organic compounds
4-Methylanilinium tetrafluoroborate 18-crown-6 clathrate
aOrdered Matter Science Research Center, College of Chemistry and Chemical, Engineering, Southeast University, Nanjing 211189, People's Republic of China
*Correspondence e-mail: gjz@seu.edu.cn
In the title compound, C7H10N+·BF4−·C12H24O6, the protonated 4-methylanilinium cation interacts with 18-crown-6 forming a rotator–stator structure, (C6H4CH3NH3+)(18-crown-6), through three bifurcated N—H⋯(O,O) hydrogen bonds between the ammonium groups of the cations (–NH3) and the O atoms of the crown ether molecule. The BF4− anions, the methyl group and the protonated –NH3 groups of the 4-methylanilinium lie on a dual axis of rotation. The 18-crown-6 unit is perpendicular to the dual axis of rotation and the mirror plane which contains the dual axis of rotation. The benzene ring of 4-methylanilinium is perpendicular to the mirror plane and parallel to the dual axis.
Related literature
For a similar 18-crown-6 clathrate, see: Pedersen et al. (1967). For ferroelectric properties, see: Fu et al. (2007); Ye et al. (2009).; Zhang et al. (2009).
Experimental
Crystal data
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Refinement
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Data collection: CrystalClear (Rigaku, 2005); cell CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: PRPKAPPA (Ferguson, 1999).
Supporting information
https://doi.org/10.1107/S1600536810019033/jh2160sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810019033/jh2160Isup2.hkl
4-methylaniline(2 mmol, 0.214 g) and excessive tetrafluoroborate (4 mmol, 0.348 g) were dissolved in methanol solution. Then 18-crown-6 (2 mmol, 0.528 g) was added to the mixture. The precipitate was filtered and washed with a small amount of methanol. Single crystals suitable for X-ray
were obtained from slow evaporation of methanol solution at room temperature after two days.All the C—H hydrogen atoms were calculated geometrically and with C—H distances ranging from 0.93 to 0.97 Å and were allowed to ride on the C and O atoms to which they are bonded. With which Uiso(H) = 1.2Ueq(C).
The
were of a great interest since their discovery had been reported by Pedersen (Pedersen et al. 1967). The ability of these macrocycles to form non-covalent,H-bonding complexes with ammonium cations has been actively investigated. Both the size of the crown ether and the nature of the ammonium cation (-NH4+, RNH3+, etc) can influence on the stoichiometry and stability of these host-guest complexes. The host molecules combine with the guest species by intermolecular interaction, and if the host molecule possess some specific sites, it is easy to realise high selectivity in ion or molecular recognitions.18-crown-6 have the highest affinity for ammonium cation RNH3+, while most studies of 18-crown-6 and its derivatives invariably showed a 1:1 stoichiometry with RNH3+ cations.The title compound dielectric permittivity is tested to systematically investigate the ferroelectric phase transitions materials (Fu et al. 2007; Ye et al. 2009; Zhang et al. 2009). The title compound have no dielectric anomalies with the value of 4-5 and 6-8 under 1M Hz in the temperature from 80 to 300 K and 300 to 473 K (the compound m.p.> 473 K), respectively, suggesting that the compound should be no distinct
occurred within the measured temperature range.The the title compound is composed of cationic [(C6H4CH3NH3) (18-Crown-6)]+ and one isolated anionic [BF4]- (Fig 1). The protonated 4-methylaniline [C6H4CH3NH3]+ and 18-crown-6 form superamolecular rotator-stator structure by forming hydrogen-bond (N—H···O) between the ammonium moieties of (-NH3+) cations and each of the six oxygen atoms of
The intramolecular N—H···O hydrogen bonding length are within the usual range: 2.887 (4) and 2.960 (2) Å. The crown ring show slight distortion. The six oxygen atoms of the crown ether lie approximately in a plane. The C—N bonds of [C6H4CH3NH3]+ were almost perpendicular to the mean oxygen plane.The typical B—F bond lengths in the tetrahedral coordinate anion [BF4]- are within 1.374 (4)-1.393 (5) Å. The F—B—F bond angles indicate little distortion from a regular tetrahedron [spread of values 107.3 (4)-111.6 (4)°].
Fig. 2 shows a view down the b axis. The couples of head-to-head rotator-stator cations almost paralleling and plumbing the (1 0 1) direction are alternating arranged. The anions [BF4]- inhabit the cave formed by the couples of head-to-head rotator-stator cations. The title compound was stabilized by intramolecular N—H···O hydrogen bonds, but no intermolecular hydrogen bond was observed.
For a similar 18-crown-6 clathrate, see: Pedersen et al. (1967). For ferroelectric properties, see: Fu et al. (2007); Ye et al. (2009).; Zhang et al. (2009).
Data collection: CrystalClear (Rigaku, 2005); cell
CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: PRPKAPPA (Ferguson, 1999).C7H10N+·BF4−·C12H24O6 | F(000) = 976 |
Mr = 459.28 | Dx = 1.301 Mg m−3 |
Orthorhombic, Pnma | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2n | Cell parameters from 2816 reflections |
a = 15.439 (3) Å | θ = 3.1–27.5° |
b = 11.616 (2) Å | µ = 0.11 mm−1 |
c = 13.071 (3) Å | T = 293 K |
V = 2344.2 (8) Å3 | Block, pale yellow |
Z = 4 | 0.20 × 0.20 × 0.20 mm |
Rigaku SCXmini diffractometer | 2816 independent reflections |
Radiation source: fine-focus sealed tube | 1541 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.086 |
Detector resolution: 13.6612 pixels mm-1 | θmax = 27.5°, θmin = 3.1° |
ω scans | h = −20→20 |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005) | k = −15→15 |
Tmin = 0.977, Tmax = 0.977 | l = −16→16 |
23254 measured reflections |
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)] = 0.067 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.209 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0947P)2 + 0.766P] where P = (Fo2 + 2Fc2)/3 |
2816 reflections | (Δ/σ)max < 0.001 |
154 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
C7H10N+·BF4−·C12H24O6 | V = 2344.2 (8) Å3 |
Mr = 459.28 | Z = 4 |
Orthorhombic, Pnma | Mo Kα radiation |
a = 15.439 (3) Å | µ = 0.11 mm−1 |
b = 11.616 (2) Å | T = 293 K |
c = 13.071 (3) Å | 0.20 × 0.20 × 0.20 mm |
Rigaku SCXmini diffractometer | 2816 independent reflections |
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005) | 1541 reflections with I > 2σ(I) |
Tmin = 0.977, Tmax = 0.977 | Rint = 0.086 |
23254 measured reflections |
R[F2 > 2σ(F2)] = 0.067 | 0 restraints |
wR(F2) = 0.209 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.30 e Å−3 |
2816 reflections | Δρmin = −0.23 e Å−3 |
154 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O1 | 0.45735 (17) | 0.2500 | 0.85026 (19) | 0.0531 (7) | |
O2 | 0.39198 (12) | 0.03619 (16) | 0.78258 (14) | 0.0548 (5) | |
O3 | 0.30174 (13) | 0.04501 (16) | 0.59530 (15) | 0.0607 (6) | |
O4 | 0.21893 (18) | 0.2500 | 0.5296 (2) | 0.0630 (8) | |
C5 | 0.4704 (2) | 0.0478 (3) | 0.8399 (2) | 0.0615 (8) | |
H5A | 0.5189 | 0.0592 | 0.7937 | 0.074* | |
H5B | 0.4809 | −0.0217 | 0.8792 | 0.074* | |
C3 | 0.3162 (2) | −0.0608 (2) | 0.6496 (2) | 0.0640 (8) | |
H3A | 0.3188 | −0.1245 | 0.6017 | 0.077* | |
H3B | 0.2689 | −0.0747 | 0.6968 | 0.077* | |
C4 | 0.3988 (2) | −0.0519 (3) | 0.7065 (2) | 0.0617 (8) | |
H4A | 0.4118 | −0.1250 | 0.7390 | 0.074* | |
H4B | 0.4455 | −0.0337 | 0.6596 | 0.074* | |
C2 | 0.2237 (2) | 0.0450 (3) | 0.5374 (3) | 0.0719 (9) | |
H2A | 0.1742 | 0.0476 | 0.5831 | 0.086* | |
H2B | 0.2199 | −0.0249 | 0.4971 | 0.086* | |
C6 | 0.4625 (2) | 0.1481 (2) | 0.9098 (2) | 0.0587 (8) | |
H6A | 0.4109 | 0.1403 | 0.9516 | 0.070* | |
H6B | 0.5124 | 0.1517 | 0.9548 | 0.070* | |
C1 | 0.2230 (2) | 0.1471 (3) | 0.4689 (2) | 0.0770 (10) | |
H1A | 0.2750 | 0.1478 | 0.4273 | 0.092* | |
H1B | 0.1732 | 0.1435 | 0.4236 | 0.092* | |
N1 | 0.29810 (18) | 0.2500 | 0.7297 (2) | 0.0432 (7) | |
H1C | 0.3138 | 0.3222 | 0.7167 | 0.065* | 0.50 |
H1D | 0.2860 | 0.2142 | 0.6712 | 0.065* | 0.50 |
H1E | 0.3412 | 0.2136 | 0.7613 | 0.065* | 0.50 |
C7 | 0.2212 (2) | 0.2500 | 0.7954 (2) | 0.0406 (8) | |
C8 | 0.18519 (19) | 0.1469 (3) | 0.8255 (2) | 0.0566 (7) | |
H8A | 0.2099 | 0.0775 | 0.8054 | 0.068* | |
C10 | 0.0727 (2) | 0.2500 | 0.9169 (3) | 0.0562 (11) | |
C9 | 0.11146 (19) | 0.1480 (3) | 0.8863 (2) | 0.0624 (8) | |
H9A | 0.0874 | 0.0784 | 0.9071 | 0.075* | |
C11 | −0.0088 (3) | 0.2500 | 0.9817 (4) | 0.0863 (15) | |
H11A | −0.0260 | 0.3279 | 0.9954 | 0.129* | 0.50 |
H11B | 0.0023 | 0.2110 | 1.0450 | 0.129* | 0.50 |
H11C | −0.0544 | 0.2111 | 0.9455 | 0.129* | 0.50 |
B1 | 0.3985 (3) | 0.2500 | 0.2064 (4) | 0.0572 (12) | |
F3 | 0.48142 (17) | 0.2500 | 0.1644 (2) | 0.0831 (8) | |
F1 | 0.38646 (15) | 0.1522 (2) | 0.2638 (2) | 0.1101 (8) | |
F2 | 0.3400 (2) | 0.2500 | 0.1254 (2) | 0.0999 (10) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0597 (17) | 0.0518 (15) | 0.0479 (15) | 0.000 | −0.0094 (12) | 0.000 |
O2 | 0.0579 (12) | 0.0441 (10) | 0.0624 (12) | 0.0055 (8) | 0.0011 (9) | −0.0021 (9) |
O3 | 0.0587 (12) | 0.0543 (12) | 0.0692 (13) | −0.0104 (9) | −0.0082 (10) | −0.0084 (10) |
O4 | 0.0669 (19) | 0.080 (2) | 0.0418 (15) | 0.000 | −0.0083 (13) | 0.000 |
C5 | 0.0575 (18) | 0.0592 (18) | 0.0677 (19) | 0.0124 (14) | −0.0051 (15) | 0.0141 (15) |
C3 | 0.074 (2) | 0.0441 (16) | 0.074 (2) | −0.0127 (14) | 0.0129 (16) | −0.0112 (14) |
C4 | 0.071 (2) | 0.0456 (16) | 0.0688 (19) | 0.0061 (14) | 0.0090 (16) | −0.0020 (14) |
C2 | 0.061 (2) | 0.080 (2) | 0.074 (2) | −0.0116 (16) | −0.0106 (17) | −0.0257 (19) |
C6 | 0.0621 (18) | 0.0637 (19) | 0.0503 (15) | 0.0038 (14) | −0.0086 (13) | 0.0117 (15) |
C1 | 0.070 (2) | 0.109 (3) | 0.0524 (17) | −0.0058 (19) | −0.0146 (15) | −0.020 (2) |
N1 | 0.0446 (17) | 0.0441 (16) | 0.0411 (16) | 0.000 | −0.0027 (13) | 0.000 |
C7 | 0.0379 (19) | 0.047 (2) | 0.0374 (18) | 0.000 | −0.0074 (15) | 0.000 |
C8 | 0.0599 (18) | 0.0526 (17) | 0.0574 (17) | −0.0035 (13) | 0.0064 (14) | −0.0007 (13) |
C10 | 0.040 (2) | 0.086 (3) | 0.042 (2) | 0.000 | −0.0028 (17) | 0.000 |
C9 | 0.0597 (19) | 0.068 (2) | 0.0599 (17) | −0.0157 (15) | 0.0048 (14) | 0.0030 (15) |
C11 | 0.067 (3) | 0.122 (4) | 0.070 (3) | 0.000 | 0.009 (3) | 0.000 |
B1 | 0.049 (3) | 0.047 (3) | 0.076 (3) | 0.000 | −0.010 (2) | 0.000 |
F3 | 0.0672 (17) | 0.0736 (18) | 0.109 (2) | 0.000 | 0.0040 (15) | 0.000 |
F1 | 0.1019 (17) | 0.0984 (17) | 0.1301 (18) | −0.0018 (13) | 0.0172 (14) | 0.0433 (15) |
F2 | 0.081 (2) | 0.114 (2) | 0.105 (2) | 0.000 | −0.0178 (17) | 0.000 |
O1—C6i | 1.419 (3) | C1—H1A | 0.9700 |
O1—C6 | 1.419 (3) | C1—H1B | 0.9700 |
O2—C5 | 1.431 (3) | N1—C7 | 1.465 (4) |
O2—C4 | 1.431 (3) | N1—H1C | 0.8900 |
O3—C2 | 1.423 (3) | N1—H1D | 0.8900 |
O3—C3 | 1.436 (4) | N1—H1E | 0.8900 |
O4—C1 | 1.436 (4) | C7—C8 | 1.378 (3) |
O4—C1i | 1.436 (4) | C7—C8i | 1.378 (3) |
C5—C6 | 1.486 (4) | C8—C9 | 1.388 (4) |
C5—H5A | 0.9700 | C8—H8A | 0.9300 |
C5—H5B | 0.9700 | C10—C9i | 1.386 (4) |
C3—C4 | 1.480 (4) | C10—C9 | 1.386 (4) |
C3—H3A | 0.9700 | C10—C11 | 1.517 (6) |
C3—H3B | 0.9700 | C9—H9A | 0.9300 |
C4—H4A | 0.9700 | C11—H11A | 0.9600 |
C4—H4B | 0.9700 | C11—H11B | 0.9600 |
C2—C1 | 1.487 (5) | C11—H11C | 0.9600 |
C2—H2A | 0.9700 | B1—F1 | 1.374 (4) |
C2—H2B | 0.9700 | B1—F1i | 1.374 (4) |
C6—H6A | 0.9700 | B1—F3 | 1.392 (5) |
C6—H6B | 0.9700 | B1—F2 | 1.393 (5) |
C6i—O1—C6 | 113.0 (3) | O4—C1—H1A | 109.8 |
C5—O2—C4 | 111.7 (2) | C2—C1—H1A | 109.8 |
C2—O3—C3 | 113.2 (2) | O4—C1—H1B | 109.8 |
C1—O4—C1i | 112.7 (3) | C2—C1—H1B | 109.8 |
O2—C5—C6 | 109.0 (2) | H1A—C1—H1B | 108.2 |
O2—C5—H5A | 109.9 | C7—N1—H1C | 109.5 |
C6—C5—H5A | 109.9 | C7—N1—H1D | 109.5 |
O2—C5—H5B | 109.9 | H1C—N1—H1D | 109.5 |
C6—C5—H5B | 109.9 | C7—N1—H1E | 109.5 |
H5A—C5—H5B | 108.3 | H1C—N1—H1E | 109.5 |
O3—C3—C4 | 108.8 (2) | H1D—N1—H1E | 109.5 |
O3—C3—H3A | 109.9 | C8—C7—C8i | 120.7 (3) |
C4—C3—H3A | 109.9 | C8—C7—N1 | 119.65 (17) |
O3—C3—H3B | 109.9 | C8i—C7—N1 | 119.65 (17) |
C4—C3—H3B | 109.9 | C7—C8—C9 | 119.1 (3) |
H3A—C3—H3B | 108.3 | C7—C8—H8A | 120.4 |
O2—C4—C3 | 109.6 (2) | C9—C8—H8A | 120.4 |
O2—C4—H4A | 109.7 | C9i—C10—C9 | 117.4 (4) |
C3—C4—H4A | 109.7 | C9i—C10—C11 | 121.28 (18) |
O2—C4—H4B | 109.7 | C9—C10—C11 | 121.28 (18) |
C3—C4—H4B | 109.7 | C10—C9—C8 | 121.8 (3) |
H4A—C4—H4B | 108.2 | C10—C9—H9A | 119.1 |
O3—C2—C1 | 109.0 (3) | C8—C9—H9A | 119.1 |
O3—C2—H2A | 109.9 | C10—C11—H11A | 109.5 |
C1—C2—H2A | 109.9 | C10—C11—H11B | 109.5 |
O3—C2—H2B | 109.9 | H11A—C11—H11B | 109.5 |
C1—C2—H2B | 109.9 | C10—C11—H11C | 109.5 |
H2A—C2—H2B | 108.3 | H11A—C11—H11C | 109.5 |
O1—C6—C5 | 108.7 (2) | H11B—C11—H11C | 109.5 |
O1—C6—H6A | 109.9 | F1—B1—F1i | 111.6 (4) |
C5—C6—H6A | 109.9 | F1—B1—F3 | 109.9 (2) |
O1—C6—H6B | 109.9 | F1i—B1—F3 | 109.9 (2) |
C5—C6—H6B | 109.9 | F1—B1—F2 | 109.1 (3) |
H6A—C6—H6B | 108.3 | F1i—B1—F2 | 109.1 (3) |
O4—C1—C2 | 109.4 (2) | F3—B1—F2 | 107.3 (4) |
Symmetry code: (i) x, −y+1/2, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1C···O2i | 0.89 | 2.21 | 2.958 (2) | 141 |
N1—H1C···O3i | 0.89 | 2.22 | 2.960 (2) | 140 |
N1—H1D···O4 | 0.89 | 2.16 | 2.887 (4) | 138 |
N1—H1D···O3 | 0.89 | 2.22 | 2.960 (2) | 141 |
N1—H1E···O1 | 0.89 | 2.18 | 2.920 (4) | 140 |
N1—H1E···O2 | 0.89 | 2.22 | 2.958 (2) | 140 |
Symmetry code: (i) x, −y+1/2, z. |
Experimental details
Crystal data | |
Chemical formula | C7H10N+·BF4−·C12H24O6 |
Mr | 459.28 |
Crystal system, space group | Orthorhombic, Pnma |
Temperature (K) | 293 |
a, b, c (Å) | 15.439 (3), 11.616 (2), 13.071 (3) |
V (Å3) | 2344.2 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.20 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Rigaku SCXmini diffractometer |
Absorption correction | Multi-scan (CrystalClear; Rigaku, 2005) |
Tmin, Tmax | 0.977, 0.977 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 23254, 2816, 1541 |
Rint | 0.086 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.067, 0.209, 1.02 |
No. of reflections | 2816 |
No. of parameters | 154 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.30, −0.23 |
Computer programs: CrystalClear (Rigaku, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), PRPKAPPA (Ferguson, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1C···O2i | 0.89 | 2.21 | 2.958 (2) | 140.7 |
N1—H1C···O3i | 0.89 | 2.22 | 2.960 (2) | 140.3 |
N1—H1D···O4 | 0.89 | 2.16 | 2.887 (4) | 138.2 |
N1—H1D···O3 | 0.89 | 2.22 | 2.960 (2) | 141.0 |
N1—H1E···O1 | 0.89 | 2.18 | 2.920 (4) | 140.4 |
N1—H1E···O2 | 0.89 | 2.22 | 2.958 (2) | 139.7 |
Symmetry code: (i) x, −y+1/2, z. |
Acknowledgements
The authors thank the start-up projects for Postdoctoral Research Funds of Southeast University (grant No. 1112000047) and the starter fund of Southeast University for financial support to buy the X-ray diffractometer.
References
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The crown ethers were of a great interest since their discovery had been reported by Pedersen (Pedersen et al. 1967). The ability of these macrocycles to form non-covalent,H-bonding complexes with ammonium cations has been actively investigated. Both the size of the crown ether and the nature of the ammonium cation (-NH4+, RNH3+, etc) can influence on the stoichiometry and stability of these host-guest complexes. The host molecules combine with the guest species by intermolecular interaction, and if the host molecule possess some specific sites, it is easy to realise high selectivity in ion or molecular recognitions.18-crown-6 have the highest affinity for ammonium cation RNH3+, while most studies of 18-crown-6 and its derivatives invariably showed a 1:1 stoichiometry with RNH3+ cations.
The title compound dielectric permittivity is tested to systematically investigate the ferroelectric phase transitions materials (Fu et al. 2007; Ye et al. 2009; Zhang et al. 2009). The title compound have no dielectric anomalies with the value of 4-5 and 6-8 under 1M Hz in the temperature from 80 to 300 K and 300 to 473 K (the compound m.p.> 473 K), respectively, suggesting that the compound should be no distinct phase transition occurred within the measured temperature range.
The the title compound is composed of cationic [(C6H4CH3NH3) (18-Crown-6)]+ and one isolated anionic [BF4]- (Fig 1). The protonated 4-methylaniline [C6H4CH3NH3]+ and 18-crown-6 form superamolecular rotator-stator structure by forming hydrogen-bond (N—H···O) between the ammonium moieties of (-NH3+) cations and each of the six oxygen atoms of crown ethers. The intramolecular N—H···O hydrogen bonding length are within the usual range: 2.887 (4) and 2.960 (2) Å. The crown ring show slight distortion. The six oxygen atoms of the crown ether lie approximately in a plane. The C—N bonds of [C6H4CH3NH3]+ were almost perpendicular to the mean oxygen plane.
The typical B—F bond lengths in the tetrahedral coordinate anion [BF4]- are within 1.374 (4)-1.393 (5) Å. The F—B—F bond angles indicate little distortion from a regular tetrahedron [spread of values 107.3 (4)-111.6 (4)°].
Fig. 2 shows a view down the b axis. The couples of head-to-head rotator-stator cations almost paralleling and plumbing the (1 0 1) direction are alternating arranged. The anions [BF4]- inhabit the cave formed by the couples of head-to-head rotator-stator cations. The title compound was stabilized by intramolecular N—H···O hydrogen bonds, but no intermolecular hydrogen bond was observed.