Ethyl 5-(4-methyl­phen­yl)-2,4,5,7-tetra­aza­tri­cyclo[6.4.0.02,6]dodeca-1(8),3,6,9,11-penta­ene-3-carboxyl­ate

Moussaif, A.; Ramli, Y.; El Ghayati, L.; Essassi, E.M.; Mague, J.T.

doi:10.1107/S2414314618008921

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 3| Part 6| June 2018| x180892

https://doi.org/10.1107/S2414314618008921

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Ethyl 5-(4-methylphenyl)-2,4,5,7-tetraazatricyclo[6.4.0.0^2,6]dodeca-1(8),3,6,9,11-pentaene-3-carboxylate

Ahmed Moussaif,^a ^* Youssef Ramli,^b Lhoussaine El Ghayati,^c El Mokhtar Essassi ^c and Joel T. Mague ^d

^aNational Center of Energy Sciences and Nuclear Techniques, Rabat, Morocco, ^bLaboratory of Medicinal Chemistry, Faculty of Medicine and Pharmacy, Mohammed V University Rabat, Morocco, ^cLaboratoire de Chimie Organique Heterocyclique URAC 21, Av. Ibn Battouta, BP 1014, Faculté des Sciences, Université Mohammed V, Rabat, Morocco, and ^dDepartment of Chemistry, Tulane University, New Orleans, LA 70118, USA
^*Correspondence e-mail: ahmed_moussaif@yahoo.com

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 12 June 2018; accepted 18 June 2018; online 22 June 2018)

In the title compound, C₁₈H₁₆N₄O₂, the dihedral angle between the fused tricyclic ring system and the pendant benzene ring is 11.03 (4)°. The C—O—C—C torsion angle in the ethyl ester is 102.97 (12)°. The molecular conformation is supported by intramolecular C—H⋯N and C—H⋯O hydrogen bonds, which close S(6) and S(7) rings, respectively. Aromatic π–π stacking is observed in the crystal [shortest centroid–centroid separation = 3.5274 (7) Å].

Keywords: crystal structure; hydrogen bond; π-stacking; crystal structure.

CCDC reference: 1850161

Structure description

As a continuation of our research into benzimidazole derivatives (Moussaif et al. 2016 , El Bakri et al. 2018 ), the title compound (Fig. 1) was prepared and characterized by single-crystal X-ray diffraction.

Figure 1
The title molecule with 50% probability ellipsoids. The intramolecular hydrogen bonds are shown as dashed lines.

The fused tricyclic unit deviates slightly from planarity as indicated by the dihedral angle of 3.87 (6)° between the planes of the C1/C6/N1/C7/N4 and the C7/N2/N3/C8/N4 rings and by the dihedral angle of 2.05 (6)° between the planes of the C1/C6/N1/C7/N4 and the C1–C6 rings. The plane of the pendant C12–C17 ring is inclined to that of the C7/N2/N3/C8/N4 ring by 7.70 (5)°, which is likely due to the combination of the intramolecular C17—H17⋯N1 hydrogen bond (Table 1 and Fig. 2) and the π-stacking interactions between C7/N2/N3/C8/N4 and C12–C17 rings in inversion-related pairs of molecules [centroid–centroid separation = 3.5274 (7) Å, interplanar angle = 7.70 (5)°]. The orientation of the carboxyl group of the ester substituent is partially determined by the intramolecular C2—H2⋯O1 hydrogen bond.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯O1	0.941 (14)	2.498 (13)	3.1480 (14)	126.3 (11)
C17—H17⋯N1	0.956 (13)	2.490 (12)	3.1473 (14)	125.8 (10)

Figure 2
Packing viewed along the a-axis direction with π-stacking interactions shown as dashed lines.

Synthesis and crystallization

6 mmol of methylmercaptobenzimidazole was dissolved in 40 ml of THF and 8.1 mmol of diphenylnitrileimine and 8.1 mmol of TEA were added. The mixture was refluxed for 24 h using a chilled condenser and CaCl₂ trap to minimize water ingress. After cooling, the salts were removed by filtration and the solvent was evaporated under reduced pressure. Light-yellow blocks were obtained by recrystallization from ethanol solution.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₈H₁₆N₄O₂
M_r	320.35
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	9.2366 (11), 10.2045 (12), 16.1922 (18)
β (°)	92.144 (2)
V (Å³)	1525.1 (3)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.10
Crystal size (mm)	0.33 × 0.17 × 0.11

Data collection
Diffractometer	Bruker SMART APEX CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.88, 0.99
No. of measured, independent and observed [I > 2σ(I)] reflections	28729, 4119, 3269
R_int	0.034
(sin θ/λ)_max (Å⁻¹)	0.688

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.126, 1.10
No. of reflections	4119
No. of parameters	281
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.43, −0.19
Computer programs: APEX3 and SAINT (Bruker, 2016 ), SHELXT (Sheldrick, 2015a ), SHELXL2018 (Sheldrick, 2015b ), DIAMOND (Brandenburg & Putz, 2012 ) and SHELXTL (Sheldrick, 2008 ).

Structural data

CCDC reference: 1850161

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314618008921/hb4241sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618008921/hb4241Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314618008921/hb4241Isup3.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Ethyl 5-(4-methylphenyl)-2,4,5,7-tetraazatricyclo[6.4.0.0^2,6]dodeca-1(8),3,6,9,11-pentaene-3-carboxylate top

Crystal data top

C₁₈H₁₆N₄O₂	F(000) = 672
M_r = 320.35	D_x = 1.395 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 9.2366 (11) Å	Cell parameters from 9939 reflections
b = 10.2045 (12) Å	θ = 2.5–29.2°
c = 16.1922 (18) Å	µ = 0.10 mm⁻¹
β = 92.144 (2)°	T = 100 K
V = 1525.1 (3) Å³	Column, light yellow
Z = 4	0.33 × 0.17 × 0.11 mm

Data collection top

Bruker SMART APEX CCD diffractometer	4119 independent reflections
Radiation source: fine-focus sealed tube	3269 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.034
Detector resolution: 8.3333 pixels mm^-1	θ_max = 29.3°, θ_min = 2.4°
φ and ω scans	h = −12→12
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	k = −13→14
T_min = 0.88, T_max = 0.99	l = −22→21
28729 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.044	Hydrogen site location: difference Fourier map
wR(F²) = 0.126	All H-atom parameters refined
S = 1.10	w = 1/[σ²(F_o²) + (0.0837P)²] where P = (F_o² + 2F_c²)/3
4119 reflections	(Δ/σ)_max < 0.001
281 parameters	Δρ_max = 0.43 e Å⁻³
0 restraints	Δρ_min = −0.19 e Å⁻³

Special details top

Experimental. The diffraction data were obtained from 3 sets of 400 frames, each of width 0.5° in ω, colllected at φ = 0.00, 90.00 and 180.00° and 2 sets of 800 frames, each of width 0.45° in φ, collected at ω = –30.00 and 210.00°. The scan time was 20 sec/frame.

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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	U_iso*/U_eq
O1	0.27907 (9)	0.03912 (8)	0.51898 (5)	0.0305 (2)
O2	0.22672 (9)	0.16022 (8)	0.40455 (5)	0.0291 (2)
N1	0.73373 (10)	0.31219 (9)	0.59612 (5)	0.0225 (2)
N2	0.59679 (9)	0.35622 (8)	0.46266 (5)	0.0204 (2)
N3	0.47218 (10)	0.30038 (8)	0.42909 (5)	0.0214 (2)
N4	0.53322 (10)	0.20134 (8)	0.54708 (5)	0.0198 (2)
C1	0.56736 (11)	0.14534 (10)	0.62432 (6)	0.0207 (2)
C2	0.50476 (12)	0.04636 (10)	0.66949 (6)	0.0232 (2)
H2	0.4245 (16)	−0.0026 (14)	0.6496 (8)	0.033 (3)*
C3	0.56831 (12)	0.02072 (11)	0.74701 (7)	0.0260 (2)
H3	0.5272 (15)	−0.0462 (12)	0.7811 (8)	0.029 (3)*
C4	0.68767 (12)	0.09204 (11)	0.77778 (7)	0.0262 (2)
H4	0.7286 (15)	0.0763 (13)	0.8336 (8)	0.031 (3)*
C5	0.75050 (12)	0.19019 (11)	0.73189 (7)	0.0246 (2)
H5	0.8333 (16)	0.2357 (12)	0.7552 (8)	0.035 (4)*
C6	0.69074 (11)	0.21704 (10)	0.65324 (6)	0.0212 (2)
C7	0.63534 (11)	0.29777 (10)	0.53647 (6)	0.0201 (2)
C8	0.43553 (12)	0.20874 (10)	0.48072 (6)	0.0209 (2)
C9	0.30540 (12)	0.12523 (10)	0.47099 (6)	0.0231 (2)
C10	0.09331 (13)	0.08760 (12)	0.38572 (8)	0.0315 (3)
H10A	0.0950 (14)	0.0742 (12)	0.3234 (8)	0.029 (3)*
H10B	0.1026 (15)	−0.0018 (15)	0.4127 (8)	0.041 (4)*
C11	−0.03431 (15)	0.16685 (15)	0.41023 (9)	0.0382 (3)
H11A	−0.0357 (17)	0.1755 (15)	0.4712 (10)	0.049 (4)*
H11B	−0.1280 (16)	0.1198 (14)	0.3897 (8)	0.041 (4)*
H11C	−0.0356 (17)	0.2555 (15)	0.3833 (9)	0.044 (4)*
C12	0.66049 (11)	0.46589 (9)	0.42400 (6)	0.0192 (2)
C13	0.58932 (11)	0.52255 (10)	0.35533 (6)	0.0215 (2)
H13	0.4937 (14)	0.4852 (12)	0.3339 (7)	0.027 (3)*
C14	0.65297 (12)	0.62930 (10)	0.31773 (6)	0.0233 (2)
H14	0.5988 (14)	0.6704 (13)	0.2681 (8)	0.034 (3)*
C15	0.78523 (12)	0.68054 (10)	0.34691 (6)	0.0229 (2)
C16	0.85299 (12)	0.62162 (11)	0.41557 (7)	0.0248 (2)
H16	0.9471 (16)	0.6601 (13)	0.4358 (9)	0.038 (4)*
C17	0.79222 (12)	0.51494 (11)	0.45474 (7)	0.0233 (2)
H17	0.8409 (14)	0.4748 (12)	0.5014 (8)	0.024 (3)*
C18	0.85216 (15)	0.79542 (12)	0.30434 (9)	0.0329 (3)
H18A	0.881 (2)	0.7749 (17)	0.2454 (12)	0.078 (6)*
H18B	0.9384 (18)	0.8226 (15)	0.3336 (9)	0.049 (4)*
H18C	0.786 (2)	0.870 (2)	0.2983 (12)	0.082 (6)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0370 (5)	0.0272 (4)	0.0273 (4)	−0.0104 (3)	−0.0013 (3)	0.0036 (3)
O2	0.0304 (4)	0.0284 (4)	0.0279 (4)	−0.0084 (3)	−0.0064 (3)	0.0036 (3)
N1	0.0221 (5)	0.0253 (5)	0.0199 (4)	−0.0003 (4)	−0.0001 (3)	0.0028 (3)
N2	0.0214 (4)	0.0208 (4)	0.0188 (4)	−0.0022 (3)	−0.0002 (3)	0.0005 (3)
N3	0.0227 (4)	0.0208 (4)	0.0205 (4)	−0.0029 (3)	−0.0003 (3)	−0.0018 (3)
N4	0.0227 (4)	0.0184 (4)	0.0183 (4)	0.0001 (3)	0.0007 (3)	0.0005 (3)
C1	0.0231 (5)	0.0208 (5)	0.0185 (5)	0.0036 (4)	0.0016 (4)	0.0002 (4)
C2	0.0238 (5)	0.0207 (5)	0.0253 (5)	0.0010 (4)	0.0031 (4)	0.0007 (4)
C3	0.0295 (6)	0.0242 (5)	0.0246 (5)	0.0033 (4)	0.0064 (4)	0.0051 (4)
C4	0.0279 (6)	0.0298 (6)	0.0211 (5)	0.0059 (4)	0.0025 (4)	0.0038 (4)
C5	0.0225 (5)	0.0279 (6)	0.0233 (5)	0.0025 (4)	0.0010 (4)	0.0008 (4)
C6	0.0213 (5)	0.0209 (5)	0.0214 (5)	0.0018 (4)	0.0039 (4)	0.0011 (4)
C7	0.0209 (5)	0.0205 (5)	0.0191 (5)	0.0003 (4)	0.0027 (4)	−0.0001 (4)
C8	0.0244 (5)	0.0185 (5)	0.0200 (5)	−0.0005 (4)	0.0014 (4)	−0.0020 (4)
C9	0.0263 (5)	0.0204 (5)	0.0226 (5)	−0.0029 (4)	0.0010 (4)	−0.0032 (4)
C10	0.0337 (6)	0.0284 (6)	0.0317 (6)	−0.0108 (5)	−0.0083 (5)	−0.0022 (5)
C11	0.0339 (7)	0.0448 (8)	0.0365 (7)	−0.0162 (6)	0.0078 (5)	−0.0090 (6)
C12	0.0213 (5)	0.0176 (5)	0.0189 (4)	0.0003 (4)	0.0039 (4)	−0.0011 (4)
C13	0.0226 (5)	0.0207 (5)	0.0211 (5)	−0.0010 (4)	0.0018 (4)	−0.0007 (4)
C14	0.0262 (5)	0.0214 (5)	0.0223 (5)	0.0020 (4)	0.0031 (4)	0.0019 (4)
C15	0.0238 (5)	0.0188 (5)	0.0265 (5)	0.0008 (4)	0.0071 (4)	−0.0009 (4)
C16	0.0214 (5)	0.0245 (5)	0.0285 (5)	−0.0017 (4)	0.0023 (4)	−0.0016 (4)
C17	0.0231 (5)	0.0234 (5)	0.0232 (5)	0.0000 (4)	−0.0001 (4)	0.0010 (4)
C18	0.0297 (6)	0.0251 (6)	0.0447 (7)	−0.0028 (5)	0.0096 (5)	0.0079 (5)

Geometric parameters (Å, º) top

O1—C9	1.2038 (13)	C8—C9	1.4770 (15)
O2—C9	1.3246 (13)	C10—C11	1.4953 (19)
O2—C10	1.4603 (13)	C10—H10A	1.019 (13)
N1—C7	1.3094 (13)	C10—H10B	1.014 (15)
N1—C6	1.4083 (13)	C11—H11A	0.992 (16)
N2—C7	1.3709 (12)	C11—H11B	1.034 (15)
N2—N3	1.3777 (12)	C11—H11C	1.004 (15)
N2—C12	1.4207 (13)	C12—C17	1.3905 (15)
N3—C8	1.3072 (13)	C12—C13	1.3957 (14)
N4—C7	1.3783 (14)	C13—C14	1.3891 (14)
N4—C8	1.3791 (13)	C13—H13	1.011 (13)
N4—C1	1.4002 (12)	C14—C15	1.3950 (15)
C1—C2	1.3860 (14)	C14—H14	1.020 (13)
C1—C6	1.4190 (14)	C15—C16	1.3918 (15)
C2—C3	1.3905 (15)	C15—C18	1.5045 (15)
C2—H2	0.941 (14)	C16—C17	1.3889 (15)
C3—C4	1.3973 (17)	C16—H16	0.999 (14)
C3—H3	0.965 (12)	C17—H17	0.956 (13)
C4—C5	1.3872 (16)	C18—H18A	1.021 (19)
C4—H4	0.980 (14)	C18—H18B	0.952 (17)
C5—C6	1.3961 (14)	C18—H18C	0.98 (2)
C5—H5	0.960 (15)

C9—O2—C10	117.77 (9)	O2—C10—C11	109.73 (10)
C7—N1—C6	101.65 (9)	O2—C10—H10A	103.4 (7)
C7—N2—N3	110.48 (8)	C11—C10—H10A	112.1 (7)
C7—N2—C12	128.95 (8)	O2—C10—H10B	108.0 (8)
N3—N2—C12	120.37 (8)	C11—C10—H10B	115.3 (8)
C8—N3—N2	106.03 (8)	H10A—C10—H10B	107.5 (11)
C7—N4—C8	107.14 (8)	C10—C11—H11A	110.6 (9)
C7—N4—C1	105.68 (9)	C10—C11—H11B	108.8 (8)
C8—N4—C1	146.85 (9)	H11A—C11—H11B	108.6 (12)
C2—C1—N4	133.18 (10)	C10—C11—H11C	111.6 (9)
C2—C1—C6	123.18 (9)	H11A—C11—H11C	110.6 (12)
N4—C1—C6	103.63 (9)	H11B—C11—H11C	106.4 (12)
C1—C2—C3	116.31 (10)	C17—C12—C13	121.06 (9)
C1—C2—H2	123.0 (8)	C17—C12—N2	119.81 (9)
C3—C2—H2	120.7 (8)	C13—C12—N2	119.14 (9)
C2—C3—C4	121.64 (10)	C14—C13—C12	118.66 (10)
C2—C3—H3	119.2 (8)	C14—C13—H13	121.6 (7)
C4—C3—H3	119.1 (8)	C12—C13—H13	119.7 (7)
C5—C4—C3	121.70 (10)	C13—C14—C15	121.67 (10)
C5—C4—H4	117.3 (8)	C13—C14—H14	117.6 (8)
C3—C4—H4	121.0 (8)	C15—C14—H14	120.7 (8)
C4—C5—C6	118.12 (10)	C16—C15—C14	118.07 (10)
C4—C5—H5	118.8 (8)	C16—C15—C18	121.49 (10)
C6—C5—H5	123.1 (8)	C14—C15—C18	120.43 (10)
C5—C6—N1	128.52 (10)	C17—C16—C15	121.74 (10)
C5—C6—C1	119.02 (10)	C17—C16—H16	121.4 (8)
N1—C6—C1	112.43 (9)	C15—C16—H16	116.9 (8)
N1—C7—N2	138.13 (10)	C16—C17—C12	118.80 (10)
N1—C7—N4	116.59 (9)	C16—C17—H17	120.7 (8)
N2—C7—N4	105.22 (9)	C12—C17—H17	120.5 (8)
N3—C8—N4	111.10 (9)	C15—C18—H18A	113.1 (10)
N3—C8—C9	125.01 (9)	C15—C18—H18B	110.4 (9)
N4—C8—C9	123.88 (9)	H18A—C18—H18B	106.6 (14)
O1—C9—O2	127.09 (10)	C15—C18—H18C	112.8 (12)
O1—C9—C8	122.38 (10)	H18A—C18—H18C	104.3 (15)
O2—C9—C8	110.53 (9)	H18B—C18—H18C	109.3 (14)

C7—N2—N3—C8	−0.56 (11)	C1—N4—C7—N2	−177.11 (8)
C12—N2—N3—C8	−175.94 (8)	N2—N3—C8—N4	−0.66 (12)
C7—N4—C1—C2	179.09 (11)	N2—N3—C8—C9	178.15 (9)
C8—N4—C1—C2	7.4 (2)	C7—N4—C8—N3	1.62 (12)
C7—N4—C1—C6	0.22 (10)	C1—N4—C8—N3	173.26 (13)
C8—N4—C1—C6	−171.48 (14)	C7—N4—C8—C9	−177.21 (9)
N4—C1—C2—C3	−177.77 (10)	C1—N4—C8—C9	−5.6 (2)
C6—C1—C2—C3	0.92 (15)	C10—O2—C9—O1	−0.36 (17)
C1—C2—C3—C4	0.69 (16)	C10—O2—C9—C8	−179.86 (9)
C2—C3—C4—C5	−1.30 (17)	N3—C8—C9—O1	177.45 (10)
C3—C4—C5—C6	0.26 (16)	N4—C8—C9—O1	−3.88 (17)
C4—C5—C6—N1	179.03 (10)	N3—C8—C9—O2	−3.03 (15)
C4—C5—C6—C1	1.28 (15)	N4—C8—C9—O2	175.64 (10)
C7—N1—C6—C5	−176.48 (11)	C9—O2—C10—C11	102.97 (12)
C7—N1—C6—C1	1.39 (11)	C7—N2—C12—C17	10.61 (16)
C2—C1—C6—C5	−1.94 (16)	N3—N2—C12—C17	−174.96 (9)
N4—C1—C6—C5	177.08 (9)	C7—N2—C12—C13	−169.52 (9)
C2—C1—C6—N1	179.97 (9)	N3—N2—C12—C13	4.91 (14)
N4—C1—C6—N1	−1.02 (11)	C17—C12—C13—C14	0.22 (15)
C6—N1—C7—N2	175.57 (12)	N2—C12—C13—C14	−179.65 (9)
C6—N1—C7—N4	−1.28 (12)	C12—C13—C14—C15	−0.02 (16)
N3—N2—C7—N1	−175.57 (12)	C13—C14—C15—C16	−0.06 (16)
C12—N2—C7—N1	−0.7 (2)	C13—C14—C15—C18	179.39 (10)
N3—N2—C7—N4	1.52 (11)	C14—C15—C16—C17	−0.07 (16)
C12—N2—C7—N4	176.39 (9)	C18—C15—C16—C17	−179.52 (11)
C8—N4—C7—N1	175.98 (9)	C15—C16—C17—C12	0.28 (16)
C1—N4—C7—N1	0.72 (12)	C13—C12—C17—C16	−0.35 (16)
C8—N4—C7—N2	−1.85 (11)	N2—C12—C17—C16	179.52 (9)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O1	0.941 (14)	2.498 (13)	3.1480 (14)	126.3 (11)
C17—H17···N1	0.956 (13)	2.490 (12)	3.1473 (14)	125.8 (10)

Funding information

JTM thanks Tulane University for support of the Tulane Crystallography Laboratory.

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