Carbon-atom hybridization tunes the halogen-bond strength in the series of DABCO·C₂H_2nI₂ (n = 0–2) cocrystals

Two new cocrystals of 1,4-di­aza­bicyclo­[2.2.2]octane (DABCO, C₆H₁₂N₂) with 1,2-di­iodo­ethene (1,2-C₂H₂I₂) and 1,2-di­iodo­ethane (1,2-C₂H₄I₂) com­plete a series of halogen-bond-assisted cocrystals which started with DABCO·C₂I₂ [Perkins et al. (2012). CrystEngComm, 14, 3033–3038]. The structural and com­­putational analysis of this series illustrate the correlation between the polarization of the I atom and the hybridization of the C atom bound to it. The formation of a rather stable halogen bond by the alkylic iodide of saturated 1,2-C₂H₄I₂ was unusual and respective cocrystals are formed only in nonpolar solvents, while, in the polar medium of aceto­nitrile, a very intense reaction of DABCO quaternization takes place resulting in 1-(2-iodo­eth­yl)-4-aza-1-azonia­bi­cyclo­[2.2.2]octane triiodide, C₈H₁₆IN₂⁺·I₃⁻ or [N(CH₂CH₂)₃N–CH₂CH₂I][I₃].

Computing details

For all structures, data collection: APEX2 (Bruker, 2019); cell refinement: SAINT (Bruker, 2019); data reduction: SAINT (Bruker, 2019); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

1,2-Diiodoethene–1,4-diazabicyclo[2.2.2]octane (1/1) (2_dabco_c2h2i2)

Crystal data

C2H2I2·C6H12N2	F(000) = 728
Mr = 392.01	Dx = 2.306 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 6.6793 (3) Å	Cell parameters from 9964 reflections
b = 17.5562 (8) Å	θ = 2.4–31.5°
c = 9.9538 (4) Å	µ = 5.53 mm^−1
β = 104.667 (1)°	T = 100 K
V = 1129.18 (9) Å^3	Needle, colourless
Z = 4	0.52 × 0.09 × 0.09 mm

Data collection

Bruker APEXII CCD diffractometer	3836 reflections with I > 2σ(I)
φ and ω scans	θmax = 31.5°, θmin = 2.3°
Absorption correction: multi-scan (TWINABS; Bruker, 2012)	h = −9→9
Tmin = 0.451, Tmax = 0.746	k = 0→25
4065 measured reflections	l = 0→14
4065 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) + (0.0204P)^2 + 2.7249P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.053	(Δ/σ)max = 0.001
S = 1.11	Δρmax = 0.74 e Å^−3
4065 reflections	Δρmin = −1.23 e Å^−3
111 parameters	Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00034 (10)

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 2-component twin.

A Bruker SMART APEXII diffractometer equipped with a graphite-monochromator and a Bruker D8 Venture diffractometer (Mo Kα radiation (λ = 0.71070 Å) were used for the unit-cell determination and intensity data collection for crystals of 2–4. The data were collected by standard φ–ω scan techniques, and were reduced using SAINT (Bruker, 2015). SADABS (Bruker, 2016) software was used for scaling and absorption correction. The structures were solved by direct methods and refined by full-matrix least-squares against F² using OLEX2 (Dolomanov et al., 2009) and SHELXTL (Sheldrick, 2015). Non-H atoms were refined with anisotropic displacement parameters.

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

	x	y	z	Uiso*/Ueq
I1	0.70722 (3)	0.35891 (2)	0.54602 (2)	0.01490 (5)
I2	0.29561 (3)	0.39275 (2)	0.90357 (2)	0.01379 (5)
C1	0.5565 (5)	0.34924 (18)	0.7083 (3)	0.0176 (5)
H1	0.578361	0.304524	0.763844	0.021*
C2	0.4337 (4)	0.40248 (18)	0.7356 (3)	0.0151 (5)
H2	0.406521	0.446443	0.678251	0.018*
N1	0.9242 (4)	0.37058 (13)	0.3322 (3)	0.0140 (4)
N2	1.1105 (4)	0.37835 (13)	0.1361 (3)	0.0141 (4)
C3	0.7718 (4)	0.37389 (17)	0.1968 (3)	0.0158 (5)
H3A	0.681673	0.418973	0.193631	0.019*
H3B	0.683475	0.327825	0.184313	0.019*
C4	0.8830 (4)	0.37886 (18)	0.0779 (3)	0.0166 (5)
H4A	0.841829	0.335084	0.014204	0.020*
H4B	0.841296	0.426238	0.024170	0.020*
C5	1.0555 (5)	0.43948 (17)	0.3488 (3)	0.0169 (5)
H5A	1.158865	0.437933	0.439730	0.020*
H5B	0.968710	0.485401	0.346564	0.020*
C6	1.1679 (5)	0.44383 (17)	0.2305 (3)	0.0181 (5)
H6A	1.129729	0.491751	0.177811	0.022*
H6B	1.319450	0.444029	0.270728	0.022*
C7	1.0582 (5)	0.30327 (17)	0.3359 (3)	0.0170 (5)
H7A	0.973728	0.256323	0.326562	0.020*
H7B	1.163191	0.301288	0.426068	0.020*
C8	1.1679 (5)	0.30745 (17)	0.2158 (3)	0.0166 (5)
H8A	1.319709	0.305743	0.254433	0.020*
H8B	1.127132	0.263041	0.153573	0.020*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.01604 (8)	0.01710 (9)	0.01331 (8)	0.00030 (6)	0.00698 (6)	−0.00011 (7)
I2	0.01403 (8)	0.01533 (8)	0.01339 (8)	0.00006 (6)	0.00601 (6)	−0.00014 (7)
C1	0.0193 (12)	0.0197 (13)	0.0158 (12)	0.0008 (10)	0.0084 (10)	0.0023 (11)
C2	0.0155 (11)	0.0194 (12)	0.0124 (12)	0.0004 (10)	0.0071 (9)	0.0031 (10)
N1	0.0156 (10)	0.0157 (10)	0.0122 (10)	0.0015 (8)	0.0063 (8)	0.0004 (8)
N2	0.0147 (10)	0.0174 (11)	0.0119 (10)	0.0016 (8)	0.0063 (8)	−0.0004 (8)
C3	0.0126 (11)	0.0201 (12)	0.0149 (12)	−0.0004 (9)	0.0042 (10)	0.0005 (10)
C4	0.0161 (12)	0.0221 (13)	0.0118 (12)	0.0015 (10)	0.0037 (10)	0.0015 (10)
C5	0.0201 (13)	0.0166 (12)	0.0154 (13)	−0.0011 (10)	0.0066 (10)	−0.0038 (11)
C6	0.0186 (13)	0.0172 (12)	0.0198 (14)	−0.0029 (10)	0.0074 (11)	0.0008 (11)
C7	0.0204 (13)	0.0168 (12)	0.0153 (13)	0.0031 (10)	0.0070 (10)	0.0048 (11)
C8	0.0185 (12)	0.0172 (12)	0.0166 (13)	0.0030 (10)	0.0092 (10)	−0.0002 (11)

Geometric parameters (Å, º)

I1—C1	2.115 (3)	C3—C4	1.551 (4)
I2—C2	2.111 (3)	C4—H4A	0.9900
C1—H1	0.9500	C4—H4B	0.9900
C1—C2	1.317 (4)	C5—H5A	0.9900
C2—H2	0.9500	C5—H5B	0.9900
N1—C3	1.470 (4)	C5—C6	1.550 (4)
N1—C5	1.479 (4)	C6—H6A	0.9900
N1—C7	1.477 (4)	C6—H6B	0.9900
N2—C4	1.483 (4)	C7—H7A	0.9900
N2—C6	1.473 (4)	C7—H7B	0.9900
N2—C8	1.474 (4)	C7—C8	1.553 (4)
C3—H3A	0.9900	C8—H8A	0.9900
C3—H3B	0.9900	C8—H8B	0.9900
I1—C1—H1	118.6	N1—C5—H5A	109.7
C2—C1—I1	122.9 (2)	N1—C5—H5B	109.7
C2—C1—H1	118.6	N1—C5—C6	110.0 (2)
I2—C2—H2	119.1	H5A—C5—H5B	108.2
C1—C2—I2	121.8 (2)	C6—C5—H5A	109.7
C1—C2—H2	119.1	C6—C5—H5B	109.7
C3—N1—C5	108.9 (2)	N2—C6—C5	110.4 (2)
C3—N1—C7	109.2 (2)	N2—C6—H6A	109.6
C7—N1—C5	108.3 (2)	N2—C6—H6B	109.6
C6—N2—C4	108.6 (2)	C5—C6—H6A	109.6
C6—N2—C8	109.0 (2)	C5—C6—H6B	109.6
C8—N2—C4	108.4 (2)	H6A—C6—H6B	108.1
N1—C3—H3A	109.6	N1—C7—H7A	109.6
N1—C3—H3B	109.6	N1—C7—H7B	109.6
N1—C3—C4	110.3 (2)	N1—C7—C8	110.1 (2)
H3A—C3—H3B	108.1	H7A—C7—H7B	108.2
C4—C3—H3A	109.6	C8—C7—H7A	109.6
C4—C3—H3B	109.6	C8—C7—H7B	109.6
N2—C4—C3	110.1 (2)	N2—C8—C7	110.2 (2)
N2—C4—H4A	109.6	N2—C8—H8A	109.6
N2—C4—H4B	109.6	N2—C8—H8B	109.6
C3—C4—H4A	109.6	C7—C8—H8A	109.6
C3—C4—H4B	109.6	C7—C8—H8B	109.6
H4A—C4—H4B	108.2	H8A—C8—H8B	108.1
I1—C1—C2—I2	−177.47 (13)	C5—N1—C3—C4	58.9 (3)
N1—C3—C4—N2	0.3 (3)	C5—N1—C7—C8	−60.3 (3)
N1—C5—C6—N2	0.2 (3)	C6—N2—C4—C3	−59.2 (3)
N1—C7—C8—N2	1.6 (3)	C6—N2—C8—C7	58.1 (3)
C3—N1—C5—C6	−59.4 (3)	C7—N1—C3—C4	−59.1 (3)
C3—N1—C7—C8	58.1 (3)	C7—N1—C5—C6	59.3 (3)
C4—N2—C6—C5	58.8 (3)	C8—N2—C4—C3	59.1 (3)
C4—N2—C8—C7	−60.1 (3)	C8—N2—C6—C5	−59.2 (3)

1,2-Diiodoethane–1,4-diazabicyclo[2.2.2]octane (1/1) (3_dabco_c2h4i2)

Crystal data

C2H4I2·C6H12N2	Z = 2
Mr = 394.03	F(000) = 368
Triclinic, P1	Dx = 2.247 Mg m^−3
a = 6.3840 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.9645 (6) Å	Cell parameters from 9010 reflections
c = 10.5276 (7) Å	θ = 2.9–32.5°
α = 92.007 (1)°	µ = 5.36 mm^−1
β = 103.486 (1)°	T = 100 K
γ = 95.254 (1)°	Plate, colourless
V = 582.42 (7) Å^3	0.32 × 0.24 × 0.06 mm

Data collection

Bruker APEXII CCD diffractometer	2717 reflections with I > 2σ(I)
φ and ω scans	θmax = 29.0°, θmin = 2.0°
Absorption correction: multi-scan (TWINABS; Bruker, 2012)	h = −8→8
Tmin = 0.496, Tmax = 0.746	k = −12→12
3098 measured reflections	l = 0→14
3098 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)] = 0.021	H-atom parameters constrained
wR(F^2) = 0.040	w = 1/[σ^2(Fo^2) + (0.0072P)^2 + 0.8348P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max = 0.001
3098 reflections	Δρmax = 0.57 e Å^−3
110 parameters	Δρmin = −0.73 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.

Refinement. Refined as a 2-component twin.

A Bruker SMART APEXII diffractometer equipped with a graphite-monochromator and a Bruker D8 Venture diffractometer (Mo Kα radiation (λ = 0.71070 Å) were used for the unit-cell determination and intensity data collection for crystals of 2–4. The data were collected by standard φ–ω scan techniques, and were reduced using SAINT (Bruker, 2015). SADABS (Bruker, 2016) software was used for scaling and absorption correction. The structures were solved by direct methods and refined by full-matrix least-squares against F² using OLEX2 (Dolomanov et al., 2009) and SHELXTL (Sheldrick, 2015). Non-H atoms were refined with anisotropic displacement parameters.

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

	x	y	z	Uiso*/Ueq
I1	0.66942 (2)	0.22256 (2)	0.52953 (2)	0.01293 (5)
I2	0.26129 (2)	0.27742 (2)	0.88578 (2)	0.01309 (5)
C1	0.5424 (4)	0.1951 (3)	0.7033 (3)	0.0177 (5)
H1A	0.490300	0.088281	0.707388	0.021*
H1B	0.659599	0.224074	0.782409	0.021*
C2	0.3599 (4)	0.2898 (3)	0.7011 (3)	0.0150 (5)
H2A	0.235791	0.253650	0.627647	0.018*
H2B	0.407010	0.395210	0.687790	0.018*
N1	0.8810 (3)	0.2474 (2)	0.3114 (2)	0.0132 (4)
N2	1.0949 (3)	0.2596 (2)	0.1321 (2)	0.0143 (4)
C3	1.0083 (4)	0.1184 (3)	0.3145 (3)	0.0162 (5)
H3A	0.910404	0.024107	0.302845	0.019*
H3B	1.112083	0.119480	0.400736	0.019*
C4	1.1334 (4)	0.1237 (3)	0.2051 (3)	0.0160 (5)
H4A	1.290241	0.123534	0.244154	0.019*
H4B	1.085135	0.033514	0.144664	0.019*
C5	0.7328 (4)	0.2460 (3)	0.1810 (3)	0.0181 (5)
H5A	0.645103	0.331999	0.177422	0.022*
H5B	0.632902	0.152533	0.165149	0.022*
C6	0.8611 (4)	0.2560 (3)	0.0739 (3)	0.0178 (5)
H6A	0.813236	0.168348	0.010560	0.021*
H6B	0.831919	0.347908	0.026029	0.021*
C7	1.0311 (4)	0.3857 (3)	0.3306 (3)	0.0166 (5)
H7A	1.131156	0.389322	0.418279	0.020*
H7B	0.947950	0.474083	0.326330	0.020*
C8	1.1627 (4)	0.3916 (3)	0.2248 (3)	0.0172 (5)
H8A	1.140034	0.484216	0.177157	0.021*
H8B	1.318864	0.393925	0.266837	0.021*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.01249 (8)	0.01556 (8)	0.01126 (9)	0.00097 (6)	0.00403 (6)	0.00069 (6)
I2	0.01261 (8)	0.01584 (8)	0.01139 (9)	0.00152 (6)	0.00401 (6)	0.00030 (6)
C1	0.0187 (13)	0.0243 (14)	0.0138 (13)	0.0066 (11)	0.0088 (10)	0.0052 (11)
C2	0.0160 (12)	0.0171 (12)	0.0134 (13)	0.0025 (10)	0.0059 (10)	0.0036 (10)
N1	0.0119 (10)	0.0168 (10)	0.0114 (11)	0.0016 (8)	0.0037 (8)	0.0021 (8)
N2	0.0113 (10)	0.0192 (11)	0.0130 (11)	0.0027 (8)	0.0036 (8)	0.0022 (8)
C3	0.0186 (13)	0.0155 (12)	0.0155 (13)	0.0013 (10)	0.0060 (10)	0.0028 (10)
C4	0.0172 (12)	0.0137 (12)	0.0194 (14)	0.0055 (10)	0.0070 (10)	0.0030 (10)
C5	0.0111 (11)	0.0301 (15)	0.0131 (13)	0.0038 (10)	0.0021 (10)	0.0015 (11)
C6	0.0144 (12)	0.0278 (14)	0.0114 (13)	0.0026 (10)	0.0033 (10)	0.0018 (11)
C7	0.0220 (13)	0.0135 (11)	0.0147 (13)	0.0014 (10)	0.0056 (11)	−0.0005 (10)
C8	0.0163 (12)	0.0140 (12)	0.0219 (14)	−0.0008 (9)	0.0063 (11)	0.0021 (10)

Geometric parameters (Å, º)

I1—C1	2.179 (3)	C3—H3B	0.9900
I2—C2	2.183 (3)	C3—C4	1.547 (4)
C1—H1A	0.9900	C4—H4A	0.9900
C1—H1B	0.9900	C4—H4B	0.9900
C1—C2	1.500 (4)	C5—H5A	0.9900
C2—H2A	0.9900	C5—H5B	0.9900
C2—H2B	0.9900	C5—C6	1.541 (4)
N1—C3	1.470 (3)	C6—H6A	0.9900
N1—C5	1.473 (3)	C6—H6B	0.9900
N1—C7	1.473 (3)	C7—H7A	0.9900
N2—C4	1.473 (3)	C7—H7B	0.9900
N2—C6	1.472 (3)	C7—C8	1.543 (4)
N2—C8	1.473 (3)	C8—H8A	0.9900
C3—H3A	0.9900	C8—H8B	0.9900
I1—C1—H1A	109.5	C3—C4—H4A	109.6
I1—C1—H1B	109.5	C3—C4—H4B	109.6
H1A—C1—H1B	108.0	H4A—C4—H4B	108.1
C2—C1—I1	110.94 (18)	N1—C5—H5A	109.5
C2—C1—H1A	109.5	N1—C5—H5B	109.5
C2—C1—H1B	109.5	N1—C5—C6	110.6 (2)
I2—C2—H2A	109.7	H5A—C5—H5B	108.1
I2—C2—H2B	109.7	C6—C5—H5A	109.5
C1—C2—I2	109.62 (17)	C6—C5—H5B	109.5
C1—C2—H2A	109.7	N2—C6—C5	110.5 (2)
C1—C2—H2B	109.7	N2—C6—H6A	109.5
H2A—C2—H2B	108.2	N2—C6—H6B	109.5
C3—N1—C5	108.5 (2)	C5—C6—H6A	109.5
C3—N1—C7	108.3 (2)	C5—C6—H6B	109.5
C7—N1—C5	108.2 (2)	H6A—C6—H6B	108.1
C6—N2—C4	108.5 (2)	N1—C7—H7A	109.5
C6—N2—C8	108.6 (2)	N1—C7—H7B	109.5
C8—N2—C4	108.4 (2)	N1—C7—C8	110.7 (2)
N1—C3—H3A	109.5	H7A—C7—H7B	108.1
N1—C3—H3B	109.5	C8—C7—H7A	109.5
N1—C3—C4	110.7 (2)	C8—C7—H7B	109.5
H3A—C3—H3B	108.1	N2—C8—C7	110.3 (2)
C4—C3—H3A	109.5	N2—C8—H8A	109.6
C4—C3—H3B	109.5	N2—C8—H8B	109.6
N2—C4—C3	110.2 (2)	C7—C8—H8A	109.6
N2—C4—H4A	109.6	C7—C8—H8B	109.6
N2—C4—H4B	109.6	H8A—C8—H8B	108.1
I1—C1—C2—I2	−173.94 (11)	C5—N1—C3—C4	57.4 (3)
N1—C3—C4—N2	2.0 (3)	C5—N1—C7—C8	−59.8 (3)
N1—C5—C6—N2	1.7 (3)	C6—N2—C4—C3	−59.9 (3)
N1—C7—C8—N2	2.0 (3)	C6—N2—C8—C7	57.6 (3)
C3—N1—C5—C6	−59.6 (3)	C7—N1—C3—C4	−59.9 (3)
C3—N1—C7—C8	57.6 (3)	C7—N1—C5—C6	57.7 (3)
C4—N2—C6—C5	57.9 (3)	C8—N2—C4—C3	57.8 (3)
C4—N2—C8—C7	−60.1 (3)	C8—N2—C6—C5	−59.7 (3)

1-(2-Iodoethyl)-4-aza-1-azoniabicyclo[2.2.2]octane triiodide (4_ich2ch2-dabco_i3)

Crystal data

C8H16IN2^+·I3^−	Dx = 2.859 Mg m^−3
Mr = 647.83	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmc21	Cell parameters from 9348 reflections
a = 7.9725 (3) Å	θ = 2.5–30.5°
b = 16.2887 (7) Å	µ = 8.26 mm^−1
c = 11.5886 (5) Å	T = 100 K
V = 1504.91 (11) Å^3	Prism, yellow
Z = 4	0.3 × 0.1 × 0.1 mm
F(000) = 1160

Data collection

Bruker APEXII CCD diffractometer	2394 reflections with I > 2σ(I)
φ and ω scans	Rint = 0.038
Absorption correction: multi-scan (SADABS; Bruker, 2016)	θmax = 30.5°, θmin = 2.5°
Tmin = 0.423, Tmax = 0.746	h = −11→11
12547 measured reflections	k = −23→23
2448 independent reflections	l = −16→16

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.016	w = 1/[σ^2(Fo^2) + (0.0049P)^2 + 0.3668P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.033	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 0.48 e Å^−3
2448 reflections	Δρmin = −0.90 e Å^−3
98 parameters	Absolute structure: Flack x determined using 1116 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
1 restraint	Absolute structure parameter: −0.02 (2)

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. A Bruker SMART APEXII diffractometer equipped with a graphite-monochromator and a Bruker D8 Venture diffractometer (Mo Kα radiation (λ = 0.71070 Å) were used for the unit-cell determination and intensity data collection for crystals of 2–4. The data were collected by standard φ–ω scan techniques, and were reduced using SAINT (Bruker, 2015). SADABS (Bruker, 2016) software was used for scaling and absorption correction. The structures were solved by direct methods and refined by full-matrix least-squares against F² using OLEX2 (Dolomanov et al., 2009) and SHELXTL (Sheldrick, 2015). Non-H atoms were refined with anisotropic displacement parameters.

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

	x	y	z	Uiso*/Ueq
I1	0.500000	0.22877 (2)	0.63277 (3)	0.01330 (7)
I3	0.500000	0.13869 (2)	0.10137 (3)	0.01538 (7)
I4	0.500000	0.04244 (2)	−0.11083 (3)	0.01852 (8)
I2	0.500000	0.24039 (2)	0.31053 (3)	0.01728 (8)
N2	0.500000	0.4858 (3)	1.1106 (4)	0.0128 (9)
C2	0.500000	0.3619 (3)	0.8043 (5)	0.0147 (10)
H2	0.602 (5)	0.384 (3)	0.760 (4)	0.018*
C7	0.6533 (4)	0.3830 (2)	0.9909 (3)	0.0127 (7)
H7A	0.745 (5)	0.394 (3)	0.943 (4)	0.015*
C3	0.500000	0.4962 (3)	0.8967 (6)	0.0161 (11)
H3	0.400 (5)	0.506 (3)	0.851 (4)	0.019*
N1	0.500000	0.4040 (3)	0.9204 (4)	0.0126 (9)
C4	0.500000	0.5419 (3)	1.0125 (5)	0.0166 (11)
C8	0.6496 (5)	0.4337 (2)	1.1030 (3)	0.0161 (7)
H8A	0.652103	0.396060	1.170039	0.019*
H8B	0.750999	0.468714	1.106616	0.019*
C1	0.500000	0.2683 (3)	0.8090 (5)	0.0145 (10)
H4	0.607 (5)	0.578 (3)	1.026 (4)	0.017*
H1	0.400 (5)	0.247 (3)	0.850 (4)	0.017*
H7B	0.646 (6)	0.327 (3)	1.010 (4)	0.025 (13)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.01618 (15)	0.01272 (15)	0.01101 (14)	0.000	0.000	−0.00385 (13)
I3	0.01358 (14)	0.01467 (15)	0.01790 (16)	0.000	0.000	0.00405 (12)
I4	0.01875 (17)	0.01674 (18)	0.02009 (17)	0.000	0.000	0.00048 (14)
I2	0.01749 (16)	0.01924 (17)	0.01510 (17)	0.000	0.000	0.00315 (14)
N2	0.019 (2)	0.0118 (19)	0.008 (2)	0.000	0.000	0.0020 (16)
C2	0.023 (3)	0.011 (2)	0.010 (2)	0.000	0.000	0.000 (2)
C7	0.0160 (16)	0.0108 (15)	0.0112 (17)	0.0034 (13)	−0.0028 (13)	−0.0007 (13)
C3	0.026 (3)	0.010 (2)	0.013 (3)	0.000	0.000	0.001 (2)
N1	0.018 (2)	0.012 (2)	0.0075 (19)	0.000	0.000	−0.0014 (17)
C4	0.028 (3)	0.010 (2)	0.012 (2)	0.000	0.000	−0.0025 (19)
C8	0.0199 (18)	0.0164 (17)	0.0120 (16)	−0.0009 (13)	−0.0034 (13)	−0.0024 (14)
C1	0.018 (2)	0.016 (2)	0.009 (2)	0.000	0.000	−0.001 (2)

Geometric parameters (Å, º)

I1—C1	2.141 (6)	C7—C8	1.540 (5)
I3—I4	2.9164 (5)	C7—H7B	0.94 (5)
I3—I2	2.9359 (6)	C3—H3	0.97 (4)
N2—C4	1.457 (7)	C3—H3^i	0.97 (4)
N2—C8^i	1.466 (5)	C3—N1	1.526 (7)
N2—C8	1.466 (5)	C3—C4	1.535 (9)
C2—H2	1.03 (4)	C4—H4	1.05 (5)
C2—N1	1.510 (7)	C8—H8A	0.9900
C2—C1	1.524 (7)	C8—H8B	0.9900
C7—H7A	0.94 (5)	C1—H1^i	0.99 (4)
C7—N1	1.509 (4)	C1—H1	0.99 (4)
I4—I3—I2	178.171 (16)	C7^i—N1—C2	112.3 (3)
C4—N2—C8^i	108.4 (3)	C7—N1—C2	112.3 (3)
C4—N2—C8	108.4 (3)	C7—N1—C7^i	108.1 (4)
C8^i—N2—C8	108.8 (4)	C7^i—N1—C3	108.7 (3)
N1—C2—H2	106 (3)	C7—N1—C3	108.7 (3)
N1—C2—C1	115.0 (5)	N2—C4—C3	112.2 (4)
C1—C2—H2	112 (3)	N2—C4—H4	104 (2)
H7A—C7—H7B	112 (4)	C3—C4—H4	114 (2)
N1—C7—H7A	105 (3)	N2—C8—C7	112.1 (3)
N1—C7—C8	108.7 (3)	N2—C8—H8A	109.2
N1—C7—H7B	107 (3)	N2—C8—H8B	109.2
C8—C7—H7A	114 (3)	C7—C8—H8A	109.2
C8—C7—H7B	109 (3)	C7—C8—H8B	109.2
H3—C3—H3^i	111 (6)	H8A—C8—H8B	107.9
N1—C3—H3	105 (3)	I1—C1—H1	110 (3)
N1—C3—H3^i	105 (3)	I1—C1—H1^i	110 (3)
N1—C3—C4	108.6 (5)	C2—C1—I1	105.5 (4)
C4—C3—H3^i	113 (3)	C2—C1—H1^i	112 (3)
C4—C3—H3	113 (3)	C2—C1—H1	112 (3)
C2—N1—C3	106.6 (4)	H1—C1—H1^i	107 (6)
N1—C2—C1—I1	180.000 (1)	C8—N2—C4—C3	59.0 (3)
N1—C7—C8—N2	1.1 (4)	C8^i—N2—C8—C7	57.8 (5)
N1—C3—C4—N2	0.000 (2)	C8—C7—N1—C2	175.5 (3)
C4—N2—C8—C7	−59.9 (4)	C8—C7—N1—C7^i	−60.0 (5)
C4—C3—N1—C2	180.000 (2)	C8—C7—N1—C3	57.8 (4)
C4—C3—N1—C7	−58.7 (3)	C1—C2—N1—C7	61.0 (3)
C4—C3—N1—C7^i	58.7 (3)	C1—C2—N1—C7^i	−61.0 (3)
C8^i—N2—C4—C3	−59.0 (3)	C1—C2—N1—C3	180.000 (2)

Symmetry code: (i) −x+1, y, z.