.6382 (6) Å | µ = 0.21 mm−1 |
b = 9.4274 (9) Å | T = 173 K |
c = 17.0668 (14) Å | 0.16 × 0.12 × 0.12 mm |
β = 91.731 (8)° | |
Data collection top
Stoe IPDS diffractometer | 2368 reflections with I > 2σ(I) |
9457 measured reflections | Rint = 0.039 |
2697 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.102 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.36 e Å−3 |
2697 reflections | Δρmin = −0.42 e Å−3 |
160 parameters | |
Special details top
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 | |
Si1 | 0.0000 | 1.0000 | 0.0000 | 0.01827 (13) | |
F1 | −0.13372 (15) | 0.85074 (9) | −0.01654 (5) | 0.0344 (2) | |
F2 | 0.21475 (14) | 0.90448 (10) | 0.00028 (5) | 0.0372 (2) | |
F3 | −0.01742 (15) | 0.97419 (9) | 0.09716 (4) | 0.0320 (2) | |
N1 | 0.00238 (16) | 0.80562 (10) | 0.22550 (5) | 0.0181 (2) | |
H2 | 0.0148 | 0.8731 | 0.1904 | 0.027* | |
O1 | 0.00108 (17) | 1.08423 (9) | 0.26607 (5) | 0.0291 (2) | |
O2 | −0.06845 (16) | 1.02390 (10) | 0.39032 (5) | 0.0268 (2) | |
H1 | −0.0581 | 1.1124 | 0.3992 | 0.040* | |
O3 | −0.04700 (15) | 1.28339 (10) | 0.43257 (6) | 0.0280 (2) | |
H1W | 0.0576 | 1.3249 | 0.4513 | 0.042* | |
H2W | −0.1471 | 1.3088 | 0.4591 | 0.042* | |
C1 | −0.03228 (19) | 0.99880 (12) | 0.31666 (7) | 0.0207 (2) | |
C2 | −0.03183 (19) | 0.84206 (12) | 0.29950 (6) | 0.0185 (2) | |
C3 | −0.0591 (2) | 0.73930 (13) | 0.35668 (7) | 0.0238 (3) | |
H3 | −0.0857 | 0.7661 | 0.4090 | 0.029* | |
C4 | −0.0470 (2) | 0.59864 (13) | 0.33654 (7) | 0.0247 (3) | |
H4 | −0.0675 | 0.5276 | 0.3749 | 0.030* | |
C5 | −0.00428 (18) | 0.55933 (12) | 0.25927 (7) | 0.0204 (2) | |
C6 | 0.0123 (2) | 0.41542 (13) | 0.23594 (8) | 0.0252 (3) | |
H6 | −0.0042 | 0.3418 | 0.2732 | 0.030* | |
C7 | 0.0519 (2) | 0.38259 (14) | 0.15987 (8) | 0.0273 (3) | |
H7 | 0.0616 | 0.2861 | 0.1443 | 0.033* | |
C8 | 0.0786 (2) | 0.49187 (14) | 0.10420 (8) | 0.0274 (3) | |
H8 | 0.1095 | 0.4672 | 0.0520 | 0.033* | |
C9 | 0.0608 (2) | 0.63265 (13) | 0.12373 (7) | 0.0231 (3) | |
H9 | 0.0763 | 0.7048 | 0.0856 | 0.028* | |
C10 | 0.01901 (18) | 0.66700 (12) | 0.20210 (6) | 0.0181 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Si1 | 0.0237 (3) | 0.0179 (2) | 0.0135 (2) | 0.00397 (16) | 0.00425 (16) | 0.00405 (14) |
F1 | 0.0435 (5) | 0.0291 (4) | 0.0310 (4) | −0.0100 (3) | 0.0093 (3) | −0.0023 (3) |
F2 | 0.0339 (5) | 0.0419 (5) | 0.0361 (5) | 0.0188 (4) | 0.0068 (3) | 0.0062 (3) |
F3 | 0.0516 (6) | 0.0294 (4) | 0.0154 (3) | 0.0058 (3) | 0.0070 (3) | 0.0063 (3) |
N1 | 0.0215 (5) | 0.0146 (4) | 0.0181 (4) | −0.0001 (3) | 0.0003 (3) | 0.0034 (3) |
O1 | 0.0459 (6) | 0.0161 (4) | 0.0253 (5) | −0.0011 (4) | −0.0018 (4) | 0.0025 (3) |
O2 | 0.0346 (6) | 0.0201 (4) | 0.0261 (5) | −0.0014 (3) | 0.0062 (4) | −0.0039 (3) |
O3 | 0.0307 (5) | 0.0238 (4) | 0.0298 (5) | 0.0002 (4) | 0.0026 (4) | −0.0072 (3) |
C1 | 0.0215 (6) | 0.0167 (5) | 0.0237 (5) | 0.0010 (4) | −0.0020 (4) | −0.0006 (4) |
C2 | 0.0196 (6) | 0.0165 (5) | 0.0193 (5) | −0.0001 (4) | 0.0001 (4) | 0.0016 (4) |
C3 | 0.0305 (7) | 0.0212 (6) | 0.0198 (5) | 0.0016 (5) | 0.0039 (4) | 0.0036 (4) |
C4 | 0.0307 (7) | 0.0197 (5) | 0.0242 (6) | 0.0000 (4) | 0.0050 (5) | 0.0073 (4) |
C5 | 0.0208 (6) | 0.0157 (5) | 0.0246 (5) | 0.0000 (4) | 0.0009 (4) | 0.0033 (4) |
C6 | 0.0243 (7) | 0.0165 (5) | 0.0346 (7) | 0.0003 (4) | −0.0004 (5) | 0.0024 (4) |
C7 | 0.0250 (7) | 0.0196 (6) | 0.0369 (7) | 0.0034 (5) | −0.0052 (5) | −0.0059 (5) |
C8 | 0.0276 (7) | 0.0291 (7) | 0.0251 (6) | 0.0061 (5) | −0.0045 (5) | −0.0062 (5) |
C9 | 0.0253 (7) | 0.0237 (6) | 0.0201 (5) | 0.0038 (5) | −0.0013 (4) | 0.0009 (4) |
C10 | 0.0182 (6) | 0.0158 (5) | 0.0203 (5) | 0.0007 (4) | −0.0006 (4) | 0.0016 (4) |
Geometric parameters (Å, º) top
Si1—F1 | 1.6830 (8) | C2—C3 | 1.3907 (16) |
Si1—F2 | 1.6861 (8) | C3—C4 | 1.3728 (18) |
Si1—F3 | 1.6834 (7) | C3—H3 | 0.9500 |
Si1—F1i | 1.6830 (8) | C4—C5 | 1.4069 (17) |
Si1—F3i | 1.6834 (7) | C4—H4 | 0.9500 |
Si1—F2i | 1.6861 (8) | C5—C6 | 1.4191 (16) |
N1—C2 | 1.3349 (14) | C5—C10 | 1.4196 (15) |
N1—C10 | 1.3718 (14) | C6—C7 | 1.3679 (19) |
N1—H2 | 0.8800 | C6—H6 | 0.9500 |
O1—C1 | 1.2061 (15) | C7—C8 | 1.416 (2) |
O2—C1 | 1.3086 (15) | C7—H7 | 0.9500 |
O2—H1 | 0.8500 | C8—C9 | 1.3742 (17) |
O3—H1W | 0.8500 | C8—H8 | 0.9500 |
O3—H2W | 0.8500 | C9—C10 | 1.4119 (16) |
C1—C2 | 1.5065 (15) | C9—H9 | 0.9500 |
| | | |
F1—Si1—F2 | 89.74 (5) | C3—C2—C1 | 123.08 (11) |
F1—Si1—F3 | 89.59 (4) | C4—C3—C2 | 119.16 (11) |
F2—Si1—F3 | 90.19 (4) | C4—C3—H3 | 120.4 |
F1i—Si1—F1 | 180.00 (6) | C2—C3—H3 | 120.4 |
F1i—Si1—F3i | 89.59 (4) | C3—C4—C5 | 120.27 (11) |
F1—Si1—F3i | 90.41 (4) | C3—C4—H4 | 119.9 |
F1i—Si1—F3 | 90.41 (4) | C5—C4—H4 | 119.9 |
F3i—Si1—F3 | 180.00 (6) | C4—C5—C6 | 122.30 (11) |
F1i—Si1—F2 | 90.26 (5) | C4—C5—C10 | 119.02 (11) |
F3i—Si1—F2 | 89.81 (4) | C6—C5—C10 | 118.67 (11) |
F1i—Si1—F2i | 89.74 (5) | C7—C6—C5 | 120.09 (12) |
F1—Si1—F2i | 90.26 (5) | C7—C6—H6 | 120.0 |
F3i—Si1—F2i | 90.19 (4) | C5—C6—H6 | 120.0 |
F3—Si1—F2i | 89.81 (4) | C6—C7—C8 | 120.24 (12) |
F2—Si1—F2i | 180.0 | C6—C7—H7 | 119.9 |
C2—N1—C10 | 122.55 (9) | C8—C7—H7 | 119.9 |
C2—N1—H2 | 118.7 | C9—C8—C7 | 121.77 (12) |
C10—N1—H2 | 118.7 | C9—C8—H8 | 119.1 |
C1—O2—H1 | 109.5 | C7—C8—H8 | 119.1 |
H1W—O3—H2W | 108.3 | C8—C9—C10 | 118.16 (11) |
O1—C1—O2 | 127.59 (11) | C8—C9—H9 | 120.9 |
O1—C1—C2 | 120.95 (11) | C10—C9—H9 | 120.9 |
O2—C1—C2 | 111.45 (10) | N1—C10—C9 | 120.94 (10) |
N1—C2—C3 | 120.93 (10) | N1—C10—C5 | 118.01 (10) |
N1—C2—C1 | 115.96 (10) | C9—C10—C5 | 121.04 (11) |
| | | |
C10—N1—C2—C3 | −2.12 (18) | C10—C5—C6—C7 | 0.65 (19) |
C10—N1—C2—C1 | 176.07 (11) | C5—C6—C7—C8 | 0.6 (2) |
O1—C1—C2—N1 | −1.58 (19) | C6—C7—C8—C9 | −1.6 (2) |
O2—C1—C2—N1 | 179.53 (11) | C7—C8—C9—C10 | 1.3 (2) |
O1—C1—C2—C3 | 176.57 (13) | C2—N1—C10—C9 | −178.22 (12) |
O2—C1—C2—C3 | −2.32 (18) | C2—N1—C10—C5 | 0.91 (17) |
N1—C2—C3—C4 | 1.1 (2) | C8—C9—C10—N1 | 179.08 (12) |
C1—C2—C3—C4 | −176.94 (12) | C8—C9—C10—C5 | −0.03 (19) |
C2—C3—C4—C5 | 1.0 (2) | C4—C5—C10—N1 | 1.21 (18) |
C3—C4—C5—C6 | 179.18 (13) | C6—C5—C10—N1 | 179.92 (11) |
C3—C4—C5—C10 | −2.2 (2) | C4—C5—C10—C9 | −179.66 (12) |
C4—C5—C6—C7 | 179.32 (13) | C6—C5—C10—C9 | −0.95 (18) |
Symmetry code: (i) −x, −y+2, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H2···F3 | 0.88 | 1.86 | 2.7061 (12) | 160 |
O2—H1···O3 | 0.85 | 1.71 | 2.5531 (13) | 171 |
O3—H1W···F2ii | 0.85 | 1.86 | 2.7070 (13) | 175 |
O3—H2W···F1iii | 0.85 | 1.82 | 2.6707 (13) | 176 |
C3—H3···F2iv | 0.95 | 2.63 | 3.2125 (15) | 120 |
C4—H4···O3v | 0.95 | 2.51 | 3.3940 (15) | 156 |
C4—H4···F2iv | 0.95 | 2.69 | 3.2526 (15) | 118 |
C6—H6···O1v | 0.95 | 2.43 | 3.1655 (16) | 134 |
C7—H7···F1vi | 0.95 | 2.59 | 3.3463 (16) | 137 |
C9—H9···F1 | 0.95 | 2.59 | 3.3823 (15) | 141 |
C9—H9···F2 | 0.95 | 2.57 | 3.4900 (16) | 164 |
C9—H9···F3 | 0.95 | 2.62 | 3.2907 (15) | 128 |
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x−1/2, y+1/2, −z+1/2; (iv) x−1/2, −y+3/2, z+1/2; (v) x, y−1, z; (vi) −x, −y+1, −z. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | 2C6H6NO2+·SiF62− | 2C10H8NO2+·SiF62−·2H2O |
Mr | 390.33 | 526.47 |
Crystal system, space group | Monoclinic, P21/n | Monoclinic, P21/n |
Temperature (K) | 173 | 173 |
a, b, c (Å) | 9.3571 (9), 7.8717 (6), 9.8053 (8) | 6.6382 (6), 9.4274 (9), 17.0668 (14) |
β (°) | 91.943 (7) | 91.731 (8) |
V (Å3) | 721.81 (11) | 1067.57 (17) |
Z | 2 | 2 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.26 | 0.21 |
Crystal size (mm) | 0.17 × 0.16 × 0.14 | 0.16 × 0.12 × 0.12 |
|
Data collection |
Diffractometer | Stoe IPDS diffractometer | Stoe IPDS diffractometer |
Absorption correction | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9005, 1935, 1646 | 9457, 2697, 2368 |
Rint | 0.059 | 0.039 |
(sin θ/λ)max (Å−1) | 0.686 | 0.676 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.033, 0.092, 1.04 | 0.037, 0.102, 1.05 |
No. of reflections | 1935 | 2697 |
No. of parameters | 115 | 160 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.39, −0.34 | 0.36, −0.42 |
Selected geometric parameters (Å, º) for (I) topSi1—F1 | 1.6866 (8) | O2—C1 | 1.3147 (17) |
Si1—F2 | 1.6621 (8) | N1—C2 | 1.3453 (16) |
Si1—F3 | 1.7003 (9) | N1—C6 | 1.3349 (17) |
O1—C1 | 1.2015 (17) | C1—C2 | 1.5047 (17) |
| | | |
F1—Si1—F2 | 90.73 (4) | O1—C1—O2 | 126.77 (13) |
F1—Si1—F3 | 90.08 (5) | O1—C1—C2 | 121.01 (12) |
F2—Si1—F3 | 90.15 (6) | O2—C1—C2 | 112.19 (11) |
| | | |
O2—C1—C2—C3 | −1.22 (18) | | |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H1···F3i | 0.85 | 1.76 | 2.5819 (14) | 163 |
N1—H2···F1 | 0.88 | 1.85 | 2.6730 (14) | 156 |
C3—H3···F2ii | 0.95 | 2.37 | 3.1785 (18) | 142 |
C5—H5···F1iii | 0.95 | 2.36 | 3.1364 (15) | 139 |
C5—H5···F2iv | 0.95 | 2.56 | 3.4602 (16) | 159 |
C6—H6···F2 | 0.95 | 2.61 | 3.0416 (17) | 108 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x+1, −y+2, −z; (iii) x+1/2, −y+3/2, z−1/2; (iv) −x+3/2, y−1/2, −z+1/2. |
Selected geometric parameters (Å, º) for (II) topSi1—F1 | 1.6830 (8) | N1—C10 | 1.3718 (14) |
Si1—F2 | 1.6861 (8) | O1—C1 | 1.2061 (15) |
Si1—F3 | 1.6834 (7) | O2—C1 | 1.3086 (15) |
N1—C2 | 1.3349 (14) | C1—C2 | 1.5065 (15) |
| | | |
F1—Si1—F2 | 89.74 (5) | O1—C1—O2 | 127.59 (11) |
F1—Si1—F3 | 89.59 (4) | O1—C1—C2 | 120.95 (11) |
F2—Si1—F3 | 90.19 (4) | O2—C1—C2 | 111.45 (10) |
| | | |
O1—C1—C2—N1 | −1.58 (19) | | |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H2···F3 | 0.88 | 1.86 | 2.7061 (12) | 160 |
O2—H1···O3 | 0.85 | 1.71 | 2.5531 (13) | 171 |
O3—H1W···F2i | 0.85 | 1.86 | 2.7070 (13) | 175 |
O3—H2W···F1ii | 0.85 | 1.82 | 2.6707 (13) | 176 |
C3—H3···F2iii | 0.95 | 2.63 | 3.2125 (15) | 120 |
C4—H4···O3iv | 0.95 | 2.51 | 3.3940 (15) | 156 |
C4—H4···F2iii | 0.95 | 2.69 | 3.2526 (15) | 118 |
C6—H6···O1iv | 0.95 | 2.43 | 3.1655 (16) | 134 |
C7—H7···F1v | 0.95 | 2.59 | 3.3463 (16) | 137 |
C9—H9···F1 | 0.95 | 2.59 | 3.3823 (15) | 141 |
C9—H9···F2 | 0.95 | 2.57 | 3.4900 (16) | 164 |
C9—H9···F3 | 0.95 | 2.62 | 3.2907 (15) | 128 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x−1/2, y+1/2, −z+1/2; (iii) x−1/2, −y+3/2, z+1/2; (iv) x, y−1, z; (v) −x, −y+1, −z. |
Carbonyl···π contacts (Å, °) for (II) topO atom | C···O range (Å) | O···π (Å) | O···plane (Å) | ϕ (°) |
O1v | 3.31–3.71 | 3.2240 (11) | 3.1830 (13) | 80.9 (2) |
O2vi | 3.40–3.77 | 3.3008 (11) | 3.2626 (13) | 81.3 (2) |
Notes:
For details, see Fig. 7. ϕ is the angle of the O···π axis to the plane of
the aromatic ring.
[Symmetry codes: (v) 1/2-x, y-1/2, 1/2-z; (vi) -1/2-x, y-1/2, 1/2-z.] |
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Fluorosilicate salts involving onium cations of N– and O-containing organic bases have practical applications as ionic liquids (Katayama et al., 2001), dielectrics with cryptocrystalline structure (Kalem, 2004), layered organic–inorganic hybrid materials (Airoldi & De Farias, 2000) and chemical reagents (Han et al., 2000; Gelmboldt, 1989). Their structure is commonly dominated by strong directional interactions involving F atoms and convenient hydrogen-bond donors, although the relationships in such systems could be more complicated due to the presence of competitive OH and NH binding sites, inclusion of solvent molecules and extensive weak C—H···F hydrogen bonding, as occurs for 4-carboxyanilinium hexafluorosilicate hydrate (Gelmboldt et al., 2004). Therefore, heteroaromatic onium cations combining sets of typical hydrogen-bond donating functions (such as NH+, COOH, CONH2 etc.) are especially well suited for the examination of the hydrogen-bonding preferences of [SiF6]2- and its utility as a rigid building block for the design of framework structures. In this context, we have prepared two new [SiF6]2- salts involving the cations 2-carboxypyridinium and 2-carboxyquinolinium as ambidentate N—H/O—H hydrogen-bond donors, to give the title compounds, (I) and (II), respectively, and report their structures here.
Compounds (I) and (II) adopt complicated framework structures originating in strong hydrogen bonding between the cationic and anionic counterparts. In (I), the [SiF6]2- anion is centrosymmetric, with the Si atom occupying a crystallographic centre of inversion (Fig. 1). Each of the 2-carboxypyridinium cations provides pair of strong directional hydrogen bonds (N—H···F and O—H···F) (Table 2). This is a second known example of direct hydrogen bonding of a carboxylic group to [SiF6]2-: the O···F separations in (I) and in the N-carboxymethyl-N-methylpiperidinium salt (2.58 and 2.56 Å, respectively; Szafran et al., 2001) are similar. Thus, the [SiF6]2- anion accepts (in total) two pairs of such interactions utilizing four F atoms, which are coplanar within the coordination octahedron. Therefore, the primary strong hydrogen-bond connectivity in the structure may be considered as a plane (4,4) net, with [SiF6]2- moieties providing four-connected net nodes and with the organic cations as simple links between them (Fig. 2). Such a principle is comparable with the eight-connected framework topology of tetrakis(2-carboxypyridinium)octacyanomolybdate(IV) (Basson et al., 1980) and this suggests the utility of the bifunctional organic cations in the design of hydrogen-bonded frameworks, in combination with suitable counter-anions as geometrically rigid acceptors of hydrogen bonds.
Corrugated hydrogen-bonded layers of (I) are parallel to the [101] plane and they pack with a set of weaker interlayer interactions (Fig. 3), such as C—H···F hydrogen bonding (C···F 3.14–3.18 Å; Table 2) and a weak slipped π–π interaction that occurs between a pair of antiparallel organic moieties related by inversion (symmetry code: 1 - x, 2 - y, -z). The parameters of such interactions, i.e. the interplanar and intercentroid distances [3.347 (2) and 3.626 (1) Å, respectively] and the slippage angle [22.6 (1)°], are typical for π–π contacts between electron-deficient heteroaromatic rings (Janiak, 2000).
In the quinolinium salt, (II), the Si atom of the anion resides on an inversion centre (Fig. 4). The structure is more complicated due to the incorporation of water molecules, which provide additional donor and acceptor sites for strong hydrogen bonding. This is a first structure involving simple 2-carboxyquinolinium cations, since in the previously reported salts of 3-carboxy-4-hydroxybenzenesulfonate (Smith et al., 2004), iodocuprate (Goher et al., 2001) and tetrabromoaurate (Goher et al., 1994), the 2-carboxyquinolinium cations are typically associated by strong O—H···O hydrogen bonding with neutral zwitterionic quinolinium-2-carboxylate moieties.
The carboxyl group of (II) donates a strong hydrogen bond to the O atom of the water molecule (Table 4), while the N—H function interacts directly with the [SiF6]2- anions, similar to (I). This situation parallels the hydrogen-bonding preferences of the anion in 4-carboxyanilinium hexafluorosilicate hydrate (Gelmboldt et al., 2004), while in a simpler hydrated quinolinium salt, the cation···anion interaction was extended by inclusion of water molecules (N—H···OH2···F; Conley et al., 2002). Here, the incorporation of water molecules indicates a lack of convenient hydrogen-bond donors for the quinolinium/[SiF6]2- system in (II).
The water molecules of (II) form pairs of O—H···F bonds with the anions [O···F = 2.6707 (13) and 2.7070 (13) Å], in a very characteristic manner found for aqua–anion dimers (Domasevitch & Boldog, 2005). This generates aqua···anion chains along the a axis direction in the crystal structure (Fig. 5) and the organic cations connect these chains into a three-dimensional framework as simple bitopic connectors (through using O—H and N—H functions). Thus, either F atom of the anions accepts one strong hydrogen bond and the water molecule participates in three such interactions as an acceptor of one and donor of two bonds. Therefore, the entire hydrogen-bonded structure exists as a three-dimensional heterocoordinated framework constituted with three- (water molecules) and six-connected ([SiF6]2- anions) nodes in the ratio 2:1 [total Schlafli symbol {4;62}2{42;610;83}] (Fig. 6). Such topology is commonly related to the heterocoordinated rutile net (rtl) (O'Keeffe et al., 2000).
There are weaker hydrogen bonds involving the aromatic C—H groups of (II), in particular the C9—H9 group directed towards the F1/F2/F3 triangular edge of the [SiF6] octahedron, forming a trifurcated hydrogen bond (Fig. 4). Stacking interactions are also of significance for the crystal packing. These occur between the carbocyclic ring of the cation and two carboxylic acid groups situated on both axial sides (Fig. 7). Atoms O1v and O2vi [symmetry codes: (v) 1/2 - x, y - 1/2, 1/2 - z; (vi) -1/2 - x, y - 1/2, 1/2 - z] are situated almost exactly above the ring centroid with relatively short O···centroid distances (3.22 and 3.30 Å) (Table 5). Such stacking may be compared with recently documented examples of anion (heteroatom)···π interactions, which are characteristic for the most electron-deficient systems of 1,2,4,5-tetrazine (Schottel et al., 2006) and 1,3,5-triazine (Maheswari et al., 2006) [F(O)···π = 2.80–3.20 Å].
In both structures, the organic cations adopt a planar structure [O1—C1—C2—N1 torsion angles do not exceed -3.3 (2)°], with trans-orientation of the O—H and N—H groups. The geometric parameters agree well with those of the 2-carboxypyridinium (Smith et al., 1995) and 2-carboxyquinolinium salts (Goher et al., 2001).
The geometry of the [SiF6]2- anion is sensitive to H···F hydrogen bonding and strong interactions effect an elongation of some Si—F bonds. This is observed in (I) and involves a set of three main bond types, O—H···F3, N—H···F1 and C—H···F2, with a longest Si—F separation corresponding to the F atom interacting with the strongest hydrogen-bond donor [Si—F3 1.7003 (9) Å; Table 1]. For (II), there is no such evident differentiation in the strength of the primary hydrogen bonding (N—H···F and O—H···F with water molecules) and all three unique Si—F separations are similar (Table 3).
In conclusion, both 2-carboxypyridinium and 2-carboxyquinolinium cations reveal potential as singly charged donors of two strong hydrogen bonds and, in combination with [SiF6]2-, they support two and three-dimensional framework topologies.