Poly[(μ4-5,7-di­hydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine-κ4N:N′:S:S′)tetra-μ3-iodido-tetra­copper]: a three-dimensional copper(I) coordination polymer

Assoumatine, T.; Stoeckli-Evans, H.

doi:10.1107/S2414314620004010

metal-organic compounds

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ISSN: 2414-3146

Volume 5| Part 3| March 2020| x200401

https://doi.org/10.1107/S2414314620004010

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Poly[(μ₄-5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine-κ⁴N:N′:S:S′)tetra-μ₃-iodido-tetracopper]: a three-dimensional copper(I) coordination polymer

Tokouré Assoumatine ^a and Helen Stoeckli-Evans ^b ^*

^aInstitute of Chemistry, University of Neuchâtel, Av. de Bellevax 51, CH-2000 Neuchâtel, Switzerland, and ^bInstitute of Physics, University of Neuchâtel, rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
^*Correspondence e-mail: helen.stoeckli-evans@unine.ch

Edited by A. J. Lough, University of Toronto, Canada (Received 17 March 2020; accepted 21 March 2020; online 27 March 2020)

The reaction of ligand 5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine (L) with CuI lead to the formation of a three-dimensional coordination polymer, incorporating the well known [Cu_xI_x]_n staircase motif (x = 4). These polymer [Cu₄I₄]_n chains are linked via the N and S atoms of the ligand to form the three-dimensional coordination polymer poly[(μ₄-5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine-κ⁴N:N′:S:S′)tetra-μ₃-iodido-tetracopper], [Cu₄I₄(C₈H₈N₂S₂)]_n (I). The asymmetric unit is composed of half a ligand molecule, with the pyrazine ring located about a center of symmetry, and two independent copper(I) atoms and two independent I⁻ ions forming the staircase motif via centers of inversion symmetry. The framework is consolidated by C—H⋯I hydrogen bonds.

Keywords: crystal structure; copper(I) iodide; pyrazine; pyrazinethiophane; three-dimensional coordination polymer; framework.

CCDC reference: 1991908

Structure description

We have recently shown that the reaction of the ligand 5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine (L), with silver(I) nitrate leads to the formation of a two-dimensional coordination polymer, with the silver atom coordinating only to the S atoms of the ligand so forming chains. The nitrato anion bridges two equivalent silver atoms and so generates the network structure (Assoumatine & Stoeckli-Evans, 2020a ). Ligand L is one of a series of pyrazinethiophanes synthesized to study their coordination chemistry with various transition metals (Assoumatine, 1999 ). The reaction of L with CuCl₂ and CuBr₂ lead to the formation of isostructural one-dimensional coordination polymers with the ligand coordinating to the copper atom via the N atoms only (Assoumatine & Stoeckli-Evans, 2020b ).

The reaction of L with CuI has lead to the formation of a three-dimensional coordination polymer, incorporating the well known [Cu_xI_x]_n staircase motif (x = 4; Fig. 1). The asymmetric unit is composed of half a ligand molecule, with the pyrazine ring located about a center of symmetry, and two independent copper(I) atoms and two independent I⁻ ions forming the staircase motif via centers of inversion symmetry. The polymer [Cu₄I₄]_n chains are linked via the N and S atoms of the ligand to form the three-dimensional framework of complex I (Fig. 2).

Figure 1
A partial view of the molecular structure of complex I, with atom labelling for the atoms of the asymmetric unit. Displacement ellipsoids are drawn at the 30% probability level. Colour code: Cu1 orange, Cu2 green, I1 purple, I2 violet.

Figure 2
A view along the a axis of the crystal packing of complex I. For clarity, the H atoms have been omitted.

In the ligand, the five-membered thiophene rings are not planar, but have envelope configurations with the S atom as the flap. Atom S1 deviates by 0.5076 (14) Å from the mean plane of the four C atoms (C1–C4). This is considerably more than in the silver(I) nitrate two-dimensional coordination polymer or the ligand itself (Assoumatine & Stoeckli-Evans, 2020a). In the former, the S atom deviates from the mean plane of the four C atoms by 0.170 (15) Å, and in the latter by only 0.0256 (8) Å.

Selected bond lengths and bond angles involving the copper(I) atoms in I are given in Table 1. In I, both copper(I) atoms are fourfold coordinate; the Cu⋯Cu distances are not considered as bonds. Hence, atom Cu1 has a fourfold CuSI₃ coordination geometry with the fourfold index parameter τ₄ = 0.91 (τ₄ = 1 for a perfect tetrahedral geometry, 0 for a perfect square-planar geometry and 0.85 for perfect trigonal–pyramidal geometry; Yang et al., 2007 ). Atom Cu2 has a CuNI₃ coordination geometry with a fourfold index parameter τ₄ = 0.88. Hence, both atoms have similar distorted shapes, neither perfect tetrahedral nor perfect trigonal–pyramidal. The Cu—N, Cu—S and Cu—I bond lengths are within normal values and are discussed below.

Table 1
Selected geometric parameters (Å, °)

Cu1—Cu1ⁱ	2.7355 (16)	I2—Cu1ⁱⁱ	2.6617 (10)
Cu1—Cu2ⁱⁱ	2.9030 (14)	Cu2—N1^iv	2.059 (4)
Cu1—S1	2.3393 (16)	I1—Cu2ⁱⁱ	2.6786 (9)
I1—Cu1	2.6477 (9)	I1—Cu2	2.7142 (9)
I2—Cu1ⁱⁱⁱ	2.6478 (11)	I2—Cu2	2.6418 (8)

S1—Cu1—I1	104.34 (4)	N1^iv—Cu2—I2	107.06 (12)
S1—Cu1—I2^v	108.74 (5)	N1^iv—Cu2—I1ⁱⁱ	122.19 (13)
I1—Cu1—I2^v	107.06 (3)	I2—Cu2—I1ⁱⁱ	113.30 (3)
S1—Cu1—I2ⁱⁱ	104.10 (5)	N1^iv—Cu2—I1	110.69 (13)
I1—Cu1—I2ⁱⁱ	113.66 (3)	I2—Cu2—I1	108.98 (3)
I2^v—Cu1—I2ⁱⁱ	117.98 (3)	I1ⁱⁱ—Cu2—I1	93.48 (3)
Symmetry codes: (i) -x+2, -y, -z+2; (ii) -x+1, -y, -z+2; (iii) x-1, y, z; (iv) -x+2, -y+1, -z+2; (v) x+1, y, z.

In the crystal of I, the three-dimensional structure is consolidated by C—H⋯I hydrogen bonds (Table 2).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3B⋯I1	0.97	3.01	3.808 (6)	140
C3—H3A⋯I1^vi	0.97	2.91	3.767 (5)	149
C4—H4A⋯I1^iv	0.97	3.00	3.641 (5)	124
Symmetry codes: (iv) -x+2, -y+1, -z+2; (vi) -x+1, -y, -z+1.

There are less than 15 polymeric structures in the Cambridge Structural Database (CSD; Version 5.41, last update November 2019; Groom et al., 2016 ) that concern pyrazine ligands and the [Cu_xI_x]_n staircase motif (see file S1 in the supporting information). The majority form two-dimensional coordination polymers with the pyrazine ligand bridging the [Cu_xI_x]_n chains. For example, catena-[bis(μ₃-iodo)(μ₂-pyrazine-N,N′)dicopper(I)] (CSD refcode AGIYEU01 at 203 K; Blake et al., 1999 ) and catena-[bis(μ₃-iodo)(μ₃-bis(6-methylpyrazin-2-ylmethyl)thioether-N,N′,N′′,S)(μ₂-iodo)tricopper(I)] (RABBUS at 123 K; Amoore et al., 2003 ). In AGIYEU01, the copper atom has a CuNI₃ fourfold coordination geometry with a τ₄ index parameter of 0.90. In the case of RABBUS, there are three copper(I) atoms. Two of the copper atoms have CuNI₃ fourfold coordination geometries with τ₄ index parameters of 0.92 and 0.89. The third copper atom has a CuNSI₂ fourfold coordination geometry with a τ₄ index parameter of 0.73. In comparison, the τ₄ index parameters for the two copper atoms in I are 0.91 and 0.85.

In AGIYEU01, the Cu—N_pyrazine bond length is 2.028 (9) Å. In RABBUS the copper(I) atoms coordinate to the pyrazine N atoms and the S atom of the ligand. Here, the Cu—N_pyrazine bond lengths are 2.053 (4), 2.070 (4) and 2.071 (4) Å and the Cu—S bond length is 2.3574 (15) Å. In I, the Cu2—N^iv and Cu1—S1 bond lengths of 2.059 (4) and 2.3393 (16) Å, respectively, are very similar to those sited above. The Cu—I bond lengths involving the [Cu_xI_x]_n staircase motifs are very similar in all three compounds; they vary from 2.6131 (15) to 2.6485 (15) Å in AGIYEU01, from 2.5993 (7) to 2.8348 (7) Å in RABBUS, and from 2.6418 (8) to 2.7142 (9) Å in I. The Cu⋯Cu distances in I, Cu1—Cu1ⁱ = 2.7355 (16) Å and Cu1—Cu2ⁱⁱ = 2.9030 (14) Å, are similar to those in AGIYEU01 [2.7562 (19) Å] and RABUSS [2.6546 (8), 2.7565 (9) and 2.9256 (8) Å].

Synthesis and crystallization

The synthesis and crystal structure of the ligand 5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine (L), have been reported (Assoumatine & Stoeckli-Evans, 2020a).

Synthesis of compound I: A solution of L (15 mg, 0.08 mmol) in CH₂Cl₂ (10 ml) was introduced into a 16 mm diameter glass tube and layered with MeCN (2 ml) as a buffer zone. Then a solution of CuI (15 mg, 0.08 mmol) in MeCN (5 ml) was added very gently to avoid possible mixing. The glass tube was sealed under an atmosphere of nitrogen and left in the dark at room temperature for at least 2 weeks, whereupon deep-orange plate-like crystals of the title compound, (I), were isolated in the buffer zone. Analysis for C₈H₈N₂S₂Cu₄I₄ (M_r = 958.14 g mol⁻¹): calculated (%): C 10.03, H 0.84, N 2.92, S 6.69; found (%): C 10.12, H 0.80, N 2.82, S 6.67. The IR spectrum is shown in Fig. S1 of the supporting information.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. A Stoe IPDS-I one-circle diffractometer was used for the data collection at RT. With this instrument for the triclinic system often a small cusp of data is inaccessible; here 176 reflections which gives the alert diffrn_reflns_laue_measured_fraction_full value (0.889) below minimum (0.95). The effect here appears to be limited if one compares the bond lengths in the structure of the pure ligand (Assoumatine & Stoeckli-Evans, 2020a) with those of the ligand in complex I; they are the same within 3 s.u.s.

Table 3
Experimental details

Crystal data
Chemical formula	[Cu₄I₄(C₈H₈N₂S₂)]
M_r	958.04
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	293
a, b, c (Å)	7.0082 (8), 8.378 (1), 8.8162 (10)
α, β, γ (°)	102.808 (13), 104.607 (13), 109.369 (13)
V (Å³)	445.35 (10)
Z	1
Radiation type	Mo Kα
μ (mm⁻¹)	11.87
Crystal size (mm)	0.50 × 0.35 × 0.13

Data collection
Diffractometer	Stoe IPDS1
Absorption correction	Multi-scan (MULABS; Spek, 2020 )
T_min, T_max	0.188, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	3272, 1515, 1452
R_int	0.038
(sin θ/λ)_max (Å⁻¹)	0.612

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.040, 0.103, 1.10
No. of reflections	1515
No. of parameters	92
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.73, −1.58
Computer programs: EXPOSE, CELL and INTEGRATE in IPDS-I (Stoe & Cie, 1998 ), SHELXS97 (Sheldrick, 2008 ), Mercury (Macrae et al., 2020 ), SHELXL2018 (Sheldrick, 2015 ), PLATON (Spek, 2020) and publCIF (Westrip, 2010 ).

The residual electron-density peaks, Δρ_max = 1.73 e Å⁻³, and Δρ_min = −1.58 e Å⁻³, are located near the iodine atoms (within 0.80 to 1.13 Å). As stated by Spek (2018 ): `they can be interpreted as absorption artefacts due to insufficient or incorrect correction for absorption'; the T_min and T_max values of 0.188 and 1.000, respectively, are rather extreme. However, in our experience high residual electron-density peaks are often observed for compounds containing heavy atoms such as iodine.

Structural data

CCDC reference: 1991908

Crystal structure: contains datablocks I, Global. DOI: https://doi.org/10.1107/S2414314620004010/lh4055sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620004010/lh4055Isup2.hkl

CSD search. DOI: https://doi.org/10.1107/S2414314620004010/lh4055sup3.pdf

The IR spectrum. DOI: https://doi.org/10.1107/S2414314620004010/lh4055sup4.tif

checkCIF report

Computing details top

Data collection: EXPOSE in IPDS-I (Stoe & Cie, 1998); cell refinement: CELL in IPDS-I (Stoe & Cie, 1998); data reduction: INTEGRATE in IPDS-I (Stoe & Cie, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: SHELXL2018 (Sheldrick, 2015), PLATON (Spek, 2020) and publCIF (Westrip, 2010).

Poly[(µ₄-5,7-dihydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine-κ⁴N:N':S:S')tetra-µ₃-iodido-tetracopper] top

Crystal data top

[Cu₄I₄(C₈H₈N₂S₂)]	Z = 1
M_r = 958.04	F(000) = 430
Triclinic, P1	D_x = 3.572 Mg m⁻³
a = 7.0082 (8) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.378 (1) Å	Cell parameters from 5000 reflections
c = 8.8162 (10) Å	θ = 3.3–25.8°
α = 102.808 (13)°	µ = 11.87 mm⁻¹
β = 104.607 (13)°	T = 293 K
γ = 109.369 (13)°	Plate, orange
V = 445.35 (10) Å³	0.50 × 0.35 × 0.13 mm

Data collection top

Stoe IPDS-1 diffractometer	1515 independent reflections
Radiation source: fine-focus sealed tube	1452 reflections with I > 2σ(I)
Plane graphite monochromator	R_int = 0.038
φ rotation scans	θ_max = 25.8°, θ_min = 3.3°
Absorption correction: multi-scan (MULABS; Spek, 2020)	h = −8→8
T_min = 0.188, T_max = 1.000	k = −10→10
3272 measured reflections	l = −10→10

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.040	H-atom parameters constrained
wR(F²) = 0.103	w = 1/[σ²(F_o²) + (0.0717P)² + 0.7287P] where P = (F_o² + 2F_c²)/3
S = 1.10	(Δ/σ)_max < 0.001
1515 reflections	Δρ_max = 1.73 e Å⁻³
92 parameters	Δρ_min = −1.58 e Å⁻³
0 restraints	Extinction correction: (SHELXL2018; Sheldrick, 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.016 (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
I1	0.57925 (5)	0.17176 (5)	0.88315 (4)	0.0210 (2)
I2	0.21064 (6)	0.27610 (5)	1.19497 (4)	0.0241 (2)
Cu1	0.90704 (13)	0.07739 (12)	0.89969 (10)	0.0309 (3)
Cu2	0.53098 (11)	0.18093 (10)	1.18047 (9)	0.0261 (2)
S1	1.0313 (2)	0.16243 (17)	0.69503 (15)	0.0198 (3)
N1	1.1948 (7)	0.6290 (6)	0.6269 (5)	0.0153 (9)
C1	0.9013 (8)	0.3374 (7)	0.5075 (6)	0.0157 (10)
C2	1.0949 (8)	0.4665 (7)	0.6316 (6)	0.0173 (10)
C3	0.8095 (8)	0.1646 (8)	0.5351 (6)	0.0227 (12)
H3A	0.759686	0.064557	0.433563	0.027*
H3B	0.689123	0.157278	0.572613	0.027*
C4	1.1768 (9)	0.4053 (7)	0.7736 (6)	0.0235 (11)
H4A	1.146935	0.457309	0.869883	0.028*
H4B	1.331493	0.439565	0.804763	0.028*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
I1	0.0227 (3)	0.0192 (3)	0.0175 (3)	0.00881 (19)	0.00387 (17)	0.00296 (18)
I2	0.0207 (3)	0.0222 (3)	0.0265 (3)	0.0103 (2)	0.00545 (18)	0.00384 (18)
Cu1	0.0322 (4)	0.0328 (5)	0.0296 (4)	0.0143 (4)	0.0077 (3)	0.0158 (3)
Cu2	0.0223 (4)	0.0226 (4)	0.0229 (4)	0.0062 (3)	0.0000 (3)	0.0025 (3)
S1	0.0224 (6)	0.0158 (7)	0.0185 (6)	0.0074 (5)	0.0034 (5)	0.0057 (5)
N1	0.0137 (18)	0.018 (2)	0.0127 (19)	0.0066 (17)	0.0032 (15)	0.0036 (16)
C1	0.015 (2)	0.015 (2)	0.016 (2)	0.005 (2)	0.0047 (18)	0.0048 (19)
C2	0.017 (2)	0.020 (3)	0.014 (2)	0.010 (2)	0.0030 (19)	0.004 (2)
C3	0.020 (3)	0.026 (3)	0.016 (2)	0.009 (2)	−0.0015 (19)	0.005 (2)
C4	0.027 (3)	0.016 (3)	0.018 (2)	0.004 (2)	−0.002 (2)	0.006 (2)

Geometric parameters (Å, º) top

Cu1—Cu1ⁱ	2.7355 (16)	S1—C3	1.825 (5)
Cu1—Cu2ⁱⁱ	2.9030 (14)	N1—C2	1.324 (7)
Cu1—S1	2.3393 (16)	N1—C1^v	1.345 (6)
I1—Cu1	2.6477 (9)	C1—C2	1.400 (7)
I2—Cu1ⁱⁱⁱ	2.6478 (11)	C1—C3	1.478 (8)
I2—Cu1ⁱⁱ	2.6617 (10)	C2—C4	1.509 (7)
Cu2—N1^iv	2.059 (4)	C3—H3A	0.9700
I1—Cu2ⁱⁱ	2.6786 (9)	C3—H3B	0.9700
I1—Cu2	2.7142 (9)	C4—H4A	0.9700
I2—Cu2	2.6418 (8)	C4—H4B	0.9700
S1—C4	1.817 (6)

Cu1—I1—Cu2ⁱⁱ	66.05 (3)	I2—Cu2—Cu1ⁱⁱ	57.14 (3)
Cu1—I1—Cu2	103.29 (3)	I1ⁱⁱ—Cu2—Cu1ⁱⁱ	56.46 (3)
Cu2ⁱⁱ—I1—Cu2	86.52 (3)	I1—Cu2—Cu1ⁱⁱ	105.41 (3)
Cu2—I2—Cu1ⁱⁱⁱ	102.73 (3)	C4—S1—C3	93.7 (2)
Cu2—I2—Cu1ⁱⁱ	66.37 (3)	C4—S1—Cu1	107.46 (19)
Cu1ⁱⁱⁱ—I2—Cu1ⁱⁱ	62.02 (3)	C3—S1—Cu1	109.11 (19)
S1—Cu1—I1	104.34 (4)	C2—N1—C1^v	115.3 (4)
S1—Cu1—I2^vi	108.74 (5)	C2—N1—Cu2^iv	121.6 (3)
I1—Cu1—I2^vi	107.06 (3)	C1^v—N1—Cu2^iv	123.0 (4)
S1—Cu1—I2ⁱⁱ	104.10 (5)	N1^v—C1—C2	121.5 (5)
I1—Cu1—I2ⁱⁱ	113.66 (3)	N1^v—C1—C3	122.6 (4)
I2^vi—Cu1—I2ⁱⁱ	117.98 (3)	C2—C1—C3	115.9 (4)
S1—Cu1—Cu1ⁱ	123.23 (6)	N1—C2—C1	123.2 (5)
I1—Cu1—Cu1ⁱ	132.41 (5)	N1—C2—C4	122.9 (5)
I2^vi—Cu1—Cu1ⁱ	59.24 (3)	C1—C2—C4	113.9 (5)
I2ⁱⁱ—Cu1—Cu1ⁱ	58.74 (4)	C1—C3—S1	105.0 (3)
S1—Cu1—Cu2ⁱⁱ	121.87 (5)	C1—C3—H3A	110.7
I1—Cu1—Cu2ⁱⁱ	57.49 (3)	S1—C3—H3A	110.7
I2^vi—Cu1—Cu2ⁱⁱ	129.10 (4)	C1—C3—H3B	110.7
I2ⁱⁱ—Cu1—Cu2ⁱⁱ	56.48 (3)	S1—C3—H3B	110.7
Cu1ⁱ—Cu1—Cu2ⁱⁱ	94.20 (5)	H3A—C3—H3B	108.8
N1^iv—Cu2—I2	107.06 (12)	C2—C4—S1	105.1 (4)
N1^iv—Cu2—I1ⁱⁱ	122.19 (13)	C2—C4—H4A	110.7
I2—Cu2—I1ⁱⁱ	113.30 (3)	S1—C4—H4A	110.7
N1^iv—Cu2—I1	110.69 (13)	C2—C4—H4B	110.7
I2—Cu2—I1	108.98 (3)	S1—C4—H4B	110.7
I1ⁱⁱ—Cu2—I1	93.48 (3)	H4A—C4—H4B	108.8
N1^iv—Cu2—Cu1ⁱⁱ	143.81 (13)

C1^v—N1—C2—C1	−0.7 (8)	N1^v—C1—C3—S1	164.0 (4)
Cu2^iv—N1—C2—C1	176.2 (4)	C2—C1—C3—S1	−16.8 (6)
C1^v—N1—C2—C4	−179.2 (5)	C4—S1—C3—C1	22.5 (4)
Cu2^iv—N1—C2—C4	−2.3 (7)	Cu1—S1—C3—C1	132.4 (3)
N1^v—C1—C2—N1	0.7 (8)	N1—C2—C4—S1	−164.6 (4)
C3—C1—C2—N1	−178.6 (5)	C1—C2—C4—S1	16.7 (6)
N1^v—C1—C2—C4	179.3 (4)	C3—S1—C4—C2	−22.5 (4)
C3—C1—C2—C4	0.1 (7)	Cu1—S1—C4—C2	−133.8 (3)

Symmetry codes: (i) −x+2, −y, −z+2; (ii) −x+1, −y, −z+2; (iii) x−1, y, z; (iv) −x+2, −y+1, −z+2; (v) −x+2, −y+1, −z+1; (vi) x+1, y, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3B···I1	0.97	3.01	3.808 (6)	140
C3—H3A···I1^vii	0.97	2.91	3.767 (5)	149
C4—H4A···I1^iv	0.97	3.00	3.641 (5)	124

Symmetry codes: (iv) −x+2, −y+1, −z+2; (vii) −x+1, −y, −z+1.

Acknowledgements

HSE is grateful to the University of Neuchâtel for their support over the years.

Funding information

Funding for this research was provided by: Swiss National Science Foundation and the University of Neuchâtel.

References

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