Crystal structure of 4,4′-(disulfanedi­yl)dipyridinium chloride triiodide

4,4′-(Disulfanedi­yl)dipyridinium chloride triiodide, C₁₀H₁₀N₂S₂²⁺·Cl⁻·I₃⁻, (1) was synthesized by reaction of 4,4′-di­pyridyl­disulfide with ICl in a 1:1 molar ratio in di­chloro­methane solution. The structural characterization of 1 by SC-XRD analysis was supported by elemental analysis, FT–IR, and FT–Raman spectroscopic measurements.

1. Chemical context

The reactions of pnictogen/chalcogen donors with dihalogens X₂ or inter­halogens XY (X, Y = Cl, Br, I) afford a variety of products depending on the nature of the donor, the dihalogen/inter­halogen, and the reaction conditions (Aragoni et al., 2008; Rimmer et al., 1998; Aragoni et al., 2022; Knight et al., 2012). For chalcogen donors, charge–transfer (CT) ‘spoke’ adducts, hypercoordinate ‘T-shaped’ adducts, halonium adducts, and different types of cationic oxidation products of the donors have been identified and structurally characterized (Knight et al., 2012; Saab et al., 2022). Worthy of note, diiodine CT-adducts have been extensively investigated, also with a view to their application as leaching agents for toxic (Isaia et al., 2011) and precious metals (Zupanc et al., 2022) in waste from electrical and electronic equipment (WEEE). Among the pnictogen donors, many studies have focused on (poly)pyridyl derivatives. Analogous to S/Se-donors, the reactions of pyridyl donors with X₂/XY have resulted in the formation of CT-adducts featuring a linear N⋯X—Y group (Kukkonen et al., 2019; Tuikka & Haukka, 2015) and halonium derivatives with an N⋯X⁺⋯N moiety (X = I; Y = Cl, Br, I) (Kukkonen et al., 2019; Batsanov et al., 2005, 2006). In addition, N-protonated pyridinium cations were obtained, whose charge can be counterbalanced by discrete halides or extended fascinating networks (Aragoni et al., 2004; Aragoni et al., 2023). Oxidation of the aromatic heterocycle to give a cationic radical species followed by solvolysis or reaction with incipient moisture has been proposed as a possible explanation for the formation of pyridinium cations (Rimmer et al., 1998; Aragoni et al., 2023).

The nature of the products isolated in the solid state is reflected in their peculiar FT–Raman response (Aragoni et al., 2004, 2008; Pandeeswaran et al., 2009). In particular, an elongation of the perturbed X–Y moiety with respect to the free halogen/inter­halogen is found in CT-adducts, which determines a low energy shift of the relevant Raman-active stretching vibration (Aragoni et al., 2008). When polyhalide networks are formed, the stretching vibrations of the inter­acting synthons can be detected in the low-energy region of the FT–Raman spectrum (Aragoni et al., 2008, 2023).

Di­sulfides are an important class of organic compounds with a variety of biological and pharmacological applications (Sevier & Kaiser, 2002; Lee et al., 2013), in particular due to their anti­oxidant and prooxidant properties (Zhu et al., 2023). It is well known that the dibromine and dichlorine oxidation of di­aryl­disulfides leads to the cleavage of the sulfur–sulfur bond (Zincke reaction; Zincke,1911; Baker et al., 1946), whereas the reaction of di­sulfides with the mildest oxidant, diiodine, does not involve the cleavage of the S—S bond (Aragoni et al., 2023). The reaction of 2,2′-di­pyridyl­disulfide (L) with I₂ in CH₂Cl₂ afforded the compound [(HL⁺)(I⁻)·5/2I₂]_∞, featuring an unusual polyiodide network counterbalancing the N-monoprotonated HL⁺ cation. Recently, an assembly isostructural to [(HL⁺)(I⁻)·5/2I₂]_∞ was obtained by reacting 2,2′-di­pyridyl­diselenide with I₂ in either CH₂Cl₂ or CH₃CN (Aragoni et al., 2023).

Although 4,4′-di­pyridyl­disulfide (L′) has been widely reported as a donor towards a variety of metal ions (Sarkar et al., 2016; Zheng et al., 2022, 2023; Singha et al., 2018), its reactivity towards halogens or inter­halogens has been only marginally explored (Wzgarda-Raj et al., 2021; Coe et al., 1997). An example is provided by 4,4′-(disulfanedi­yl)dipyridinium penta­iodide triiodide (CSD code OXAFIF; Wzgarda-Raj et al., 2021) where the cation H₂L′²⁺ is counterbalanced by a polyiodide built up of inter­acting I₃⁻ and I₅⁻ ions.

Following our investigation on the reactivity of polypyridyl substrates towards ICl (Aragoni et al., 2008), we report here on the structural and spectroscopic characterization of the novel salt 4,4′-disulfanediyldipyridinium chloride triiodide (1).

2. Structural commentary

By reacting 4,4′-di­pyridyl­disulfide (L′) and ICl in 1:1 molar ratio, product 1 was isolated and characterized by elemental analysis, melting point determination, FT–IR, and FT–Raman spectroscopy. Single-crystal X-ray diffraction analysis established 1 as (H₂L′²⁺)(Cl⁻)(I₃⁻) (Fig. 1).

Figure 1 Ellipsoid plot of compound 1 with the numbering scheme adopted. Displacement ellipsoids are drawn at the 50% probability level. Labelled inter­actions are described according to Table 1.

Compound 1 crystallizes in the monoclinic space group P2₁/c with four (H₂L′²⁺)(Cl⁻)(I₃⁻) units in the unit cell. The asymmetric unit of compound 1 consists of a donor mol­ecule protonated at both the N1 and N2 pyridine nitro­gen atoms H₂L′²⁺ counterbalanced by a chloride and a triiodide I₃⁻ anions. In the H₂L′²⁺ cation, the two pyridine rings are almost perpendicular [C1—S1—S2—C6 torsion angle = 89.4 (1)°], being rotated by 2.7 (3) and 19.8 (3)° with respect to the respective C–S–S plane. The linear triiodide anion [I1—I2—I3 = 177.13 (1)°] is remarkably asymmetric with a very short I1—I2 distance [2.8180 (4) Å], close to the I—I distance of solid-state iodine (2.715 Å; van Bolhuis et al. 1967), and a longer one [I2—I3 = 3.0459 (4) Å], in agreement to the three-body system of the I₃⁻ anion, showing a correlation between the two I—I distances. Accordingly, the I1—I2 and I2—I3 bond distances fall in the correlation reported by Devillanova (Aragoni et al., 2012) featured by I_A–I_B–I_C systems, which correlates the relative elongations of the two I_A—I_B and I_C—I_D lengths with respect to the the sum of the relevant covalent radii.

3. Supra­molecular features

The protonated pyridine rings of the H₂L′²⁺ cation are involved in hydrogen-bonding (HB) inter­actions with the chloride anions (inter­action a in Fig. 1; a and c in Fig. 2 and Table 1), thus forming a wavy 1-D hydrogen-bonded polymeric structure that develops perpendicular to the b-axis. In addition, each chloride inter­acts with a terminal iodine atom of a triiodide [I1⋯Cl1 = 3.4764 (8) Å; inter­action b in Figs. 1 and 2 and Table 1] at a distance shorter than the sum of the relevant van der Waals radii (3.73 Å; Bondi, 1964), so that the chloride and the triiodide could be considered to form a [I⋯I–I⋯Cl]^2– dianionic ensemble, unprecedented among the relevant polyinter­halides (Sonnenberg et al., 2020) deposited at the Cambridge Structural Database (CSD, version 5.45 update 1, March 2024; Groom et al., 2016). Nevertheless, the Cl⋯I distance is longer than those previously reported for the parent [I₂Cl]⁻ anion [for example I⋯Cl = 3.158, 3.047 Å in the structures with CSD codes BEQXEA (Wang et al. 1999) and BOJYIL (Pan et al. 2019), respectively] and [Cl₂I₂]^2– dianions [3.070 and 3.242 Å in DOXDOL (Buist & Kennedy, 2014) and JUPCAA (Pan et al. 2015), respectively]. These Cl⋯I inter­actions, shown in Fig. 2, which fall into the realm of halogen bonding (XB) inter­actions, generate the crystal packing along with a set of weak C—H⋯I contacts (entries d–g in Table 1).

Table 1
Inter­molecular inter­actions (Å, °) of compound 1

Inter­action		A—B	B⋯C	A⋯C	A—B⋯C
a	N1—H1⋯Cl1	0.82 (3)	2.41 (3)	3.101 (2)	142 (2)
b	I2—I1⋯Cl1	2.8179 (4)	3.4764 (8)	–	173.93 (2)
c	N2^i—H2^i⋯Cl1	0.81 (4)	2.21 (4)	3.006 (3)	168
d	C10—H10⋯I3^ii	0.95	3.07	3.833 (3)	138
e	C9—H9⋯I2^ii	0.95	3.18	4.108 (4)	166
f	C7—H7⋯I2^iii	0.95	3.03	3.738 (4)	132
g	C7—H7⋯I3^iii	0.95	3.14	3.801 (3)	129
Symmetry codes: (i) −1 + x,  − y, − + z; (ii) 2 − x, 2 − y, 1 − z; (iii) x,  − y,  + z.

Figure 2 Section of the crystal packing of compound 1 viewed along the c-axis. Labelled contacts are described in Table 1.

4. Conclusions

4,4′-Disulfanediyldipyridinium chloride triiodide (H₂L′²⁺)(Cl⁻)(I₃⁻)(1) was synthesized and characterized structurally and spectroscopically. The isolation of 1 confirms that L′ is not susceptible to the oxidative cleavage of the S—S di­sulfide bond by diiodine and iodine monochloride under mild conditions, but that it can undergo protonation and template fascinating supra­molecular structures, as previously observed in the case of [(HL⁺)(I⁻)·5/2I₂]_∞. Further studies are ongoing in our laboratory to investigate the reactivity of different di­pyridyl­dichalcogenides towards dihalogens and inter­halogens and their versatility as building blocks for extended supra­molecular assemblies based on σ-hole inter­actions.

5. Synthesis and crystallization

5.1. Materials and methods

All the reagents and solvents were used without further purification. Elemental analysis determinations were performed with an EA1108 CHNS-O Fisons instrument. Fourier-Transform Infrared (FT–IR) spectroscopic measurements were recorded on a Bruker IFS55 spectrometer at room temperature using a flow of dried air. Far-infrared (FIR; 500–50 cm⁻¹) spectra were recorded on polythene pellets using a Mylar beam-splitter and polythene windows (resolution 2 cm⁻¹). Middle-infrared (MIR) spectra were recorded on KBr pellets, with a KBr beam-splitter and KBr windows (resolution 2 cm⁻¹). FT-Raman spectroscopy measurements were recorded on a Bruker RFS100 spectrometer (resolution of 2 cm⁻¹), with an In–Ga–As detector operating with a Nd:YAG laser (λ = 1064 nm) with a 180° scattering geometry (excitation power 5 mW). Melting point determinations were carried out on a FALC mod. C apparatus.

5.2. Synthesis of compound 1

To 2 mL of a CH₂Cl₂ solution of 4,4′-di­pyridyl­disulfide (19 mg, 8.6·10⁻⁵ mol), a 0.054 mol L⁻¹ solution of ICl in the same solvent was added dropwise in donor/ICl in a 1:1 molar ratio. A brown crystalline precipitate was isolated from the mother liquor by air-evaporation and washed with light petroleum ether. A small number of crystals were placed on a glass slide and coated with a perfluoro­ether oil. A crystal suitable for X-ray diffraction analysis was selected and mounted on a glass fibre. Elemental analysis calculated for C₁₀H₁₀N₂S₂I₃Cl: 18.81; H, 1.57; N, 4.38; S, 10.04%. Found: C, 18.63; H, 1.78; N, 4.09, S 9.98%. M.p. > 513 K. FT–MIR (KBr pellet, 4000–400 cm⁻¹): 3854s, 3460s, 3437s, 3088s, 2743s, 2363s, 1952s, 1846s, 1773m, 1653s, 1603s, 1589s, 1558m, 1441s, 1371s, 1277s, 1086m, 1034m, 997m, 951m, 783m, 773s, 617s, 498m cm⁻¹. FT–FIR (polythene pellet, 500–50 cm^­–1): 484m, 477m, 449w, 418m, 390w, 378m, 352m, 294w, 256m, 227s, 170s, 131m, 94m, 67m cm⁻¹. FT–Raman (500–50 cm⁻¹, 5 mW, relative intensities in parentheses related to the highest peak taken equal to 10.0): 267(0.7), 155 (2.2), 137 (3.0), 113 (10.0) cm⁻¹.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms bonded to heteroatoms could be located from difference-Fourier maps and their positions were freely refined. Other H atoms were placed in geometrically calculated positions and were constrained to ride on their parent atom with C—H = 0.95 Å and with U_iso(H) = 1.2U_eq(C).

Table 2
Experimental details

Crystal data
Chemical formula	C10H10N2S2^2+·Cl^−·I3^−
Mr	638.47
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	120
a, b, c (Å)	12.9631 (11), 11.3802 (5), 13.1675 (11)
β (°)	117.624 (6)
V (Å^3)	1721.1 (2)
Z	4
Radiation type	Mo Kα
μ (mm^−1)	5.83
Crystal size (mm)	0.32 × 0.22 × 0.06
Data collection
Diffractometer	Bruker-Nonius 95mm CCD camera on κ-goniostat
Absorption correction	Multi-scan (SADABS; Krause et al., 2015)
Tmin, Tmax	0.632, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	16769, 3959, 3621
Rint	0.027
(sin θ/λ)max (Å^−1)	0.651
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.022, 0.046, 1.13
No. of reflections	3959
No. of parameters	170
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å^−3)	0.74, −0.80
Computer programs: DENZO (Otwinowski & Minor, 1997) & COLLECT (Hooft, 1998), SHELXT2018/2 (Sheldrick, 2015a), SHELXL2018/3 (Sheldrick, 2015b) and OLEX2 (Dolomanov et al., 2009).

Supporting information

Computing details

4,4'-(Disulfanediyl)dipyridinium chloride triiodide

Crystal data

C10H10N2S2^2+·Cl^−·I3^−	F(000) = 1168
Mr = 638.47	Dx = 2.464 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 12.9631 (11) Å	Cell parameters from 17448 reflections
b = 11.3802 (5) Å	θ = 2.9–27.5°
c = 13.1675 (11) Å	µ = 5.83 mm^−1
β = 117.624 (6)°	T = 120 K
V = 1721.1 (2) Å^3	Cut-plate, brown
Z = 4	0.32 × 0.22 × 0.06 mm

Data collection

Bruker-Nonius 95mm CCD camera on κ-goniostat diffractometer	3621 reflections with I > 2σ(I)
Detector resolution: 9.091 pixels mm^-1	Rint = 0.027
φ & ω scans	θmax = 27.6°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −16→16
Tmin = 0.632, Tmax = 1.000	k = −14→14
16769 measured reflections	l = −16→17
3959 independent reflections

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)] = 0.022	w = 1/[σ^2(Fo^2) + (0.0127P)^2 + 2.0409P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.046	(Δ/σ)max = 0.003
S = 1.13	Δρmax = 0.74 e Å^−3
3959 reflections	Δρmin = −0.80 e Å^−3
170 parameters	Extinction correction: SHELXL2018/3 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00091 (7)
Primary atom site location: dual

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
I1	0.67827 (2)	1.09634 (2)	0.41894 (2)	0.01952 (7)
I2	0.91260 (2)	1.16703 (2)	0.50892 (2)	0.01704 (6)
I3	1.16454 (2)	1.24311 (2)	0.59403 (2)	0.01907 (7)
Cl1	0.39992 (6)	0.98349 (6)	0.32707 (6)	0.01852 (15)
S2	0.78491 (6)	0.37523 (6)	0.66898 (6)	0.01882 (16)
S1	0.68199 (6)	0.41735 (6)	0.50222 (6)	0.01885 (16)
N2	1.1441 (2)	0.4996 (2)	0.7561 (2)	0.0192 (5)
H2	1.211 (3)	0.515 (3)	0.773 (3)	0.023*
N1	0.5417 (2)	0.7795 (2)	0.4871 (2)	0.0199 (5)
H1	0.516 (3)	0.847 (3)	0.477 (3)	0.024*
C6	0.9235 (2)	0.4272 (2)	0.6967 (2)	0.0158 (6)
C7	1.0175 (3)	0.3800 (3)	0.7912 (2)	0.0177 (6)
H7	1.005658	0.321243	0.836033	0.021*
C8	1.1276 (3)	0.4183 (3)	0.8198 (2)	0.0184 (6)
H8	1.192339	0.386896	0.885121	0.022*
C10	0.9433 (3)	0.5117 (3)	0.6312 (3)	0.0218 (6)
H10	0.880332	0.545123	0.565665	0.026*
C9	1.0561 (3)	0.5457 (3)	0.6637 (3)	0.0221 (6)
H9	1.071345	0.602813	0.619735	0.027*
C1	0.6298 (2)	0.5595 (2)	0.5052 (2)	0.0152 (6)
C5	0.5599 (3)	0.6079 (3)	0.3976 (3)	0.0198 (6)
H5	0.542253	0.564513	0.329894	0.024*
C2	0.6521 (2)	0.6235 (3)	0.6030 (2)	0.0180 (6)
H2A	0.698461	0.591158	0.676964	0.022*
C3	0.6063 (3)	0.7340 (3)	0.5911 (3)	0.0223 (7)
H3	0.620692	0.778684	0.657258	0.027*
C4	0.5170 (3)	0.7196 (3)	0.3912 (3)	0.0209 (6)
H4	0.469740	0.754210	0.318565	0.025*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.01655 (11)	0.02240 (11)	0.02038 (11)	0.00155 (7)	0.00921 (9)	0.00205 (8)
I2	0.01911 (11)	0.01738 (10)	0.01659 (11)	0.00135 (7)	0.00995 (8)	0.00154 (7)
I3	0.01743 (11)	0.02150 (11)	0.01500 (11)	−0.00096 (7)	0.00473 (8)	−0.00102 (7)
Cl1	0.0157 (3)	0.0192 (3)	0.0216 (4)	0.0040 (3)	0.0095 (3)	0.0045 (3)
S2	0.0134 (4)	0.0209 (3)	0.0225 (4)	0.0021 (3)	0.0086 (3)	0.0052 (3)
S1	0.0150 (4)	0.0173 (3)	0.0196 (4)	0.0037 (3)	0.0042 (3)	−0.0033 (3)
N2	0.0117 (12)	0.0193 (12)	0.0274 (14)	−0.0021 (10)	0.0098 (11)	−0.0063 (11)
N1	0.0167 (13)	0.0164 (12)	0.0264 (14)	0.0037 (10)	0.0099 (11)	0.0005 (11)
C6	0.0150 (14)	0.0162 (13)	0.0173 (14)	0.0015 (11)	0.0083 (12)	−0.0029 (11)
C7	0.0193 (15)	0.0203 (14)	0.0148 (14)	0.0041 (12)	0.0091 (12)	0.0013 (12)
C8	0.0148 (15)	0.0221 (14)	0.0165 (14)	0.0033 (11)	0.0056 (12)	−0.0029 (12)
C10	0.0186 (16)	0.0207 (15)	0.0225 (15)	0.0042 (12)	0.0064 (13)	0.0084 (12)
C9	0.0205 (16)	0.0199 (14)	0.0282 (17)	−0.0015 (12)	0.0131 (14)	0.0028 (13)
C1	0.0084 (13)	0.0163 (13)	0.0187 (14)	−0.0010 (10)	0.0043 (11)	−0.0023 (11)
C5	0.0175 (15)	0.0221 (15)	0.0177 (15)	0.0029 (12)	0.0064 (12)	−0.0027 (12)
C2	0.0153 (15)	0.0191 (14)	0.0147 (14)	0.0007 (11)	0.0027 (12)	0.0000 (12)
C3	0.0200 (16)	0.0199 (14)	0.0229 (16)	−0.0006 (12)	0.0065 (13)	−0.0079 (13)
C4	0.0194 (16)	0.0228 (15)	0.0207 (15)	0.0036 (12)	0.0094 (13)	0.0043 (13)

Geometric parameters (Å, º)

I1—I2	2.8180 (4)	C7—C8	1.368 (4)
I2—I3	3.0459 (4)	C8—H8	0.9500
S2—S1	2.0285 (11)	C10—H10	0.9500
S2—C6	1.762 (3)	C10—C9	1.375 (4)
S1—C1	1.762 (3)	C9—H9	0.9500
N2—H2	0.81 (3)	C1—C5	1.394 (4)
N2—C8	1.331 (4)	C1—C2	1.387 (4)
N2—C9	1.330 (4)	C5—H5	0.9500
N1—H1	0.82 (3)	C5—C4	1.374 (4)
N1—C3	1.334 (4)	C2—H2A	0.9500
N1—C4	1.337 (4)	C2—C3	1.368 (4)
C6—C7	1.384 (4)	C3—H3	0.9500
C6—C10	1.393 (4)	C4—H4	0.9500
C7—H7	0.9500
I1—I2—I3	177.129 (8)	C9—C10—H10	120.8
C6—S2—S1	103.93 (10)	N2—C9—C10	120.7 (3)
C1—S1—S2	105.03 (10)	N2—C9—H9	119.6
C8—N2—H2	116 (2)	C10—C9—H9	119.6
C9—N2—H2	122 (2)	C5—C1—S1	114.5 (2)
C9—N2—C8	122.0 (3)	C2—C1—S1	125.9 (2)
C3—N1—H1	123 (2)	C2—C1—C5	119.6 (3)
C3—N1—C4	122.1 (3)	C1—C5—H5	120.6
C4—N1—H1	115 (2)	C4—C5—C1	118.8 (3)
C7—C6—S2	116.4 (2)	C4—C5—H5	120.6
C7—C6—C10	119.1 (3)	C1—C2—H2A	120.6
C10—C6—S2	124.5 (2)	C3—C2—C1	118.9 (3)
C6—C7—H7	120.2	C3—C2—H2A	120.6
C8—C7—C6	119.6 (3)	N1—C3—C2	120.5 (3)
C8—C7—H7	120.2	N1—C3—H3	119.8
N2—C8—C7	120.0 (3)	C2—C3—H3	119.8
N2—C8—H8	120.0	N1—C4—C5	120.1 (3)
C7—C8—H8	120.0	N1—C4—H4	120.0
C6—C10—H10	120.8	C5—C4—H4	120.0
C9—C10—C6	118.4 (3)
S2—S1—C1—C5	177.6 (2)	C7—C6—C10—C9	−0.4 (4)
S2—S1—C1—C2	−2.7 (3)	C8—N2—C9—C10	0.9 (4)
S2—C6—C7—C8	−178.3 (2)	C10—C6—C7—C8	1.1 (4)
S2—C6—C10—C9	178.9 (2)	C9—N2—C8—C7	−0.2 (4)
S1—S2—C6—C7	−160.8 (2)	C1—C5—C4—N1	−0.5 (4)
S1—S2—C6—C10	19.9 (3)	C1—C2—C3—N1	−0.2 (4)
S1—C1—C5—C4	−178.7 (2)	C5—C1—C2—C3	−1.2 (4)
S1—C1—C2—C3	179.1 (2)	C2—C1—C5—C4	1.5 (4)
C6—C7—C8—N2	−0.8 (4)	C3—N1—C4—C5	−0.9 (5)
C6—C10—C9—N2	−0.5 (4)	C4—N1—C3—C2	1.3 (5)