Synthesis and crystal structures of N,2,4,6-tetra­methyl­anilinium tri­fluoro­methane­sulfonate and N-iso­propyl­idene-N,2,4,6-tetra­methyl­anilinium tri­fluoro­methane­sulfonate

Stewart, J.W.; Irons, E.M.; Osorio Abanto, G.; Zeller, M.; Zaleski, C.M.; Predecki, D.P.

doi:10.1107/S2056989024003438

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ISSN: 2056-9890

Volume 80| Part 5| May 2024| Pages 543-549

https://doi.org/10.1107/S2056989024003438

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Synthesis and crystal structures of N,2,4,6-tetramethylanilinium trifluoromethanesulfonate and N-isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate

John W. Stewart,^a Elena M. Irons,^a Giovanna Osorio Abanto,^a Matthias Zeller,^b Curtis M. Zaleski ^a and Daniel P. Predecki ^a ^*

^aDepartment of Chemistry and Biochemistry, Shippensburg University, Shippensburg, PA 17257, USA, and ^bDepartment of Chemistry, Purdue University, West Lafayette, IN 47907, USA
^*Correspondence e-mail: dppred@ship.edu

Edited by G. Ferrence, Illinois State University, USA (Received 19 February 2024; accepted 17 April 2024; online 26 April 2024)

Two 2,4,6-trimethylaniline-based trifuloromethanesulfonate (trifluoromethanesulfonate) salts were synthesized and characterized by single-crystal X-ray diffraction. N,2,4,6-Tetramethylanilinium trifluoromethanesulfonate, [C₁₀H₁₄NH₂⁺][CF₃O₃S⁻] (1), was synthesized via methylation of 2,4,6-trimethylaniline. N-Isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate, [C₁₃H₂₀N⁺][CF₃O₃S⁻] (2), was synthesized in a two-step reaction where the imine, N-isopropylidene-2,4,6-trimethylaniline, was first prepared via a dehydration reaction to form the Schiff base, followed by methylation using methyl trifluoromethanesulfonate to form the iminium ion. In compound 1, both hydrogen bonding and π–π interactions form the main intermolecular interactions. The primary interaction is a strong N—H⋯O hydrogen bond with the oxygen atoms of the trifluoromethanesulfonate anions bonded to the hydrogen atoms of the ammonium nitrogen atom to generate a one-dimensional chain. The [C₁₀H₁₄NH₂⁺] cations form dimers where the benzene rings form a π–π interaction with a parallel-displaced geometry. The separation distance between the calculated centroids of the benzene rings is 3.9129 (8) Å, and the interplanar spacing and ring slippage between the dimers are 3.5156 (5) and 1.718 Å, respectively. For 2, the [C₁₃H₂₀N⁺] cations also form dimers as in 1, but with the benzene rings highly slipped. The distance between the calculated centroids of the benzene rings is 4.8937 (8) Å, and interplanar spacing and ring slippage are 3.3646 (5) and 3.553 Å, respectively. The major intermolecular interactions in 2 are instead a series of weaker C—H⋯O hydrogen bonds [C⋯O distances of 3.1723 (17), 3.3789 (18), and 3.3789 (18) Å], an interaction virtually absent in the structure of 1. Fluorine atoms are not involved in strong directional interactions in either structure.

Keywords: crystal structure; iminium ion; ammonium ion; trifluoromethanesulfonate; trifluoromethanesulfonate; 2–4,6-trimethylaniline; methylation; N,2,4,6-tetramethylanilinium; N-isopropylidene-N,2,4,6-tetramethylanilinium.

CCDC references: 2349130; 2349129

1. Chemical context

Aniline, the simplest aromatic amine, was first isolated by Otto Unverdorben in 1826 by the destruction of indigo dye. Since its discovery, aniline-based compounds have been extensively utilized as precursors to dyestuffs, pharmaceuticals, polymers, explosives, and industrial feedstocks (Travis, 2007 ). Of relevance to this work, N-methylaniline has been used to synthesize a variety of poly-N-methylaniline materials that function as electrodes, batteries, and nanocomposite sorbents to remove metal ions from solution (Lü et al., 2014 ). In addition, N-substituted anilines, including N-methyl-2,4,6-trimethylaniline, have been used in the preparation of α-amino diazoketones, which have been used as precursors in the synthesis of HIV inhibitors (Castoldi et al., 2018 ).

Condensation of aniline with aldehydes and ketones leads to the formation of Schiff bases otherwise known as imines, of which the primary functional group is a carbon–nitrogen double bond (Tsuchimoto et al., 1973 ; Layer, 1963 ). Addition of an extra atom or group to the imine nitrogen leads to the formation of iminium ions. Iminium ions have been identified as versatile intermediates in traditional organic chemistry, such as in the Knoevenagel and Mannich reactions and have also been utilized in the synthesis of natural products and pharmaceuticals (Erkkilä et al., 2007 ; Böhme et al., 1976 ). Herein, we report synthesis and characterization of two anilinium-based triflate salts, N,2,4,6-tetramethylanilinium trifluoromethanesulfonate, [C₁₀H₁₄NH₂⁺][CF₃O₃S⁻] (1), and N-isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate, [C₁₃H₂₀N⁺][CF₃O₃S⁻] (2).

2. Structural commentary

Both compounds 1 and 2 are ionic compounds based on cations of a 2,4,6-trimethylanilinium unit with functionalization of the amine group and the anion trifluoromethanesulfonate (i.e. triflate). For 1, a secondary ammonium ion results from bonds to a 2,4,6-trimethylphenyl ring, a methyl group, and two hydrogen atoms (Fig. 1). The hydrogen atoms of the ammonium nitrogen atom form hydrogen bonds with the oxygen atoms of neighboring triflate anions. For 2, the iminium ion consists of an isopropylidene group (nitrogen atom double bonded to a carbon atom attached to two methyl groups) with a 2,4,6-trimethylphenyl ring and a methyl group also attached to the nitrogen (Fig. 2). As there are no hydrogen atoms on the iminium nitrogen atom, the organic cation of 2 does not form any classical hydrogen bonds. The 2,4,6-trimethylphenyl groups in both 1 and 2, and the isopropylidene group in 2 are, as expected, nearly planar with r.m.s. deviations from planarity (including the nitrogen atom in the defined planes) of only 0.0263, 0.0111 and 0.0200 Å, respectively. In both compounds, the carbon functional groups of the nitrogen atom lie approximately perpendicular to the trimethylphenyl ring (Fig. 3). For 1, the angle between the calculated mean plane of the methyl group (defined as C1, N1 and C10) and the mean plane of the aniline ring (N1 and C1–C6) is 89.71 (9)°, while for 2, the angle between the mean plane of the isopropylidene and methyl groups (C1, N1, and C10–C13) and the mean plane of the aniline ring (N1, C1–C6) is 85.15 (4)° (Table 1).

Table 1
Angle Between the Mean Plane of the Organic Functional Groups and the Mean Plane of the Aniline Ring

Angles were determined with SHELXL (for 1 and 2; Sheldrick, 2015b ) or Mercury (for comparison compounds; Macrae et al., 2020 ).

Compound	Angle (°)	CSD Reference Code	CCDC Deposition Number
N,2,4,6-Tetramethylanilinium trifluoromethanesulfonate (1)	89.71 (9)	This Work
N-Isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate (2)	85.15 (4)	This Work
Dimesitylammonium pentafluorobenzenesulfonate	49.87 and 55.67	HIBFOO	297281
Dimesitylammonium tosylate	49.49 and 52.91	HIBGAB	604748
Oxonium N-(2,6-diphenylphenyl)mesitylammonium bis(pentafluorobenzenesulfonate)	55.19	HIBFUU	297282
(2,4,6-Trimethylphenyl){2-[N-(2,4,6-trimethylphenyl)formamido]ethyl}ammonium chloride	75.48	EDUWAD	878245
(S)-2-{[1-(Mesitylammonio)-3-methylbutan-2-yl]carbamoyl}benzenesulfonate	76.75	QARJUQ	843836
catena-[N⁴,N⁴′,3,3′,5,5′-hexamethyl[1,1′-biphenyl]-4,4′-bis(aminium) hexakis(μ-bromo)dilead(II)]	85.42	CATZEG	2145329
N-Methyl-1-[3-methyl-2-(2,4,6-trimethylphenyl)-2H-indazol-7-yl]-N-(2,4,6-trimethylphenyl)ethan-1-iminium trifluoromethanesulfonate	82.92	JIFFAI	1842546
{2-[(Hydroxy)(methoxy)methylidene]-4-methoxy-N-methyl-4-oxo-N-(2,4,6-trimethylphenyl)butan-1-iminiumato}[tris(pentafluorophenyl)]boron	80.47	RAVBIC	1504471

Figure 1
The single-crystal X-ray structure of N,2,4,6-tetramethylanilinium trifluoromethanesulfonate, [C₁₀H₁₄NH₂⁺] [CF₃O₃S⁻] (1). Displacement ellipsoids are at the 50% probability level. Color scheme: gray – carbon, blue – nitrogen, red – oxygen, yellow – fluorine, orange – sulfur, and white – hydrogen. All figures were generated with the program Mercury (Macrae et al., 2020

Figure 2
The single-crystal X-ray structure of N-methylisopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate, [C₁₃H₂₀N⁺] [CF₃O₃S⁻] (2). See Fig. 1

for additional display details.

Figure 3
The organic functional groups bound to nitrogen atom are approximately orthogonal to the ring of the 2,4,6-trimethylphenyl group for both (a) 1 and (b) 2. For clarity, the hydrogen atoms have been omitted. See Fig. 1

for additional display details.

3. Supramolecular features

The dominant intermolecular forces in 1 consist of strong N—H⋯O hydrogen bonding (Table 2) and π–π stacking interactions (Table 3), while in 2 no classical hydrogen bonds are present and π–π interactions are highly slipped. Instead, interactions in 2 are governed by a series of weak C—H⋯O/F interactions (Table 4; listed H⋯O/F distances are up to 2.70 Å). Similar C—H⋯O interactions are also present in 1 but they are much less pronounced; the C—H⋯O distances and angles indicate that they are more likely dispersion (i.e. van der Waals) interactions rather than weak directional hydrogen bonds. For both compounds, C—H⋯F and C—H⋯π interactions are very weak and not well defined (Tables 2–4 ).

Table 2
Hydrogen-bond geometry (Å, °) for 1

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O1	0.91	1.92	2.7687 (16)	154
N1—H1B⋯O2ⁱ	0.91	1.94	2.7669 (16)	150
C8—H8C⋯O1ⁱⁱ	0.98	2.63	3.453 (2)	142
C8—H8C⋯O3ⁱⁱ	0.98	2.69	3.6438 (19)	164
C8—H8A⋯O3ⁱⁱⁱ	0.98	2.55	3.504 (2)	165
C9—H9A⋯O2ⁱ	0.98	2.63	3.333 (2)	129
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) ; (iii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Table 3
π–π Interactions with parallel-displaced geometry (Å)

Distances determined with PLATON (Spek, 2020).

Compound/cation	Anion	Benzene ring centroid–centroid distance	Interplanar spacing	Slippage	CSD Refcode	CCDC Deposition Number
N,2,4,6-Tetramethylanilinium	CF₃SO₃⁻	3.9129 (8)	3.5156 (5)	1.718	This Work (1)
N-Isopropylidene-N,2,4,6-tetramethylanilinium	CF₃SO₃⁻	4.8937 (8)	3.3646 (5)	3.553	This Work (2)
1,3,5-Trimethylbenzene		4.6343 (9)	3.0727 (5)	2.850	SOPLAL01	618820^a
2,4,6-Trimethylanilinium	SO₄²⁻	4.486 (2)	3.3028 (14)	2.434	AZUTOF	850619^b
2,4,6-Trimethylanilinium	SO₄²⁻	4.489 (3)	3.2917 (16)	2.459	AZUTOF01	733935^c
2,4,6-Trimethylanilinium	Br⁻	5.362 (3)	3.3138 (18)	3.886	CUCTOK	750635^d
2,4,6-Trimethylanilinium	I⁻	5.5497 (14)	3.4087	4.379	JEVPUW	636623^e
2,4,6-Trimethylanilinium	Cl⁻	4.8109 (17)	3.4992 (9)	3.302	XIFQAF	654863^f
2,4,6-Trimethylanilinium	NO₃⁻	5.3297 (17)	3.0222 (7)	3.928	YUKNUO	734678^g
2,4,6-Trimethylanilinium	ClO₄⁻	5.374 (2)	3.6118 (8)	3.980	YUKPAW	734679^g
2,4,6-Trimethylanilinium	ClO₄⁻	5.526 (11)	3.958 (10)	3.857	YUKPAW01	865148^h
2,4,6-Trimethylanilinium	ClO₄⁻	5.340 (3)	3.6060 (17)	3.939	YUKPAW02	865149^h
References: (a) Ibberson et al. (2007); (b) Rong (2011 ); (c) Kapoor et al. (2010a ); (d) Cui & Xu (2009 ); (e) Lemmerer & Billing (2007 ); (f) Long et al. (2007 ); (g) Kapoor et al. (2010b ); (h) Zhang et al. (2012 ).

Table 4
Hydrogen-bond geometry (Å, °) for 2

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C11—H11A⋯O1ⁱ	0.98	2.56	3.477 (2)	155
C12—H12A⋯F2ⁱⁱ	0.98	2.69	3.3859 (18)	129
C13—H13A⋯O1ⁱ	0.98	2.45	3.3789 (18)	159
C13—H13B⋯O2ⁱⁱⁱ	0.98	2.29	3.2377 (18)	162
C13—H13C⋯O3	0.98	2.52	3.1723 (17)	124
Symmetry codes: (i) ; (ii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iii) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ .

For 1, the principal directional interactions are the N—H⋯O hydrogen bonds. Both ammonium hydrogen atoms are hydrogen bonded to an oxygen atom of neighboring triflate anions (Fig. 4; Table 2). One triflate anion is located on either side of the ammonium nitrogen atom. The hydrogen-bonding arrangement leads to a one-dimensional chain that extends in the ac plane and is propagated by the n-glide plane at (x, 0.75, z). In addition, the organic cations form dimers with the 2,4,6-trimethylphenyl rings arranged in a parallel-displaced geometry where the 2,4,6-trimethylphenyl rings are offset relative to each other. The cations that make up the dimers are symmetry-related by inversion so that the ammonium groups are opposite of each other, likely to avoid Coulombic repulsions (Fig. 5). The distance between the calculated centroids of the benzene rings in each dimer is 3.9129 (8) Å, and the interplanar spacing and ring slippage are 3.5156 (5) and 1.718 Å, respectively [determined with PLATON (Spek, 2020 ); Table 3].

Figure 4
Intermolecular hydrogen bonding in 1 between the ammonium hydrogen atoms and the trifluoromethanesulfonate oxygen atoms. The hydrogen bonding results in a one-dimensional chain that extends in the ac plane. For clarity, only the atoms involved in the hydrogen bonding are labeled. See Fig. 1

for additional display details. [Symmetry code: (i) x + $[{1\over 2}]$ , −y + $[{3\over 2}]$ , z + $[{1\over 2}]$ .]

Figure 5
The organic cations of (a) 1 and (b) 2 form dimers that are related by a crystallographic inversion center and have intermolecular π–π interactions in a parallel-displaced geometry (black dotted lines). See Fig. 1

for additional display details.

In 2, the organic cations also form inversion-related dimers, but the rings are highly slipped (Fig. 5) with respect to each other and π–π interaction, if present at all, is limited to just the outermost atoms C4 and C5. The distance between the calculated centroids of the benzene rings in each dimer is 4.8937 (8) Å, and interplanar spacing and ring slippage are 3.3646 (5) and 3.553 Å, respectively (Table 3). In the absence of classical hydrogen bonding as well as significant π–π interactions, other weak intermolecular forces become dominant in the structure of 2. Most obvious are a series of weaker C—H⋯O interactions (Table 4). Most important are the hydrogen-bond-like interactions that involve the iminium methyl group (C13) being hydrogen bonded to oxygen atoms of three different triflate anions (Fig. 6). This methyl group is directly bonded to the nitrogen atom and carries the largest partial positive charge, inducing formation of charge-assisted bonds that are unusually short for C—H⋯O interactions with C⋯O distances of 3.1723 (17), 3.3789 (18), and 3.3789 (18) Å (Desiraju & Steiner, 2001 ). The isopropylidene methyl group (C11) also does exhibit another unusually short C—H⋯O bond [C⋯O distance of 3.477 (2) Å] (Fig. 6). Each [C₁₃H₂₀N⁺] cation is hydrogen bonded to three triflate anions, and each triflate anion is hydrogen bonded to three organic cations, thereby generating a two-dimensional network of C—H⋯O interactions with layers extending perpendicular to the b-axis direction. The resulting layers interact with each other solely via dispersion interactions.

Figure 6
Intermolecular hydrogen bonding in 2 between the methyl hydrogen atoms of the [C₁₃H₂₀N⁺] cation and the oxygen atoms of three different trifluoromethanesulfonate anions. For clarity, only the hydrogen atoms on the methyl groups involved in the hydrogen bonding are shown and only the atoms involved in the hydrogen bonding are labeled. See Fig. 1

for additional display details. [Symmetry codes: (i) x + 1, y, z; (iii) x + $[{1\over 2}]$ , −y + $[{3\over 2}]$ , z + $[{1\over 2}]$ .]

Both the centroid distance between the benzene rings and the ring slippage distance are longer for 2 than 1. However, the values for 2 are more aligned with the distances for 1,3,5-trimethylbenzene, i.e. mesitylene. In the crystal structure of deuterated-1,3,5-trimethylbenzene (SOPLAL01; Ibberson et al., 2007 ) the molecules also form long π–π interactions with a parallel-displaced geometry, and the distance between the calculated centroids of neighboring benzene rings is 4.634 Å with a ring slippage of 2.850 Å (Table 3). Moreover, the longer distances of 2 are comparable to the centroid and ring slippage distances for a series of 2,4,6-trimethylanilinium cations with various counter-anions (Table 3).

4. Database survey

A survey of the Cambridge Structural Database (CSD version 5.45, update November 2023; Groom et al., 2016 ) for secondary ammonium cations with a 2,4,6-trimethylphenyl group, as in 1, yielded five entries (EDUWAD, HIBFOO, HIBFUU, HIBGAB and QARJUQ). Two of the cations have two 2,4,6-trimethylphenyl groups bound to the ammonium nitrogen atom but with different counter-anions, pentafluorobenzenesulfonate (HIBFOO; Sakakura et al., 2007 ) or 4-methylbenzenesulfonate (HIBGAB; Sakakura et al., 2007). A related secondary ammonium cation binds to one 2,4,6-trimethylphenyl group and one 2,6-diphenylphenyl group and the counter-anion is a pentafluorobenzenesulfonate (HIBFUU; Sakakura et al., 2007). The last two entries also only contain one 2,4,6-trimethylphenyl group on the ammonium nitrogen atom. In one structure (EDUWAD; Ikhile & Bala, 2012 ), an ethyl-2-formamido-2,4,6-trimethylbenzene group is bound to the ammonium nitrogen atom and chloride serves as the counter-anion. The other structure (QARJUQ; Latham et al., 2012 ) is a zwitterion with a 3-methylbutan-2-yl-carbamoylbenzenesulfonate acting as the second group bound to the ammonium nitrogen atom. Lastly, a biphenyl system with two secondary ammonium nitrogen atoms (CATZEG; Li et al., 2022 ) is similar to 1. As in 1, the 1,1′ biphenyl system has an ammonium nitrogen attached to the carbon atom in the 4 and 4′ positions of the benzene rings and on each benzene ring two methyl groups are located on carbon atoms adjacent (3,3′ and 5,5′ positions, respectively) to the carbon atom with the ammonium nitrogen atom. In addition, the ammonium nitrogen atoms bind to a methyl group as in 1. A comparison of the angle between the mean planes of the functional groups and of the aniline ring reveal that the angles generally do not approach 90° as in 1 (Table 1; the angles were measured between mean planes defined in a similar manner as for 1 in the Structural commentary section). The angles range from ca 50 to 77° for the five structures with a 2,4,6-trimethylphenyl group attached to the ammonium nitrogen atom. For these structures, the bulkiness of the groups opposite the 2,4,6-trimethylphenyl groups may prevent the angle being close to 90°. In 1, the group opposite to the 2,4,6-trimethylphenyl group is a smaller methyl group. For the 1,1′-biphenyl system (CATZEG) the angle (ca 85°) is closer to 90° likely due to the two phenyl rings nearly lying in the same plane and the presence of a smaller methyl group.

A survey for compounds containing an iminium nitrogen atom with a 2,4,6-trimethylphenyl ring and with a double-bonded carbon atom bound to two additional carbon groups yielded only one entry (JIFFAI; Kremláček et al., 2018 ). Like 2, the iminium nitrogen atom is bound to a methyl group and a 2,4,6-trimethylphenyl group and the counter-anion is triflate. Unlike 2, substitution on the carbon atom of the iminium double bond consists of a methyl group and a bulky 3-methyl-2-(2,4,6-trimethylphenyl)-2H-indazol-7-yl group. Comparison of the equivalent angle between the mean planes of the functional groups and the aniline ring to that of 2 reveals that the angle (ca 83°) deviates more from 90° than that of 2 (Table 1). In a related structure (RAVBIC; Chen et al., 2017 ), substitution on the carbon atom of the iminium double bond consists of a hydrogen atom and a {2-[(hydroxyl)(methoxy)methylidene]-4-methoxy-4-oxo}{[tris(pentafluorophenyl)]boron} group. In addition, the iminium nitrogen is bound to a methyl group. Also, this compound is a zwitterion instead of a triflate salt with the borate providing the negative charge. In regard to the angle between the mean planes of the functional groups and the aniline ring, there is an even larger deviation (ca 80°), likely due to the bulky {2-[(hydroxyl)(methoxy)methylidene]-4-methoxy-4-oxo}{[tris(pentafluorophenyl)]boron} group (Table 1).

5. Synthesis and crystallization

Synthetic Materials

Methyl trifluoromethanesulfonate (98%) and 4 Å molecular sieves (8–12 mesh) were purchased from Sigma-Aldrich. Anhydrous diethyl ether (99%, ACS Grade) and 2,4,6-trimethylaniline (97%) were purchased from Thermo Scientific. Acetonitile-d₃ (99 atom %D) was purchased from Acros Organics. Chloroform (99.5%) was purchased from Fisher Scientific. Acetone (99.5%) was purchased from VWR Chemicals. Chloroform was dried over 4 Å molecular sieves (8–12 mesh) prior to use. All other chemicals were used as received and without further purification.

N,2,4,6-tetramethylanilinium trifluoromethanesulfonate (1) (29.2%). Dried chloroform (2.0 mL), methyl trifluoromethanesulfonate (0.290 mL, 2.4 mmol, 1.1 eq) and a stir bar were added to a dry 10 mL round-bottom flask flushed with nitrogen gas. 2,4,5-trimethylaniline (0.3200 g, 2.4 mmol, 1 eq) was dissolved in 1.0 mL of dried chloroform and added dropwise to the flask with stirring over ice with the resulting solution appearing clear and colorless. The flask was allowed to stir for 15 min over ice and an additional 30 min at room temperature. House vacuum was then used to remove the solvent, leaving behind an off-white powder. The powder was redissolved in 1–2 mL of dried chloroform with 10 drops of anhydrous diethyl ether. Clear, colorless crystals were grown in 1–2 days by slow evaporation of the solvent at room temperature. The clear crystals (0.2090 g, 29.2%) were vacuum filtered and washed with 5.0 mL of anhydrous diethyl ether. A portion of the crystals were separated for X-ray diffraction analysis with the remaining sample being analyzed as follows: m.p. 429.2–430.5 K; IR (ATR) ν_max 3082 cm⁻¹ (N⁺—H stretch), 1610 cm⁻¹ (N⁺—H bend); ¹H-NMR (CD₃CN, 80 MHz): δ 2.29 (s, 3 H), 2.40 (s, 6 H), 3.02 (t, J = 2.83 Hz, 3 H), 7.04 (s, 1 H); ¹³C{1H}-NMR (CD₃CN, 80 MHz): δ 17.24, 20.68, 37.43, 131.50, 131.76, 132.18, 140.84.

N-isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate (2) (20.7% over two steps). Synthesis was carried out using a two-step process. In step one, N-isopropylidene-2,4,6-trimethylaniline was synthesized utilizing the procedure published by Tsuchimoto et al. (1973). Anhydrous diethyl ether (35.1 mL) was added to a 60 mL amber glass bottle followed by 2,4,6-trimethylaniline (1.5241 g, 11.3 mmol, 1 eq), acetone (1.00 mL, 13.6 mmol, 1.2 eq), and 4 Å molecular sieves (15.6 g) resulting in a clear, slightly brown solution. The bottle was moved to the fridge and reaction progress was monitored by observing the disappearance of the 2,4,6-trimethylaniline peaks by ¹H-NMR. After about 4 days, the sieves were removed by gravity filtration and washed with three 10 mL portions of anhydrous diethyl ether. The resulting solution was rotary evaporated yielding a clear, colorless oil (1.4867 g, 75.3%). The oil was purified by fractional short path vacuum distillation (338.8–340.3 K at 1 mm Hg) to yield three clear liquid fractions, with the second fraction (0.4686 g, 23.7% post-distillation) being used in the next step. IR (ATR) v_max 1670 cm⁻¹ (C=N stretch); ¹H-NMR (CD₃CN, 80MHz): δ 1.58 (s, 3 H), 1.90 (s, 6 H), 2.15 (s, 3 H), 2.21 (s, 3 H), 6.82 (s, 2 H); ¹³C{1H}-NMR (CD₃CN, 80 MHz): δ 17.98, 20.86, 27.73, 126.61, 129.33, 132.33, 147.69, 169.49.

In step two, dried chloroform (2.0 mL), methyl trifluoromethanesulfonate (0.324 mL, 2.9 mmol, 1.1 eq) and a stir bar were added to a dry 10 mL round-bottom flask flushed with nitrogen. N-isopropylidene-2,4,6-trimethylaniline (0.4686 g, 2.7 mmol, 1 eq) was dissolved in dried chloroform (1 mL) and added dropwise to the flask with stirring over ice resulting a clear and colorless solution. The flask was allowed to stir for 15 min over ice and an additional 30 min at room temperature. Upon completion, house vacuum was used to remove the solvent, leaving behind an off-white powder. The powder was then redissolved in 1–2 mL of dried chloroform with 10 drops of anhydrous diethyl ether. White crystals were grown in 1–2 days by slow evaporation of the solvent at room temperature. The white crystals (0.7931 g, 87.4%) were vacuum filtered and washed with 5.0 mL of anhydrous diethyl ether. A portion of the crystals were separated for X-ray diffraction analysis with the remaining sample being analyzed as follows: m.p. 359.0–360.4 K; IR (ATR) ν_max 1648 cm⁻¹ (C=N stretch); ¹H-NMR (CD₃CN, 80 MHz): δ 2.16 (s, 6 H), 2.25 (s, 3 H), 2.33 (s, 3 H), 2.74 (s, 3 H), 3.77 (s, 3 H), 7.12 (s, 2 H); ¹³C{1H}-NMR (CD₃CN, 80 MHz): δ 16.98, 20.81, 24.93, 26.09, 45.42, 131.01, 131.90, 141.50, 196.51.

Physical Methods

The ¹H and ¹³C chemical shifts were reported in ppm (δ) and referenced to CD₃CN. All NMR spectra were recorded at 299.7 K on a Magritek Spinsolve 80 (Malvern, PA USA). Proton and carbon spectra were operated at 80.98 MHz and 20.36 MHz, respectively, with a field strength of 1.88 Tesla. Spectra were processed using MNova software Ver. 14.3.3 (Mestrelab Research, Escondido, CA USA). Infrared spectroscopy was performed using a Nicolet iS5 FTIR spectrometer (Thermo Electron North America LLC) outfitted with a diamond crystal ATR accessory and Omnic software Omnic version 9.2.98.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 5. Hydrogen atoms were placed in calculated positions and refined as riding on their carrier atoms with C—H distances of 0.95 Å for sp² carbon atoms, 0.98 Å for methyl carbon atoms, and 0.91 Å for ammonium nitrogen atoms. Methyl hydrogen atoms were allowed to rotate but not to tip to best fit the experimental electron density. The U_iso values for hydrogen atoms were set to a multiple of the value of the carrying carbon atom or nitrogen atom (1.2 times for sp²-hybridized carbon atoms and the nitrogen atom or 1.5 times for methyl carbon atoms).

Table 5
Experimental details

	1	2
Crystal data
Chemical formula	[C₁₀H₁₆N⁺][CF₃O₃S⁻]	[C₁₃H₂₀N⁺][CF₃O₃S⁻]
M_r	299.31	339.37
Crystal system, space group	Monoclinic, P2₁/n	Monoclinic, P2₁/n
Temperature (K)	150	150
a, b, c (Å)	8.5194 (7), 18.1257 (13), 9.0875 (8)	6.8580 (4), 19.4619 (12), 12.6131 (7)
β (°)	105.106 (3)	102.024 (2)
V (Å³)	1354.80 (19)	1646.53 (17)
Z	4	4
Radiation type	Mo Kα	Mo Kα
μ (mm⁻¹)	0.28	0.24
Crystal size (mm)	0.45 × 0.43 × 0.21	0.45 × 0.43 × 0.32

Data collection
Diffractometer	Bruker AXS D8 Quest	Bruker AXS D8 Quest
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )	Multi-scan (SADABS; Krause et al., 2015)
T_min, T_max	0.559, 0.747	0.662, 0.747
No. of measured, independent and observed [I > 2σ(I)] reflections	47829, 5186, 3572	35093, 6151, 4836
R_int	0.093	0.040
(sin θ/λ)_max (Å⁻¹)	0.772	0.770

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.047, 0.133, 1.03	0.045, 0.136, 1.04
No. of reflections	5186	6151
No. of parameters	176	205
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.42, −0.56	0.63, −0.41
Computer programs: APEX4 and SAINT (Bruker, 2022 ), SHELXT (Sheldrick, 2015a ), SHELXL2019/2 (Sheldrick, 2015b), ShelXle (Hübschle et al., 2011 ), Mercury (Macrae et al., 2020), and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 2349130; 2349129

Crystal structure: contains datablocks 1, 2. DOI: https://doi.org/10.1107/S2056989024003438/ej2004sup1.cif

Structure factors: contains datablock 1. DOI: https://doi.org/10.1107/S2056989024003438/ej20041sup2.hkl

Structure factors: contains datablock 2. DOI: https://doi.org/10.1107/S2056989024003438/ej20042sup3.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989024003438/ej20041sup4.cml

Supporting information file. DOI: https://doi.org/10.1107/S2056989024003438/ej20042sup5.cml

checkCIF report

Computing details top

N,2,4,6-Tetramethylanilinium trifluoromethanesulfonate (1) top

Crystal data top

C₁₀H₁₆N⁺·CF₃O₃S⁻	F(000) = 624
M_r = 299.31	D_x = 1.467 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.5194 (7) Å	Cell parameters from 9989 reflections
b = 18.1257 (13) Å	θ = 2.6–32.7°
c = 9.0875 (8) Å	µ = 0.28 mm⁻¹
β = 105.106 (3)°	T = 150 K
V = 1354.80 (19) Å³	Plate, colourless
Z = 4	0.45 × 0.43 × 0.21 mm

Data collection top

Bruker AXS D8 Quest diffractometer	5186 independent reflections
Radiation source: fine focus sealed tube X-ray source	3572 reflections with I > 2σ(I)
Triumph curved graphite crystal monochromator	R_int = 0.093
Detector resolution: 7.4074 pixels mm^-1	θ_max = 33.3°, θ_min = 2.6°
ω and phi scans	h = −13→12
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	k = −27→27
T_min = 0.559, T_max = 0.747	l = −13→14
47829 measured reflections

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.133	H-atom parameters constrained
S = 1.03	w = 1/[σ²(F_o²) + (0.0667P)² + 0.3108P] where P = (F_o² + 2F_c²)/3
5186 reflections	(Δ/σ)_max = 0.001
176 parameters	Δρ_max = 0.42 e Å⁻³
0 restraints	Δρ_min = −0.56 e Å⁻³

Special details top

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.

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

	x	y	z	U_iso*/U_eq
S1	0.26254 (4)	0.70859 (2)	0.03063 (4)	0.02587 (10)
F1	0.06186 (16)	0.66503 (9)	−0.22410 (12)	0.0730 (4)
F2	−0.00260 (12)	0.62874 (6)	−0.02375 (13)	0.0491 (3)
F3	0.19455 (15)	0.57716 (7)	−0.08796 (18)	0.0703 (4)
O1	0.31540 (15)	0.67224 (7)	0.17559 (12)	0.0431 (3)
O2	0.16299 (15)	0.77239 (7)	0.03049 (17)	0.0469 (3)
O3	0.38537 (14)	0.71728 (7)	−0.04960 (13)	0.0380 (3)
N1	0.38672 (14)	0.64116 (6)	0.48425 (12)	0.0243 (2)
H1A	0.358888	0.636006	0.381079	0.029*
H1B	0.493405	0.654345	0.513906	0.029*
C1	0.36660 (15)	0.56949 (7)	0.55382 (14)	0.0221 (2)
C2	0.24275 (15)	0.52245 (7)	0.47553 (14)	0.0229 (2)
C3	0.21912 (17)	0.45701 (7)	0.54737 (15)	0.0252 (2)
H3	0.136131	0.424047	0.496070	0.030*
C4	0.31396 (16)	0.43847 (7)	0.69272 (15)	0.0252 (3)
C5	0.43919 (16)	0.48619 (8)	0.76333 (14)	0.0257 (3)
H5	0.507495	0.473066	0.860156	0.031*
C6	0.46785 (15)	0.55238 (7)	0.69717 (14)	0.0236 (2)
C7	0.13840 (17)	0.53992 (8)	0.31822 (15)	0.0282 (3)
H7A	0.204815	0.537779	0.245017	0.042*
H7B	0.092515	0.589532	0.317709	0.042*
H7C	0.050034	0.503828	0.289669	0.042*
C8	0.27871 (19)	0.37021 (8)	0.77291 (17)	0.0318 (3)
H8A	0.219874	0.334557	0.697413	0.048*
H8B	0.212107	0.383332	0.842138	0.048*
H8C	0.381199	0.348317	0.831371	0.048*
C9	0.60280 (17)	0.60290 (8)	0.77978 (16)	0.0305 (3)
H9A	0.673863	0.614143	0.713537	0.046*
H9B	0.666105	0.578630	0.872717	0.046*
H9C	0.556113	0.648773	0.806764	0.046*
C10	0.2861 (2)	0.70206 (8)	0.52615 (18)	0.0338 (3)
H10A	0.304250	0.747882	0.475748	0.051*
H10B	0.317801	0.709186	0.636870	0.051*
H10C	0.170738	0.688743	0.493086	0.051*
C11	0.1221 (2)	0.64161 (10)	−0.08269 (18)	0.0374 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.02667 (16)	0.03106 (18)	0.02113 (15)	0.00514 (13)	0.00846 (11)	0.00329 (12)
F1	0.0665 (8)	0.1198 (12)	0.0243 (5)	−0.0232 (8)	−0.0031 (5)	0.0009 (6)
F2	0.0354 (5)	0.0635 (7)	0.0509 (6)	−0.0111 (5)	0.0155 (4)	−0.0054 (5)
F3	0.0570 (7)	0.0532 (7)	0.1026 (11)	−0.0022 (6)	0.0240 (7)	−0.0397 (7)
O1	0.0452 (6)	0.0557 (7)	0.0246 (5)	−0.0077 (6)	0.0022 (4)	0.0128 (5)
O2	0.0396 (6)	0.0398 (6)	0.0647 (9)	0.0121 (5)	0.0197 (6)	−0.0029 (6)
O3	0.0346 (5)	0.0491 (7)	0.0350 (6)	0.0031 (5)	0.0174 (5)	0.0045 (5)
N1	0.0262 (5)	0.0269 (5)	0.0212 (5)	−0.0026 (4)	0.0084 (4)	−0.0013 (4)
C1	0.0247 (5)	0.0245 (6)	0.0192 (5)	0.0002 (5)	0.0095 (4)	−0.0013 (4)
C2	0.0228 (5)	0.0280 (6)	0.0187 (5)	0.0001 (5)	0.0072 (4)	−0.0007 (4)
C3	0.0277 (6)	0.0268 (6)	0.0226 (5)	−0.0015 (5)	0.0092 (5)	−0.0013 (5)
C4	0.0294 (6)	0.0258 (6)	0.0231 (6)	0.0043 (5)	0.0118 (5)	0.0014 (5)
C5	0.0275 (6)	0.0315 (7)	0.0190 (5)	0.0041 (5)	0.0079 (4)	−0.0001 (5)
C6	0.0236 (5)	0.0300 (6)	0.0185 (5)	0.0014 (5)	0.0076 (4)	−0.0037 (4)
C7	0.0278 (6)	0.0336 (7)	0.0217 (6)	−0.0034 (5)	0.0037 (5)	0.0027 (5)
C8	0.0378 (7)	0.0307 (7)	0.0290 (7)	0.0030 (6)	0.0124 (6)	0.0069 (5)
C9	0.0302 (7)	0.0364 (7)	0.0237 (6)	−0.0027 (6)	0.0049 (5)	−0.0046 (5)
C10	0.0411 (8)	0.0264 (7)	0.0382 (8)	0.0043 (6)	0.0176 (6)	0.0005 (6)
C11	0.0352 (7)	0.0486 (9)	0.0288 (7)	0.0009 (7)	0.0088 (6)	−0.0056 (6)

Geometric parameters (Å, º) top

S1—O3	1.4315 (11)	C4—C5	1.393 (2)
S1—O2	1.4339 (12)	C4—C8	1.5052 (19)
S1—O1	1.4364 (11)	C5—C6	1.3918 (19)
S1—C11	1.8230 (17)	C5—H5	0.9500
F1—C11	1.3234 (19)	C6—C9	1.5080 (19)
F2—C11	1.3293 (19)	C7—H7A	0.9800
F3—C11	1.328 (2)	C7—H7B	0.9800
N1—C1	1.4742 (17)	C7—H7C	0.9800
N1—C10	1.5062 (18)	C8—H8A	0.9800
N1—H1A	0.9100	C8—H8B	0.9800
N1—H1B	0.9100	C8—H8C	0.9800
C1—C6	1.3970 (18)	C9—H9A	0.9800
C1—C2	1.3983 (18)	C9—H9B	0.9800
C2—C3	1.3935 (18)	C9—H9C	0.9800
C2—C7	1.5073 (18)	C10—H10A	0.9800
C3—C4	1.3980 (18)	C10—H10B	0.9800
C3—H3	0.9500	C10—H10C	0.9800

O3—S1—O2	114.93 (8)	C2—C7—H7A	109.5
O3—S1—O1	114.93 (7)	C2—C7—H7B	109.5
O2—S1—O1	114.51 (8)	H7A—C7—H7B	109.5
O3—S1—C11	104.16 (7)	C2—C7—H7C	109.5
O2—S1—C11	103.63 (8)	H7A—C7—H7C	109.5
O1—S1—C11	102.43 (7)	H7B—C7—H7C	109.5
C1—N1—C10	113.57 (10)	C4—C8—H8A	109.5
C1—N1—H1A	108.9	C4—C8—H8B	109.5
C10—N1—H1A	108.9	H8A—C8—H8B	109.5
C1—N1—H1B	108.9	C4—C8—H8C	109.5
C10—N1—H1B	108.9	H8A—C8—H8C	109.5
H1A—N1—H1B	107.7	H8B—C8—H8C	109.5
C6—C1—C2	122.66 (12)	C6—C9—H9A	109.5
C6—C1—N1	118.88 (11)	C6—C9—H9B	109.5
C2—C1—N1	118.41 (11)	H9A—C9—H9B	109.5
C3—C2—C1	117.56 (12)	C6—C9—H9C	109.5
C3—C2—C7	120.11 (12)	H9A—C9—H9C	109.5
C1—C2—C7	122.32 (12)	H9B—C9—H9C	109.5
C2—C3—C4	121.93 (12)	N1—C10—H10A	109.5
C2—C3—H3	119.0	N1—C10—H10B	109.5
C4—C3—H3	119.0	H10A—C10—H10B	109.5
C5—C4—C3	118.07 (12)	N1—C10—H10C	109.5
C5—C4—C8	120.84 (12)	H10A—C10—H10C	109.5
C3—C4—C8	121.06 (13)	H10B—C10—H10C	109.5
C6—C5—C4	122.39 (12)	F1—C11—F3	108.27 (15)
C6—C5—H5	118.8	F1—C11—F2	107.40 (14)
C4—C5—H5	118.8	F3—C11—F2	106.73 (15)
C5—C6—C1	117.33 (12)	F1—C11—S1	111.49 (13)
C5—C6—C9	120.35 (12)	F3—C11—S1	111.33 (12)
C1—C6—C9	122.33 (12)	F2—C11—S1	111.41 (11)

C10—N1—C1—C6	−89.12 (15)	C2—C1—C6—C5	−1.40 (18)
C10—N1—C1—C2	88.69 (14)	N1—C1—C6—C5	176.31 (11)
C6—C1—C2—C3	1.63 (19)	C2—C1—C6—C9	179.04 (12)
N1—C1—C2—C3	−176.09 (11)	N1—C1—C6—C9	−3.25 (18)
C6—C1—C2—C7	−177.50 (12)	O3—S1—C11—F1	−58.65 (14)
N1—C1—C2—C7	4.78 (18)	O2—S1—C11—F1	61.92 (14)
C1—C2—C3—C4	0.40 (19)	O1—S1—C11—F1	−178.71 (12)
C7—C2—C3—C4	179.54 (12)	O3—S1—C11—F3	62.38 (14)
C2—C3—C4—C5	−2.52 (19)	O2—S1—C11—F3	−177.05 (13)
C2—C3—C4—C8	175.57 (12)	O1—S1—C11—F3	−57.68 (14)
C3—C4—C5—C6	2.77 (19)	O3—S1—C11—F2	−178.61 (11)
C8—C4—C5—C6	−175.32 (12)	O2—S1—C11—F2	−58.04 (14)
C4—C5—C6—C1	−0.87 (19)	O1—S1—C11—F2	61.33 (13)
C4—C5—C6—C9	178.69 (12)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1	0.91	1.92	2.7687 (16)	154
N1—H1B···O2ⁱ	0.91	1.94	2.7669 (16)	150
C8—H8C···O1ⁱⁱ	0.98	2.63	3.453 (2)	142
C8—H8C···O3ⁱⁱ	0.98	2.69	3.6438 (19)	164
C8—H8A···O3ⁱⁱⁱ	0.98	2.55	3.504 (2)	165
C9—H9A···O2ⁱ	0.98	2.63	3.333 (2)	129

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

N-Isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate (2) top

Crystal data top

C₁₃H₂₀N⁺·CF₃O₃S⁻	F(000) = 712
M_r = 339.37	D_x = 1.369 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.8580 (4) Å	Cell parameters from 9901 reflections
b = 19.4619 (12) Å	θ = 2.7–33.1°
c = 12.6131 (7) Å	µ = 0.24 mm⁻¹
β = 102.024 (2)°	T = 150 K
V = 1646.53 (17) Å³	Block, colourless
Z = 4	0.45 × 0.43 × 0.32 mm

Data collection top

Bruker AXS D8 Quest diffractometer	6151 independent reflections
Radiation source: fine focus sealed tube X-ray source	4836 reflections with I > 2σ(I)
Triumph curved graphite crystal monochromator	R_int = 0.040
Detector resolution: 7.4074 pixels mm^-1	θ_max = 33.2°, θ_min = 2.0°
ω and phi scans	h = −10→10
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	k = −29→28
T_min = 0.662, T_max = 0.747	l = −19→19
35093 measured reflections

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.045	H-atom parameters constrained
wR(F²) = 0.136	w = 1/[σ²(F_o²) + (0.0647P)² + 0.6525P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.036
6151 reflections	Δρ_max = 0.63 e Å⁻³
205 parameters	Δρ_min = −0.41 e Å⁻³

Special details top

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

	x	y	z	U_iso*/U_eq
S1	0.15479 (4)	0.79780 (2)	0.61391 (2)	0.02550 (8)
F1	0.3761 (3)	0.86287 (8)	0.77561 (9)	0.0851 (5)
F2	0.2530 (2)	0.92744 (5)	0.64188 (11)	0.0664 (3)
F3	0.49502 (18)	0.86146 (8)	0.63158 (12)	0.0734 (4)
O1	−0.02107 (18)	0.81355 (7)	0.65353 (12)	0.0494 (3)
O2	0.1341 (2)	0.80438 (7)	0.49895 (9)	0.0507 (3)
O3	0.25615 (18)	0.73657 (6)	0.66054 (11)	0.0496 (3)
N1	0.86535 (15)	0.64144 (5)	0.77099 (8)	0.02325 (18)
C1	0.81204 (17)	0.57568 (6)	0.71732 (9)	0.0235 (2)
C2	0.73919 (18)	0.52358 (6)	0.77498 (10)	0.0266 (2)
C3	0.68216 (19)	0.46217 (6)	0.72058 (12)	0.0310 (3)
H3	0.631492	0.426053	0.757740	0.037*
C4	0.69727 (19)	0.45226 (7)	0.61361 (12)	0.0318 (3)
C5	0.7696 (2)	0.50569 (7)	0.55946 (11)	0.0320 (3)
H5	0.779749	0.499239	0.486153	0.038*
C6	0.82752 (19)	0.56836 (6)	0.60949 (10)	0.0269 (2)
C7	0.7275 (2)	0.53217 (8)	0.89215 (12)	0.0370 (3)
H7A	0.675490	0.577958	0.903002	0.055*
H7B	0.860854	0.526986	0.937972	0.055*
H7C	0.638530	0.497155	0.911733	0.055*
C8	0.6377 (2)	0.38445 (8)	0.55818 (16)	0.0450 (4)
H8A	0.613907	0.390669	0.479424	0.067*
H8B	0.515577	0.367745	0.578344	0.067*
H8C	0.744876	0.350912	0.580769	0.067*
C9	0.9047 (2)	0.62569 (7)	0.54963 (12)	0.0365 (3)
H9A	0.898812	0.611766	0.474357	0.055*
H9B	1.043117	0.635892	0.584635	0.055*
H9C	0.822601	0.666766	0.550892	0.055*
C10	1.03905 (18)	0.65257 (6)	0.83181 (10)	0.0274 (2)
C11	1.0819 (2)	0.71841 (7)	0.89199 (12)	0.0368 (3)
H11A	1.071297	0.756521	0.840322	0.055*
H11B	1.217001	0.717058	0.936743	0.055*
H11C	0.985468	0.725038	0.938559	0.055*
C12	1.2004 (2)	0.60056 (8)	0.84344 (15)	0.0411 (3)
H12A	1.148345	0.558503	0.805015	0.062*
H12B	1.249569	0.590234	0.920420	0.062*
H12C	1.309884	0.618616	0.812571	0.062*
C13	0.70636 (19)	0.69461 (6)	0.75334 (11)	0.0293 (2)
H13A	0.758175	0.737207	0.728243	0.044*
H13B	0.663458	0.703278	0.821535	0.044*
H13C	0.592598	0.678426	0.698583	0.044*
C14	0.3300 (3)	0.86552 (8)	0.66949 (12)	0.0387 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.02328 (14)	0.02674 (14)	0.02618 (14)	−0.00154 (10)	0.00446 (10)	−0.00088 (10)
F1	0.1245 (13)	0.0883 (10)	0.0321 (5)	−0.0545 (9)	−0.0077 (6)	−0.0097 (6)
F2	0.0969 (10)	0.0280 (5)	0.0795 (8)	−0.0120 (5)	0.0304 (7)	−0.0050 (5)
F3	0.0431 (6)	0.0875 (9)	0.0941 (10)	−0.0345 (6)	0.0248 (6)	−0.0337 (8)
O1	0.0396 (6)	0.0469 (6)	0.0695 (8)	−0.0009 (5)	0.0291 (6)	−0.0024 (6)
O2	0.0612 (8)	0.0616 (8)	0.0282 (5)	−0.0198 (6)	0.0068 (5)	−0.0046 (5)
O3	0.0405 (6)	0.0309 (5)	0.0708 (8)	0.0043 (4)	−0.0036 (6)	0.0016 (5)
N1	0.0232 (4)	0.0196 (4)	0.0266 (4)	0.0017 (3)	0.0043 (3)	0.0010 (3)
C1	0.0221 (5)	0.0191 (4)	0.0286 (5)	−0.0006 (4)	0.0036 (4)	0.0011 (4)
C2	0.0235 (5)	0.0235 (5)	0.0324 (5)	0.0009 (4)	0.0050 (4)	0.0063 (4)
C3	0.0259 (6)	0.0206 (5)	0.0461 (7)	−0.0013 (4)	0.0063 (5)	0.0071 (5)
C4	0.0265 (6)	0.0204 (5)	0.0466 (7)	−0.0025 (4)	0.0032 (5)	−0.0026 (5)
C5	0.0351 (6)	0.0269 (6)	0.0335 (6)	−0.0043 (5)	0.0062 (5)	−0.0046 (5)
C6	0.0293 (6)	0.0228 (5)	0.0288 (5)	−0.0032 (4)	0.0069 (4)	0.0002 (4)
C7	0.0401 (7)	0.0387 (7)	0.0335 (6)	0.0011 (6)	0.0110 (5)	0.0099 (5)
C8	0.0404 (8)	0.0247 (6)	0.0681 (11)	−0.0077 (5)	0.0073 (7)	−0.0115 (6)
C9	0.0496 (8)	0.0298 (6)	0.0328 (6)	−0.0107 (6)	0.0145 (6)	0.0006 (5)
C10	0.0257 (5)	0.0237 (5)	0.0310 (5)	−0.0004 (4)	0.0022 (4)	0.0016 (4)
C11	0.0405 (7)	0.0300 (6)	0.0367 (6)	−0.0056 (5)	0.0004 (5)	−0.0065 (5)
C12	0.0256 (6)	0.0317 (7)	0.0604 (9)	0.0039 (5)	−0.0042 (6)	0.0033 (6)
C13	0.0266 (6)	0.0253 (5)	0.0360 (6)	0.0076 (4)	0.0066 (5)	0.0024 (4)
C14	0.0479 (8)	0.0345 (7)	0.0344 (6)	−0.0132 (6)	0.0101 (6)	−0.0067 (5)

Geometric parameters (Å, º) top

S1—O1	1.4315 (12)	C7—H7A	0.9800
S1—O2	1.4330 (12)	C7—H7B	0.9800
S1—O3	1.4419 (12)	C7—H7C	0.9800
S1—C14	1.8226 (15)	C8—H8A	0.9800
F1—C14	1.3107 (18)	C8—H8B	0.9800
F2—C14	1.333 (2)	C8—H8C	0.9800
F3—C14	1.319 (2)	C9—H9A	0.9800
N1—C10	1.2937 (16)	C9—H9B	0.9800
N1—C1	1.4584 (15)	C9—H9C	0.9800
N1—C13	1.4860 (15)	C10—C12	1.4843 (18)
C1—C6	1.3934 (17)	C10—C11	1.4871 (18)
C1—C2	1.3994 (16)	C11—H11A	0.9800
C2—C3	1.3929 (18)	C11—H11B	0.9800
C2—C7	1.5060 (19)	C11—H11C	0.9800
C3—C4	1.388 (2)	C12—H12A	0.9800
C3—H3	0.9500	C12—H12B	0.9800
C4—C5	1.3910 (19)	C12—H12C	0.9800
C4—C8	1.5095 (19)	C13—H13A	0.9800
C5—C6	1.3925 (17)	C13—H13B	0.9800
C5—H5	0.9500	C13—H13C	0.9800
C6—C9	1.5039 (18)

O1—S1—O2	114.90 (9)	C4—C8—H8C	109.5
O1—S1—O3	113.84 (8)	H8A—C8—H8C	109.5
O2—S1—O3	115.11 (8)	H8B—C8—H8C	109.5
O1—S1—C14	104.29 (8)	C6—C9—H9A	109.5
O2—S1—C14	104.07 (7)	C6—C9—H9B	109.5
O3—S1—C14	102.57 (8)	H9A—C9—H9B	109.5
C10—N1—C1	122.21 (10)	C6—C9—H9C	109.5
C10—N1—C13	121.91 (11)	H9A—C9—H9C	109.5
C1—N1—C13	115.87 (10)	H9B—C9—H9C	109.5
C6—C1—C2	122.77 (11)	N1—C10—C12	121.33 (12)
C6—C1—N1	118.69 (10)	N1—C10—C11	120.42 (12)
C2—C1—N1	118.47 (11)	C12—C10—C11	118.25 (12)
C3—C2—C1	117.36 (12)	C10—C11—H11A	109.5
C3—C2—C7	120.79 (12)	C10—C11—H11B	109.5
C1—C2—C7	121.83 (12)	H11A—C11—H11B	109.5
C4—C3—C2	121.87 (12)	C10—C11—H11C	109.5
C4—C3—H3	119.1	H11A—C11—H11C	109.5
C2—C3—H3	119.1	H11B—C11—H11C	109.5
C3—C4—C5	118.67 (12)	C10—C12—H12A	109.5
C3—C4—C8	120.26 (13)	C10—C12—H12B	109.5
C5—C4—C8	121.06 (14)	H12A—C12—H12B	109.5
C4—C5—C6	121.98 (12)	C10—C12—H12C	109.5
C4—C5—H5	119.0	H12A—C12—H12C	109.5
C6—C5—H5	119.0	H12B—C12—H12C	109.5
C5—C6—C1	117.34 (11)	N1—C13—H13A	109.5
C5—C6—C9	121.29 (12)	N1—C13—H13B	109.5
C1—C6—C9	121.37 (11)	H13A—C13—H13B	109.5
C2—C7—H7A	109.5	N1—C13—H13C	109.5
C2—C7—H7B	109.5	H13A—C13—H13C	109.5
H7A—C7—H7B	109.5	H13B—C13—H13C	109.5
C2—C7—H7C	109.5	F1—C14—F3	108.99 (16)
H7A—C7—H7C	109.5	F1—C14—F2	107.49 (14)
H7B—C7—H7C	109.5	F3—C14—F2	106.43 (14)
C4—C8—H8A	109.5	F1—C14—S1	111.32 (11)
C4—C8—H8B	109.5	F3—C14—S1	111.33 (11)
H8A—C8—H8B	109.5	F2—C14—S1	111.08 (12)

C10—N1—C1—C6	−97.12 (14)	N1—C1—C6—C5	−178.02 (11)
C13—N1—C1—C6	84.04 (14)	C2—C1—C6—C9	179.42 (13)
C10—N1—C1—C2	85.64 (15)	N1—C1—C6—C9	2.30 (18)
C13—N1—C1—C2	−93.20 (13)	C1—N1—C10—C12	4.98 (19)
C6—C1—C2—C3	0.47 (18)	C13—N1—C10—C12	−176.25 (13)
N1—C1—C2—C3	177.60 (10)	C1—N1—C10—C11	−175.12 (12)
C6—C1—C2—C7	178.81 (12)	C13—N1—C10—C11	3.65 (19)
N1—C1—C2—C7	−4.06 (18)	O1—S1—C14—F1	63.94 (16)
C1—C2—C3—C4	0.35 (19)	O2—S1—C14—F1	−175.28 (14)
C7—C2—C3—C4	−178.00 (12)	O3—S1—C14—F1	−55.02 (16)
C2—C3—C4—C5	−0.7 (2)	O1—S1—C14—F3	−174.22 (13)
C2—C3—C4—C8	178.79 (13)	O2—S1—C14—F3	−53.45 (15)
C3—C4—C5—C6	0.2 (2)	O3—S1—C14—F3	66.82 (14)
C8—C4—C5—C6	−179.25 (13)	O1—S1—C14—F2	−55.81 (13)
C4—C5—C6—C1	0.5 (2)	O2—S1—C14—F2	64.97 (13)
C4—C5—C6—C9	−179.79 (14)	O3—S1—C14—F2	−174.77 (11)
C2—C1—C6—C5	−0.90 (19)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11A···O1ⁱ	0.98	2.56	3.477 (2)	155
C12—H12A···F2ⁱⁱ	0.98	2.69	3.3859 (18)	129
C13—H13A···O1ⁱ	0.98	2.45	3.3789 (18)	159
C13—H13B···O2ⁱⁱⁱ	0.98	2.29	3.2377 (18)	162
C13—H13C···O3	0.98	2.52	3.1723 (17)	124

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

Angle Between the Mean Plane of the Organic Functional Groups and the Mean Plane of the Aniline Ring^§ top

Angles were determined with SHELXL (for 1 and 2; Sheldrick, 2015b) or Mercury [for comparison compounds; Macrae et al., 2020).

Compound	Angle (°)	CSD Reference Code	CCDC Deposition Number
N,2,4,6-Tetramethylanilinium trifluoromethanesulfonate (1)	89.71 (9)	This Work
N-Isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate (2)	85.15 (4)	This Work
Dimesitylammonium pentafluorobenzenesulfonate	49.87 and 55.67	HIBFOO	297281
Dimesitylammonium tosylate	49.49 and 52.91	HIBGAB	604748
Oxonium N-(2,6-diphenylphenyl)mesitylammonium bis(pentafluorobenzenesulfonate)	55.19	HIBFUU	297282
(2,4,6-Trimethylphenyl){2-[N-(2,4,6- trimethylphenyl)formamido]ethyl}ammonium chloride	75.48	EDUWAD	878245
(S)-2-{[1-(Mesitylammonio)-3-methylbutan-2- yl]carbamoyl}benzenesulfonate	76.75	QARJUQ	843836
catena-[N⁴,N⁴',3,3',5,5'-hexamethyl[1,1'-biphenyl]-\ 4,4'-bis(aminium) hexakis(µ-bromo)dilead(II)]	85.42	CATZEG	2145329
N-Methyl-1-[3-methyl-2-(2,4,6-trimethylphenyl)-2H-indazol-7-yl]-N-(2,4,6-trimethylphenyl)ethan-1-iminium trifluoromethanesulfonate	82.92	JIFFAI	1842546
{2-[(Hydroxy)(methoxy)methylidene]-4-methoxy-N-methyl-4-oxo- N-(2,4,6-trimethylphenyl)butan-1-iminiumato}[tris(pentafluorophenyl)]boron	80.47	RAVBIC	1504471

π–π Interactions with parallel-displaced geometry (Å) top

Distances determined with PLATON (Spek, 2020).

Compound/cation	Anion	Benzene ring centroid-centroid distance	Interplanar spacing	Slippage	CSD Reference Code	CCDC Deposition Number
N,2,4,6-Tetramethylanilinium	CF₃SO₃^-	3.9129 (8)	3.5156 (5)	1.718	This Work (1)
N-Isopropylidene-N,2,4,6-tetramethylanilinium	CF₃SO₃^-	4.8937 (8)	3.3646 (5)	3.553	This Work (2)
1,3,5-Trimethylbenzene		4.6343 (9)	3.0727 (5)	2.850	SOPLAL01	618820^a
2,4,6-Trimethylanilinium	SO₄^2-	4.486 (2)	3.3028 (14)	2.434	AZUTOF	850619^b
2,4,6-Trimethylanilinium	SO₄^2-	4.489 (3)	3.2917 (16)	2.459	AZUTOF01	733935^c
2,4,6-Trimethylanilinium	Br^-	5.362 (3)	3.3138 (18)	3.886	CUCTOK	750635^d
2,4,6-Trimethylanilinium	I^-	5.5497 (14)	3.4087	4.379	JEVPUW	636623^e
2,4,6-Trimethylanilinium	Cl^-	4.8109 (17)	3.4992 (9)	3.302	XIFQAF	654863^f
2,4,6-Trimethylanilinium	NO₃^-	5.3297 (17)	3.0222 (7)	3.928	YUKNUO	734678^g
2,4,6-Trimethylanilinium	ClO₄^-	5.374 (2)	3.6118 (8)	3.980	YUKPAW	734679^g
2,4,6-Trimethylanilinium	ClO₄^-	5.526 (11)	3.958 (10)	3.857	YUKPAW01	865148^h
2,4,6-Trimethylanilinium	ClO₄^-	5.340 (3)	3.6060 (17)	3.939	YUKPAW02	865149^h

References: (a) Ibberson et al. (2007); (b) Rong (2011); (c) Kapoor et al. (2010a); (d) Cui & Xu (2009); (e) Lemmerer & Billing (2007); (f) Long et al. (2007); (g) Kapoor et al. (2010b); (h) Zhang et al. (2012).

Acknowledgements

The authors would like thank Dr James Fishbein at the University of Maryland Baltimore County for project insight and Dr Cynthia Day at Wake Forest University for her original X-ray diffraction analysis of N-methylisopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate (2).

Funding information

Funding for this research was provided by: National Science Foundation, Major Research Instrumentation Program (award No. 1625543 to M. Zeller); Shippensburg University Summer Undergraduate Research Experience (SURE) (grant to E. M. Irons, J. W. Stewart, D. P. Predecki); Shippensburg University College of Arts and Sciences Faculty-Led Research Fund (CAS FLRF) (grant to G. Osorio Abanto, D. P. Predecki); Beres Student/Faculty Research Endowment (grant to J. W. Stewart, D. P. Predecki).

References

Böhme, H. & Viehe, H. G. (1976). Advances in Organic Chemistry: Methods and Results Vol. 9, Iminium Salts in Organic Chemistry, Part 2. edited by H. Böhme & H. G. Viehe, pp. 759–773. New York: John Wiley and Sons. Google Scholar
Bruker (2022). APEX4 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Castoldi, L., Ielo, L., Holzer, W., Giester, G., Roller, A. & Pace, V. (2018). J. Org. Chem. 83, 4336–4347. CSD CrossRef CAS PubMed Google Scholar
Chen, G., Kehr, G., Daniliuc, C. G., Bursch, M., Grimme, S. & Erker, G. (2017). Chem. Eur. J. 23, 4723–4729. CSD CrossRef CAS PubMed Google Scholar
Cui, L.-J. & Xu, H.-J. (2009). Acta Cryst. E65, o2376. CSD CrossRef IUCr Journals Google Scholar
Desiraju, G. R. & Steiner, T. (2001). The Weak Hydrogen Bond In Structural Chemistry and Biology. Oxford University Press. Google Scholar
Erkkilä, A., Majander, I. & Pihko, P. M. (2007). Chem. Rev. 107, 5416–5470. PubMed Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Hübschle, C. B., Sheldrick, G. M. & Dittrich, B. (2011). J. Appl. Cryst. 44, 1281–1284. Web of Science CrossRef IUCr Journals Google Scholar
Ibberson, R. M., Parsons, S., Natkaniec, I. & Hołderna-Natkaniec, K. (2007). Z. Kristallogr. Suppl. 2007, 575–580. CSD CrossRef Google Scholar
Ikhile, M. I. & Bala, M. D. (2012). Acta Cryst. E68, o3263. CSD CrossRef IUCr Journals Google Scholar
Kapoor, I. P. S., Kapoor, M., Singh, G. & Frohlich, R. (2010a). Indian J. Eng. Mat. Sci. 17, 305–310. CAS Google Scholar
Kapoor, I. P. S., Kapoor, M., Singh, G., Singh, U. P. & Goel, N. (2010b). J. Hazard. Mater. 173, 173–180. CSD CrossRef PubMed CAS Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef ICSD CAS IUCr Journals Google Scholar
Kremláček, V., Hyvl, J., Yoshida, W. Y., Růžička, A., Rheingold, A. L., Turek, J., Hughes, R. P., Dostál, L. & Cain, M. F. (2018). Organometallics, 37, 2481–2490. Google Scholar
Latham, C. M., Blake, A. J., Lewis, W., Lawrence, M. & Woodward, S. (2012). Eur. J. Org. Chem. pp. 699–707. CSD CrossRef Google Scholar
Layer, R. (1963). Chem. Rev. 63, 489–510. CrossRef CAS Google Scholar
Lemmerer, A. & Billing, D. G. (2007). Acta Cryst. E63, o929–o931. Web of Science CSD CrossRef IUCr Journals Google Scholar
Li, Y., Zheng, R., Fu, Z., Xu, G. & Wang, G. (2022). Inorg. Chem. Commun. 139, 109339. CSD CrossRef ICSD Google Scholar
Long, S., Siegler, M. & Li, T. (2007). Acta Cryst. E63, o3080. Web of Science CSD CrossRef IUCr Journals Google Scholar
Lü, Q., Luo, J., Lin, T. & Zhang, Y. (2014). ACS Sustainable Chem. Eng. 2, 465–471. Google Scholar
Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226–235. Web of Science CrossRef CAS IUCr Journals Google Scholar
Rong, T. (2011). Acta Cryst. E67, o2729. CSD CrossRef IUCr Journals Google Scholar
Sakakura, A., Watanabe, H., Nakagawa, S. & Ishihara, K. (2007). Chem. Asian J. 2, 477–483. CSD CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spek, A. L. (2020). Acta Cryst. E76, 1–11. Web of Science CrossRef IUCr Journals Google Scholar
Travis, A. S. (2007). The Chemistry of Anilines, Part 1, edited by Z. Rappoport, pp. 1–73. Chichester: John Wiley and Sons. Google Scholar
Tsuchimoto, M., Nishimura, S. & Iwamura, H. (1973). Bull. Chem. Soc. Jpn, 46, 675–677. CrossRef CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zhang, Y., Awaga, K., Yoshikawa, H. & Xiong, R.-G. (2012). J. Mater. Chem. 22, 9841–9845. CSD CrossRef CAS Google Scholar

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research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Synthesis and crystal structures of N,2,4,6-tetra­methyl­anilinium tri­fluoro­methane­sulfonate and N-iso­propyl­­idene-N,2,4,6-tetra­methyl­anilinium tri­fluoro­methane­sulfonate

1. Chemical context

2. Structural commentary

3. Supra­molecular features

4. Database survey

5. Synthesis and crystallization

6. Refinement

Supporting information

Acknowledgements

Funding information

References

research communications

Synthesis and crystal structures of N,2,4,6-tetramethylanilinium trifluoromethanesulfonate and N-isopropylidene-N,2,4,6-tetramethylanilinium trifluoromethanesulfonate

3. Supramolecular features