Two ammonium tetra­chlorido­aluminate salts: how a twinned ortho­rhom­bic structure emulates a trigonal crystal system

We have determined the crystal structures of two tetra­chlorido­aluminate salts. Tetra­butyl­ammonium tetra­chlorido­aluminate benzene hemisolvate, (C₁₆H₃₆N)[AlCl₄]·0.5C₆H₆, (I), crystallizes with discrete cations, anions and solvent mol­ecules. The benzene mol­ecule is located on a centre of inversion. The structure of the benzene-free polymorph has been determined previously. Tetra­ethyl­ammonium tetra­chlorido­aluminate, (C₈H₂₀N)[AlCl₄], (II), also crystallizes with discrete cations and anions, and forms crystals which appear trigonal but are actually ortho­rhom­bic. With the additional reflections of the second and third domains of this nonmerohedral twin, a trigonal lattice is emulated, although the correct crystal system is ortho­rhom­bic.

S1. Introduction

In the course of our investigations of low-coordinate triele compounds (Wiberg et al., 1998; Budanow et al., 2012), we prepared (^tBu₃Si)₂ECl from ECl₃ (E = Al, Ga) and tri-tert-butyl­silanide (supersilanide) Na[Si^tBu₃] (Lerner, 2005). When ECl₃ (E = Al, Ga) in pentane was treated with one or two molar equivalents of Na[Si^tBu₃] (Lerner, 2005), the reaction mixture underwent a colour change to bright yellow (Wiberg et al., 1998). It is worth mentioning that in both cases we isolated colourless crystals of (^tBu₃Si)₂ECl. Therefore, we suggested that in solution an equilibrium of (^tBu₃Si)₂ECl and ECl₃ (E = Al, Ga) with the related ion pairs [^tBu₃Si–E–Si^tBu₃][ECl₄] exists and the yellow colour proceeds from the cation [^tBu₃Si–E–Si^tBu₃]⁺. However, up to now we could not isolate the ion pairs [^tBu₃Si–E–Si^tBu₃][ECl₄]. Very recently, we synthesized the two-coordinate cations [^tBu₃Si–E–Si^tBu₃][Al{OC(CF₃)₃}₄] (E = Al, Ga) (Budanow et al., 2012; Budanow, 2014). As a consequence thereof, the synthesis of [^tBu₃Si–E–Si^tBu₃][ECl₄] (E = Al, Ga) is now possible by the reaction of [^tBu₃Si–E–Si^tBu₃][Al{OC(CF₃)₃}₄] with [nBu₄N][ECl₄]. For this approach we synthesized [nBu₄N][AlCl₄] as a starting material. Apart from the benzene-free pseudopolymorph of (I), there is no structure in the Cambridge Crystallographic Database (Groom & Allen, 2014) containing the AlCl₄ anion and an ammonium cation with the N atom bonded to four C atoms.

S2. Experimental

S2.1. Synthesis and crystallization

All experiments were carried out using standard Schlenk techniques. The ammonium salts were obtained from commercial sources and used as purchased. AlCl₃ was prepared from Al and HCl gas. C₆H₆ was dried over Na and CH₂Cl₂ was dried over CaH₂. The solvents were freshly distilled prior to use.

Compound (I) was crystallized from a 1:1 mixture of Bu₄NCl and AlCl₃ in C₆H₆. The mixture was stirred for 1 h and filtered through a paper filter. The crystals grew on the paper at the upper rim of the filter. Crystals of (II) grew when the solvent of a clear and colourless solution of Et₄NCl and AlCl₃ (1:1) in CH₂Cl₂ was evaporated slowly.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms were refined using a riding model, with aromatic C—H = 0.95 Å, methyl C—H = 0.98 Å and methyl­ene C—H = 0.99 Å, and with U_iso(H) = 1.5U_eq(C) for methyl H atoms or 1.2U_eq(C) otherwise.

Compound (II) is a nonmerohedral twin. The initial cell determination gave a trigonal cell (a = b = 16.242 Å, c = 12.902 Å, α = β = 90°, γ = 120°). However, since the R_int value (0.399) for merging the data in this setting was rather high, the data were transformed to an orthorhombic C-centred lattice with a = 16.242 Å, b = 28.131 Å and c = 12.902 Å, and α = β = γ = 90°, leading to an acceptable R_int value of 0.060. However, the space group extinctions (h0l for h=2n weak and h0l for h + l=2n weak) did not match any space group. A thorough inspection of the reflection data revealed that all reflections with an odd sum of h + k were significantly weaker [mean I/σ(I) = 4.2] than the remaining [mean I/σ(I) = 22.2] reflections. Thus, the cell was transformed by (0.5 0.5 0/0 0 1/-0.5 0.5 0) to an orthorhombic primitive one with a = 8.119 Å, b = 12.902 Å and c = 14.063 Å, and α = β = γ = 90°. Now the systematic absence exceptions pointed to the space group Pc2₁b which is just another setting of Pca2₁ (transformation matrix: 001/100/010). In this space group, the structure could be solved, but refinement did not proceed satisfactorily (wR2 = 0.374, R1 = 0.121 for all data; one nonpositive definite atom). As a result, it became obvious that the structure was twinned. A test for twinning with the TWINROTMAT option in PLATON (Spek, 2009) gave two twin laws, i.e. (0.503 1.491 0.000/0.501 -0.503 0.000/0.000 0.000 -1.000) and (-0.497 1.497 0.000/0.503 0.497 0.000/0.000 0.000 -1.000).

For the refinement, the reflection data have to be read in via the HKLF 5 option in SHELXL (Sheldrick, 2008) and two additional parameters, called BASF, describing the fractional contribution of the twin domains had to be introduced. With these modifications, the structure can be satisfactorily refined (Table 1). The fractional contributions of the two minor twin domains refined to 0.1622 (16) and 0.1636 (19).

S3. Results and discussion

Tetra­butyl­ammonium tetra­chloridoaluminate benzene hemisolvate, (I) crystallizes with discrete cations and anions and solvent molecules (Fig. 1). The benzene molecule is located on a centre of inversion. The four Al—Cl distances do not vary markedly [2.1195 (10)–2.1389 (11) Å; Table 2] and the six bond angles at Al are close to ideal tetra­hedral values [108.12 (5)–111.33 (5)°] (Table 2). All four butyl chains of the cation display an all-trans conformation. The packing diagram (Fig. 2) shows that the three entities are located in layers parallel to the bc plane. There are two Al···N distances below 6 Å [N1···Al1 = 5.5296 (18) Å and N1···Al1ⁱ = 5.5764 (18) Å; symmetry code: (i) -x+1/2, y+1/2, -z+1/2] and five N···Cl contacts below 5 Å [N1···Cl3ⁱⁱ = 4.4060 (18) Å, N1···Cl1 = 4.4814 (18) Å, N1···Cl2ⁱ = 4.7479 (18) Å, N1···Cl4ⁱ = 4.753 (2) Å and N1···Cl2 = 4.8726 (18) Å; symmetry codes: (i) -x+1/2, y+1/2, -z+1/2; (ii) x+1, y, z]. The shortest Al···Al and N···N distances are listed in Table 3.

The structure of the benzene-free pseudo-polymorph of (I) has already been determined (Kanazawa et al., 2012), hereafter (Ia). It crystallizes with two half ions in the asymmetric unit, both of which are located on a twofold rotation axis parallel to [100]. The crystal packing (Fig. 3) shows that every cation is surrounded by six anions and vice versa. As a result, cations and anions are perfectly shielded from each other. There are two Al···N distances below 6 Å (5.766 Å) and four N···Cl contacts below 5 Å (4.471–4.523 Å). The shortest Al···Al and N···N distances are in the same range as for (I).

It is noteworthy, that tetra-n-butyl­ammonium tetra­bromidoaluminate (Rudawska-Frąckiewicz & Siekierski, 2004) is isomorphous (orthorhombic space group Pnna) with (Ia), whereas tetra-n-butyl­ammonium tetra­iodidoaluminate (Rogers et al., 1984) crystallizes in a different crystal system, i.e. monoclinic P2₁/n.

The crystal packing patterns of (I) and (Ia) resemble each other. The only difference is that in (I) additional solvent molecules are included in the crystal. Comparing the selected short distances in Table 3, there is only a difference for the N···N distances; the N···Al, N···Cl and Al···Al distances are in the same range.

Tetra­ethyl­ammonium tetra­chloridoaluminate, (II), also crystallizes with discrete cations and anions. The AlCl₄^2- anion is essentially tetra­hedral, with Al—Cl bond distances ranging from 2.1313 (14) Å for Al1—Cl3 to 2.1383 (14) Å for Al1—Cl4 (Table 4). The bond angles at Al are almost equal [108.14 (6)–110.38 (6)°; Table 4]. The bond lengths and angles at atom N1 differ slightly more from ideal tetra­hedral values [1.503 (5)–1.524 (4) Å and 107.7 (3)–111.6 (3)°; Table 4]. The ions form layers in the ac plane.

There are five N···Al distances below 6 Å ranging from 5.537 (8) [symmetry code for Al1 (x, y-1, z)] to 5.832 (8) Å [symmetry code for Al1 (-x+1/2, y, z-1/2)] and 11 N···Cl distances below 5 Å ranging from 4.460 (9) (N1···Cl1) to 4.999 Å [N1···Cl1(x, -y+1, z-1/2)].

Due to the change of butyl chains to ethyl chains, the cations of (II) are smaller than in (I) and (Ia). As a result, the Al···Al and N···N distances become significantly shorter (Table 3). On the other hand, the shortest N···Al and N···Cl distances do not show marked differences.

Related literature

For related literature, see: Budanow (2014); Budanow et al. (2012); Groom & Allen (2014); Kanazawa et al. (2012); Lerner (2005); Rogers et al. (1984); Rudawska-Frąckiewicz & Siekierski (2004); Sheldrick (2008); Spek (2009); Wiberg et al. (1998).

Computing details

For both compounds, data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001). Program(s) used to solve structure: SHELXS97 (Sheldrick, 2008) for (I); SHELXS97(Sheldrick, 2008) for (II). For both compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. Perspective view of (I), with displacement ellipsoids drawn at the 50% probability level. Atoms with suffix `A' were generated using the symmetry operator (-x, -y+2, -z).
	Fig. 2. Packing diagram of (I), viewed in the ac plane. H atoms have been omitted for clarity. [Please provide a version with a white background]
	Fig. 3. Packing diagram of solvent-free tetrabutylammonium tetrachloridoaluminate. H atoms have been omitted for clarity. [Please provide a version with a white background]
	Fig. 4. Perspective view of (II), with displacement ellipsoids drawn at the 50% probability level.
	Fig. 5. Packing diagram of (II), viewed in the bc plane. H atoms have been omitted for clarity.

(I) Tetrabutylammonium tetrachloridoaluminate benzene hemisolvate

Crystal data

(C16H36N)[AlCl4]·0.5C6H6	F(000) = 964
Mr = 450.29	Dx = 1.154 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 10.6887 (5) Å	Cell parameters from 29120 reflections
b = 13.8505 (5) Å	θ = 1.9–26.7°
c = 17.5554 (10) Å	µ = 0.49 mm^−1
β = 93.926 (4)°	T = 173 K
V = 2592.9 (2) Å^3	Block, colourless
Z = 4	0.40 × 0.30 × 0.30 mm

Data collection

Stoe IPDS II two-circle diffractometer	4643 reflections with I > 2σ(I)
Radiation source: Genix 3D IµS microfocus X-ray source	Rint = 0.072
ω scans	θmax = 26.2°, θmin = 2.3°
Absorption correction: multi-scan (X-AREA; Stoe & Cie, 2001)	h = −13→13
Tmin = 0.781, Tmax = 0.844	k = −16→17
20778 measured reflections	l = −21→21
5137 independent reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.058	H-atom parameters constrained
wR(F^2) = 0.162	w = 1/[σ^2(Fo^2) + (0.0825P)^2 + 1.8021P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max = 0.001
5137 reflections	Δρmax = 1.15 e Å^−3
226 parameters	Δρmin = −0.66 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

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

	x	y	z	Uiso*/Ueq
Al1	0.04187 (7)	0.64919 (5)	0.23509 (4)	0.0440 (2)
Cl1	0.14201 (7)	0.77756 (5)	0.21111 (4)	0.0557 (2)
Cl2	0.17312 (6)	0.54100 (5)	0.27113 (5)	0.0612 (2)
Cl3	−0.07795 (8)	0.67600 (6)	0.32452 (6)	0.0748 (3)
Cl4	−0.06447 (10)	0.59758 (8)	0.13572 (6)	0.0954 (4)
N1	0.52474 (15)	0.75811 (12)	0.33139 (10)	0.0306 (4)
C1	0.6011 (2)	0.81451 (15)	0.27622 (12)	0.0337 (4)
H1A	0.6239	0.8776	0.2997	0.040*
H1B	0.6800	0.7789	0.2698	0.040*
C2	0.5368 (2)	0.83264 (17)	0.19788 (13)	0.0412 (5)
H2A	0.5244	0.7706	0.1704	0.049*
H2B	0.4534	0.8620	0.2033	0.049*
C3	0.6156 (3)	0.8996 (2)	0.15254 (14)	0.0504 (6)
H3A	0.6954	0.8671	0.1428	0.061*
H3B	0.6360	0.9583	0.1831	0.061*
C4	0.5489 (3)	0.9287 (3)	0.07683 (16)	0.0649 (8)
H4A	0.6030	0.9719	0.0495	0.097*
H4B	0.4706	0.9621	0.0862	0.097*
H4C	0.5301	0.8709	0.0460	0.097*
C5	0.47169 (19)	0.66614 (14)	0.29444 (13)	0.0345 (4)
H5A	0.4280	0.6295	0.3331	0.041*
H5B	0.4083	0.6842	0.2531	0.041*
C6	0.5675 (2)	0.60024 (16)	0.26130 (16)	0.0438 (5)
H6A	0.6155	0.6369	0.2247	0.053*
H6B	0.6272	0.5767	0.3028	0.053*
C7	0.5038 (2)	0.51476 (16)	0.22092 (14)	0.0415 (5)
H7A	0.4625	0.4751	0.2588	0.050*
H7B	0.4379	0.5388	0.1833	0.050*
C8	0.5933 (3)	0.4524 (2)	0.1806 (2)	0.0659 (8)
H8A	0.5474	0.3983	0.1559	0.099*
H8B	0.6580	0.4274	0.2176	0.099*
H8C	0.6327	0.4907	0.1419	0.099*
C9	0.41782 (19)	0.82216 (15)	0.35351 (13)	0.0354 (4)
H9A	0.3642	0.8369	0.3067	0.042*
H9B	0.4539	0.8840	0.3729	0.042*
C10	0.3346 (2)	0.78246 (17)	0.41280 (14)	0.0408 (5)
H10A	0.3866	0.7620	0.4588	0.049*
H10B	0.2878	0.7255	0.3920	0.049*
C11	0.2432 (3)	0.8606 (2)	0.43385 (17)	0.0541 (6)
H11A	0.2911	0.9159	0.4566	0.065*
H11B	0.1961	0.8837	0.3869	0.065*
C12	0.1513 (3)	0.8257 (3)	0.4897 (2)	0.0723 (9)
H12A	0.0949	0.8787	0.5014	0.109*
H12B	0.1973	0.8039	0.5367	0.109*
H12C	0.1020	0.7720	0.4669	0.109*
C13	0.61026 (19)	0.73041 (15)	0.40056 (12)	0.0337 (4)
H13A	0.5636	0.6866	0.4330	0.040*
H13B	0.6822	0.6937	0.3828	0.040*
C14	0.6609 (2)	0.81388 (17)	0.44949 (13)	0.0396 (5)
H14A	0.6981	0.8629	0.4168	0.048*
H14B	0.5916	0.8446	0.4752	0.048*
C15	0.7598 (3)	0.7778 (2)	0.50888 (14)	0.0508 (6)
H15A	0.7218	0.7289	0.5414	0.061*
H15B	0.8279	0.7461	0.4828	0.061*
C16	0.8147 (3)	0.8585 (2)	0.55898 (16)	0.0570 (7)
H16A	0.8784	0.8320	0.5961	0.085*
H16B	0.7480	0.8890	0.5861	0.085*
H16C	0.8534	0.9067	0.5271	0.085*
C21	−0.0328 (4)	0.9353 (2)	0.05424 (18)	0.0691 (9)
H21	−0.0565	0.8904	0.0915	0.083*
C22	−0.1185 (3)	0.9645 (2)	−0.0030 (2)	0.0713 (9)
H22	−0.2015	0.9396	−0.0051	0.086*
C23	−0.0848 (4)	1.0298 (2)	−0.05744 (18)	0.0659 (8)
H23	−0.1444	1.0499	−0.0969	0.079*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Al1	0.0351 (4)	0.0420 (4)	0.0545 (4)	−0.0019 (3)	0.0003 (3)	−0.0010 (3)
Cl1	0.0558 (4)	0.0428 (3)	0.0686 (4)	−0.0031 (3)	0.0066 (3)	0.0098 (3)
Cl2	0.0422 (3)	0.0436 (4)	0.0982 (6)	0.0037 (3)	0.0086 (3)	0.0057 (3)
Cl3	0.0619 (5)	0.0603 (5)	0.1069 (7)	0.0075 (3)	0.0408 (4)	−0.0004 (4)
Cl4	0.0945 (7)	0.1003 (7)	0.0853 (6)	−0.0225 (6)	−0.0387 (5)	−0.0065 (5)
N1	0.0276 (8)	0.0271 (8)	0.0367 (9)	−0.0008 (6)	0.0003 (6)	0.0025 (7)
C1	0.0328 (10)	0.0321 (10)	0.0360 (10)	−0.0044 (8)	0.0003 (8)	0.0061 (8)
C2	0.0447 (12)	0.0425 (12)	0.0357 (11)	−0.0014 (10)	−0.0023 (9)	0.0032 (9)
C3	0.0538 (14)	0.0565 (15)	0.0411 (12)	0.0021 (12)	0.0040 (11)	0.0157 (11)
C4	0.077 (2)	0.077 (2)	0.0408 (13)	0.0145 (16)	0.0046 (13)	0.0165 (13)
C5	0.0305 (10)	0.0277 (10)	0.0449 (11)	−0.0034 (8)	−0.0002 (8)	0.0002 (8)
C6	0.0326 (11)	0.0345 (11)	0.0640 (15)	0.0007 (9)	0.0021 (10)	−0.0071 (10)
C7	0.0397 (11)	0.0339 (11)	0.0504 (13)	0.0017 (9)	−0.0013 (9)	−0.0033 (9)
C8	0.0523 (15)	0.0499 (16)	0.096 (2)	0.0045 (13)	0.0076 (15)	−0.0250 (15)
C9	0.0306 (10)	0.0299 (10)	0.0454 (11)	0.0034 (8)	0.0011 (8)	0.0045 (8)
C10	0.0351 (11)	0.0385 (11)	0.0494 (13)	0.0016 (9)	0.0074 (9)	0.0039 (9)
C11	0.0426 (13)	0.0542 (15)	0.0669 (16)	0.0105 (11)	0.0146 (12)	0.0021 (13)
C12	0.0513 (16)	0.089 (2)	0.080 (2)	0.0063 (16)	0.0264 (15)	−0.0020 (18)
C13	0.0312 (10)	0.0336 (10)	0.0359 (10)	0.0028 (8)	0.0002 (8)	0.0067 (8)
C14	0.0401 (11)	0.0393 (11)	0.0389 (11)	−0.0018 (9)	−0.0017 (9)	0.0022 (9)
C15	0.0565 (15)	0.0523 (14)	0.0417 (12)	0.0092 (12)	−0.0095 (11)	−0.0022 (11)
C16	0.0571 (16)	0.0672 (17)	0.0447 (13)	0.0022 (13)	−0.0107 (11)	−0.0068 (12)
C21	0.106 (3)	0.0486 (15)	0.0554 (16)	0.0004 (17)	0.0273 (17)	−0.0043 (13)
C22	0.0611 (18)	0.0637 (19)	0.091 (2)	−0.0059 (15)	0.0170 (17)	−0.0332 (18)
C23	0.084 (2)	0.0569 (17)	0.0552 (16)	0.0186 (16)	−0.0095 (15)	−0.0169 (13)

Geometric parameters (Å, º)

Al1—Cl2	2.1195 (10)	C9—C10	1.518 (3)
Al1—Cl3	2.1257 (11)	C9—H9A	0.9900
Al1—Cl1	2.1321 (10)	C9—H9B	0.9900
Al1—Cl4	2.1389 (11)	C10—C11	1.520 (3)
N1—C9	1.518 (3)	C10—H10A	0.9900
N1—C13	1.518 (3)	C10—H10B	0.9900
N1—C5	1.521 (3)	C11—C12	1.514 (4)
N1—C1	1.524 (3)	C11—H11A	0.9900
C1—C2	1.516 (3)	C11—H11B	0.9900
C1—H1A	0.9900	C12—H12A	0.9800
C1—H1B	0.9900	C12—H12B	0.9800
C2—C3	1.515 (3)	C12—H12C	0.9800
C2—H2A	0.9900	C13—C14	1.518 (3)
C2—H2B	0.9900	C13—H13A	0.9900
C3—C4	1.519 (4)	C13—H13B	0.9900
C3—H3A	0.9900	C14—C15	1.517 (3)
C3—H3B	0.9900	C14—H14A	0.9900
C4—H4A	0.9800	C14—H14B	0.9900
C4—H4B	0.9800	C15—C16	1.516 (4)
C4—H4C	0.9800	C15—H15A	0.9900
C5—C6	1.517 (3)	C15—H15B	0.9900
C5—H5A	0.9900	C16—H16A	0.9800
C5—H5B	0.9900	C16—H16B	0.9800
C6—C7	1.517 (3)	C16—H16C	0.9800
C6—H6A	0.9900	C21—C23^i	1.344 (5)
C6—H6B	0.9900	C21—C22	1.373 (5)
C7—C8	1.502 (4)	C21—H21	0.9500
C7—H7A	0.9900	C22—C23	1.382 (5)
C7—H7B	0.9900	C22—H22	0.9500
C8—H8A	0.9800	C23—C21^i	1.344 (5)
C8—H8B	0.9800	C23—H23	0.9500
C8—H8C	0.9800
Cl2—Al1—Cl3	108.84 (5)	H8B—C8—H8C	109.5
Cl2—Al1—Cl1	108.52 (4)	N1—C9—C10	116.78 (17)
Cl3—Al1—Cl1	109.64 (5)	N1—C9—H9A	108.1
Cl2—Al1—Cl4	108.12 (5)	C10—C9—H9A	108.1
Cl3—Al1—Cl4	110.33 (5)	N1—C9—H9B	108.1
Cl1—Al1—Cl4	111.33 (5)	C10—C9—H9B	108.1
C9—N1—C13	111.45 (16)	H9A—C9—H9B	107.3
C9—N1—C5	109.46 (15)	C9—C10—C11	108.97 (19)
C13—N1—C5	108.41 (15)	C9—C10—H10A	109.9
C9—N1—C1	107.96 (15)	C11—C10—H10A	109.9
C13—N1—C1	108.56 (15)	C9—C10—H10B	109.9
C5—N1—C1	111.01 (16)	C11—C10—H10B	109.9
C2—C1—N1	115.61 (17)	H10A—C10—H10B	108.3
C2—C1—H1A	108.4	C12—C11—C10	112.7 (2)
N1—C1—H1A	108.4	C12—C11—H11A	109.0
C2—C1—H1B	108.4	C10—C11—H11A	109.0
N1—C1—H1B	108.4	C12—C11—H11B	109.0
H1A—C1—H1B	107.4	C10—C11—H11B	109.0
C3—C2—C1	110.15 (19)	H11A—C11—H11B	107.8
C3—C2—H2A	109.6	C11—C12—H12A	109.5
C1—C2—H2A	109.6	C11—C12—H12B	109.5
C3—C2—H2B	109.6	H12A—C12—H12B	109.5
C1—C2—H2B	109.6	C11—C12—H12C	109.5
H2A—C2—H2B	108.1	H12A—C12—H12C	109.5
C2—C3—C4	112.2 (2)	H12B—C12—H12C	109.5
C2—C3—H3A	109.2	C14—C13—N1	115.60 (17)
C4—C3—H3A	109.2	C14—C13—H13A	108.4
C2—C3—H3B	109.2	N1—C13—H13A	108.4
C4—C3—H3B	109.2	C14—C13—H13B	108.4
H3A—C3—H3B	107.9	N1—C13—H13B	108.4
C3—C4—H4A	109.5	H13A—C13—H13B	107.4
C3—C4—H4B	109.5	C15—C14—C13	110.05 (19)
H4A—C4—H4B	109.5	C15—C14—H14A	109.7
C3—C4—H4C	109.5	C13—C14—H14A	109.7
H4A—C4—H4C	109.5	C15—C14—H14B	109.7
H4B—C4—H4C	109.5	C13—C14—H14B	109.7
C6—C5—N1	115.19 (17)	H14A—C14—H14B	108.2
C6—C5—H5A	108.5	C16—C15—C14	112.3 (2)
N1—C5—H5A	108.5	C16—C15—H15A	109.1
C6—C5—H5B	108.5	C14—C15—H15A	109.1
N1—C5—H5B	108.5	C16—C15—H15B	109.1
H5A—C5—H5B	107.5	C14—C15—H15B	109.1
C7—C6—C5	110.83 (18)	H15A—C15—H15B	107.9
C7—C6—H6A	109.5	C15—C16—H16A	109.5
C5—C6—H6A	109.5	C15—C16—H16B	109.5
C7—C6—H6B	109.5	H16A—C16—H16B	109.5
C5—C6—H6B	109.5	C15—C16—H16C	109.5
H6A—C6—H6B	108.1	H16A—C16—H16C	109.5
C8—C7—C6	112.9 (2)	H16B—C16—H16C	109.5
C8—C7—H7A	109.0	C23^i—C21—C22	120.0 (3)
C6—C7—H7A	109.0	C23^i—C21—H21	120.0
C8—C7—H7B	109.0	C22—C21—H21	120.0
C6—C7—H7B	109.0	C21—C22—C23	120.5 (3)
H7A—C7—H7B	107.8	C21—C22—H22	119.8
C7—C8—H8A	109.5	C23—C22—H22	119.8
C7—C8—H8B	109.5	C21^i—C23—C22	119.6 (3)
H8A—C8—H8B	109.5	C21^i—C23—H23	120.2
C7—C8—H8C	109.5	C22—C23—H23	120.2
H8A—C8—H8C	109.5
C9—N1—C1—C2	−69.5 (2)	C5—N1—C9—C10	63.2 (2)
C13—N1—C1—C2	169.55 (18)	C1—N1—C9—C10	−175.89 (18)
C5—N1—C1—C2	50.5 (2)	N1—C9—C10—C11	173.7 (2)
N1—C1—C2—C3	172.87 (19)	C9—C10—C11—C12	176.8 (2)
C1—C2—C3—C4	−173.9 (2)	C9—N1—C13—C14	−53.3 (2)
C9—N1—C5—C6	173.39 (19)	C5—N1—C13—C14	−173.80 (18)
C13—N1—C5—C6	−64.8 (2)	C1—N1—C13—C14	65.5 (2)
C1—N1—C5—C6	54.3 (2)	N1—C13—C14—C15	−171.30 (19)
N1—C5—C6—C7	−175.83 (18)	C13—C14—C15—C16	179.4 (2)
C5—C6—C7—C8	174.4 (2)	C23^i—C21—C22—C23	−0.1 (5)
C13—N1—C9—C10	−56.7 (2)	C21—C22—C23—C21^i	0.1 (5)

Symmetry code: (i) −x, −y+2, −z.

(II) Tetraethylammonium tetrachloridoaluminate

Crystal data

(C8H20N)[AlCl4]	Dx = 1.349 Mg m^−3
Mr = 299.03	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pca21	Cell parameters from 13398 reflections
a = 14.0348 (10) Å	θ = 3.2–26.4°
b = 8.1362 (7) Å	µ = 0.83 mm^−1
c = 12.8892 (12) Å	T = 173 K
V = 1471.8 (2) Å^3	Block, colourless
Z = 4	0.10 × 0.10 × 0.10 mm
F(000) = 624

Data collection

Stoe IPDS II two-circle- diffractometer	2423 reflections with I > 2σ(I)
Radiation source: Genix 3D IµS microfocus X-ray source	Rint = 0.028
ω scans	θmax = 25.8°, θmin = 4.0°
Absorption correction: multi-scan X-AREA (Stoe & Cie, 2001)	h = 0→15
Tmin = 0.897, Tmax = 0.904	k = −4→9
6472 measured reflections	l = −15→15
2522 independent reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.023	w = 1/[σ^2(Fo^2) + (0.0263P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.052	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 0.20 e Å^−3
2522 reflections	Δρmin = −0.15 e Å^−3
129 parameters	Absolute structure: Flack x determined using 1046 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
1 restraint	Absolute structure parameter: −0.04 (5)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refined as a 3-component twin.

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

	x	y	z	Uiso*/Ueq
Al1	0.24065 (8)	0.72153 (13)	0.52107 (7)	0.0232 (2)
Cl1	0.10146 (7)	0.69274 (11)	0.45644 (7)	0.0306 (2)
Cl2	0.23073 (8)	0.72358 (13)	0.68639 (6)	0.0335 (2)
Cl3	0.32847 (7)	0.52335 (10)	0.47060 (7)	0.0309 (2)
Cl4	0.30042 (7)	0.95065 (10)	0.47242 (7)	0.0334 (2)
N1	0.0859 (2)	0.2192 (4)	0.2809 (2)	0.0203 (6)
C1	0.0915 (3)	0.0357 (4)	0.2601 (3)	0.0253 (8)
H1A	0.1239	0.0186	0.1927	0.030*
H1B	0.1315	−0.0154	0.3145	0.030*
C2	−0.0035 (3)	−0.0524 (5)	0.2574 (3)	0.0315 (9)
H2A	0.0069	−0.1695	0.2435	0.047*
H2B	−0.0356	−0.0394	0.3244	0.047*
H2C	−0.0433	−0.0053	0.2024	0.047*
C3	0.1843 (3)	0.2859 (5)	0.2990 (3)	0.0262 (8)
H3A	0.2099	0.2359	0.3632	0.031*
H3B	0.1793	0.4057	0.3110	0.031*
C4	0.2555 (4)	0.2571 (5)	0.2122 (4)	0.0392 (10)
H4A	0.3171	0.3049	0.2314	0.059*
H4B	0.2630	0.1387	0.2007	0.059*
H4C	0.2323	0.3091	0.1484	0.059*
C5	0.0245 (3)	0.2566 (4)	0.3755 (3)	0.0253 (8)
H5A	0.0255	0.3767	0.3878	0.030*
H5B	−0.0421	0.2254	0.3596	0.030*
C6	0.0545 (3)	0.1703 (5)	0.4745 (3)	0.0353 (9)
H6A	0.0113	0.2014	0.5309	0.053*
H6B	0.0519	0.0511	0.4641	0.053*
H6C	0.1197	0.2028	0.4924	0.053*
C7	0.0390 (3)	0.2995 (4)	0.1872 (3)	0.0247 (8)
H7A	0.0794	0.2792	0.1255	0.030*
H7B	−0.0232	0.2453	0.1748	0.030*
C8	0.0225 (3)	0.4827 (5)	0.1968 (3)	0.0318 (9)
H8A	−0.0078	0.5237	0.1333	0.048*
H8B	−0.0191	0.5045	0.2563	0.048*
H8C	0.0837	0.5385	0.2069	0.048*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Al1	0.0224 (7)	0.0241 (5)	0.0232 (4)	−0.0009 (5)	0.0001 (4)	0.0001 (4)
Cl1	0.0257 (5)	0.0346 (4)	0.0316 (4)	−0.0019 (4)	−0.0057 (4)	−0.0010 (4)
Cl2	0.0347 (6)	0.0432 (6)	0.0227 (4)	−0.0013 (4)	0.0002 (4)	−0.0022 (4)
Cl3	0.0305 (5)	0.0293 (4)	0.0329 (4)	0.0041 (3)	0.0020 (5)	−0.0020 (4)
Cl4	0.0309 (5)	0.0267 (4)	0.0426 (5)	−0.0040 (3)	0.0023 (5)	0.0043 (4)
N1	0.0194 (18)	0.0185 (14)	0.0230 (13)	0.0018 (13)	−0.0014 (11)	−0.0014 (11)
C1	0.030 (2)	0.0179 (16)	0.0279 (16)	0.0030 (15)	−0.0003 (15)	−0.0033 (13)
C2	0.036 (3)	0.0228 (18)	0.035 (2)	−0.0044 (16)	−0.0038 (17)	−0.0036 (15)
C3	0.022 (2)	0.0243 (17)	0.0325 (19)	0.0016 (16)	−0.0056 (15)	−0.0012 (13)
C4	0.026 (3)	0.042 (2)	0.050 (3)	−0.003 (2)	0.0057 (16)	0.0025 (18)
C5	0.025 (3)	0.026 (2)	0.0249 (18)	0.0024 (14)	0.0027 (15)	−0.0054 (12)
C6	0.040 (3)	0.041 (2)	0.0251 (18)	0.0050 (17)	0.0029 (18)	−0.0042 (18)
C7	0.022 (2)	0.0283 (18)	0.0235 (15)	0.0045 (15)	−0.0027 (14)	0.0022 (15)
C8	0.033 (3)	0.023 (2)	0.0388 (19)	0.0018 (17)	−0.0032 (17)	0.0071 (16)

Geometric parameters (Å, º)

Al1—Cl3	2.1313 (14)	C3—H3B	0.9900
Al1—Cl2	2.1354 (11)	C4—H4A	0.9800
Al1—Cl1	2.1365 (14)	C4—H4B	0.9800
Al1—Cl4	2.1383 (14)	C4—H4C	0.9800
N1—C3	1.503 (5)	C5—C6	1.516 (5)
N1—C1	1.519 (4)	C5—H5A	0.9900
N1—C5	1.523 (4)	C5—H5B	0.9900
N1—C7	1.524 (4)	C6—H6A	0.9800
C1—C2	1.514 (5)	C6—H6B	0.9800
C1—H1A	0.9900	C6—H6C	0.9800
C1—H1B	0.9900	C7—C8	1.513 (5)
C2—H2A	0.9800	C7—H7A	0.9900
C2—H2B	0.9800	C7—H7B	0.9900
C2—H2C	0.9800	C8—H8A	0.9800
C3—C4	1.518 (6)	C8—H8B	0.9800
C3—H3A	0.9900	C8—H8C	0.9800
Cl3—Al1—Cl2	110.38 (6)	C3—C4—H4A	109.5
Cl3—Al1—Cl1	109.08 (6)	C3—C4—H4B	109.5
Cl2—Al1—Cl1	109.29 (7)	H4A—C4—H4B	109.5
Cl3—Al1—Cl4	110.07 (6)	C3—C4—H4C	109.5
Cl2—Al1—Cl4	108.14 (6)	H4A—C4—H4C	109.5
Cl1—Al1—Cl4	109.87 (6)	H4B—C4—H4C	109.5
C3—N1—C1	109.5 (3)	C6—C5—N1	115.0 (3)
C3—N1—C5	108.9 (3)	C6—C5—H5A	108.5
C1—N1—C5	111.6 (3)	N1—C5—H5A	108.5
C3—N1—C7	111.4 (3)	C6—C5—H5B	108.5
C1—N1—C7	107.7 (3)	N1—C5—H5B	108.5
C5—N1—C7	107.7 (3)	H5A—C5—H5B	107.5
C2—C1—N1	115.1 (3)	C5—C6—H6A	109.5
C2—C1—H1A	108.5	C5—C6—H6B	109.5
N1—C1—H1A	108.5	H6A—C6—H6B	109.5
C2—C1—H1B	108.5	C5—C6—H6C	109.5
N1—C1—H1B	108.5	H6A—C6—H6C	109.5
H1A—C1—H1B	107.5	H6B—C6—H6C	109.5
C1—C2—H2A	109.5	C8—C7—N1	115.1 (3)
C1—C2—H2B	109.5	C8—C7—H7A	108.5
H2A—C2—H2B	109.5	N1—C7—H7A	108.5
C1—C2—H2C	109.5	C8—C7—H7B	108.5
H2A—C2—H2C	109.5	N1—C7—H7B	108.5
H2B—C2—H2C	109.5	H7A—C7—H7B	107.5
N1—C3—C4	115.8 (3)	C7—C8—H8A	109.5
N1—C3—H3A	108.3	C7—C8—H8B	109.5
C4—C3—H3A	108.3	H8A—C8—H8B	109.5
N1—C3—H3B	108.3	C7—C8—H8C	109.5
C4—C3—H3B	108.3	H8A—C8—H8C	109.5
H3A—C3—H3B	107.4	H8B—C8—H8C	109.5
C3—N1—C1—C2	170.8 (3)	C3—N1—C5—C6	−65.5 (4)
C5—N1—C1—C2	50.1 (4)	C1—N1—C5—C6	55.6 (4)
C7—N1—C1—C2	−67.9 (4)	C7—N1—C5—C6	173.6 (3)
C1—N1—C3—C4	57.0 (4)	C3—N1—C7—C8	−63.0 (4)
C5—N1—C3—C4	179.3 (3)	C1—N1—C7—C8	176.8 (3)
C7—N1—C3—C4	−62.0 (4)	C5—N1—C7—C8	56.4 (4)