Crystal structures of 2-(benzene-carbo-thio-yloxy)ethyl benzene-carbo-thio-ate and 2-(benzene-carbo-thio-yloxy)ethyl benzoate.

The title compounds, C16H14O2S2 and C16H14O3S, which are monomeric models (models D and E) for a polythio-noester and a poly(ester-co-thio-noester), respectively, crystallize in the space group P21/c and are isostructural with each other. The mol-ecule in each crystal is located on an inversion centre and has an all-trans structure. The asymmetric unit comprises one half-mol-ecule. In the crystal, there are inter-molecular C⋯S contacts [3.391 (3) and 3.308 (3) Å for models D and E, respectively] and C-H⋯π inter-actions, which form a layer structure parallel to the bc plane. The carbonyl and thio-carbonyl groups of the model E compound are each disordered over two equivalent sites about the inversion centre with equal occupancies.

Chemical context

Compounds expressed as C6H5—C(=X)—Y—CH2—CH2—Y—C(=X)—C6H5 (X, Y = O or S) can be considered to be monomeric models for polymers, [—C(=X)—C6H4—C(=X)—Y—CH2—CH2—Y—], namely, X = Y = O, poly(ethyl­ene terephthalate) (designated herein as polymer A); X = O and Y = S, poly(ethyl­ene di­thio­terephthalate) (polymer B); X = Y = S, poly(ethyl­ene tetra­thio­terephthalate) (polymer C); X = S and Y = O, poly(ethyl­ene di­thio­noterephthalate) (polymer D). It is well established that the solution, mechanical and thermal properties of such aromatic polymers are essentially determined by the conformational characteristics of the Y—CH2—CH2—Y unit (referred hereafter to as the spacer) and inter­molecular inter­actions between the benzene rings (Sasanuma, 2009 ▸; Sasanuma et al., 2013 ▸). In expectation that replacement of oxygen by sulfur at the X or Y site would affect the spacer conformation, and π–π and C—H⋯π inter­actions of the benzene rings, and thus lead to variations in the physical properties, we synthesized polymers B and C, and characterized them by X-ray diffraction, NMR spectroscopy, thermal analyses, mol­ecular orbital calculations and statistical mechanics of the chain mol­ecules (Abe & Sasanuma, 2012 ▸). Herein, the monomeric models for polymers A–D are termed models A–D, respectively.

By mol­ecular orbital calculations at the second-order Møller–Plesset perturbation (MP2) level with moderate-size basis sets, we have determined the most stable conformations of the Y—CH2—CH2—Y parts of the models and evaluated their free energies relative to that of the all-trans form as follows: model A, tgt and −1.1 kcal mol−1 (Sasanuma, 2009 ▸); model B, g±tg∓ and −3.1 kcal mol−1 (Abe & Sasanuma, 2012 ▸); model C, g±tg∓ and −2.1 kcal mol−1 (Abe & Sasanuma, 2012 ▸); model D, tgt and −1.7 kcal mol−1 (this study). We have also predicted that an asymmetric model compound, C6H5—C(=O)—O—CH2—CH2—O—C(=S)—C6H5 (model E), would be most stabilized in the tg±g∓ conformation with a free energy of −1.8 kcal mol−1 (this study). However, not all the models and polymers crystallize in the lowest-energy conformations: model (polymer) A, ttt (ttt) (Pérez & Brisse, 1976 ▸; Daubeny et al., 1954 ▸); model (polymer) B, g±tg∓ (g±tg∓) (Deguire & Brisse, 1988 ▸; Abe & Sasanuma, 2012 ▸); model (polymer) C, g±tg∓ (amorphous) (Abe et al., 2011 ▸; Abe & Sasanuma, 2012 ▸). In the crystals, the mol­ecules adopt conformations so as to form inter­molecular inter­actions effectively and minimize the total of intra­molecular and inter­molecular inter­action energies. Inter­estingly, however, models A–C crystallize in the same spacer conformation as those of the corresponding polymers; therefore, the crystal structure of the model suggests the polymer conformation. This study has aimed to determine crystal structures of the title compounds (models D and E) to predict the crystal conformations of polymers D and E on the above hypothesis.

Structural commentary

The mol­ecule of model D lies on an inversion centre and the asymmetric unit contains one half-mol­ecule. The central O—CH2—CH2—O unit adopts an all-trans conformation (Fig. 1 ▸). The mol­ecule of model E is also located on an inversion centre and the O—CH2—CH2—O bond sequence is in an all-trans conformation. Since the mol­ecule has carbonyl and thio­carbonyl groups, the atoms S and O (S1 and O2) are each assumed to be disordered over two equivalent sites about the inversion centre with equal occupancies (Fig. 2 ▸). Consequently, it was proved that all the models (A, D and E) with the O—CH2—CH2—O spacer crystallize with all-trans structures, although models A, D and E in the free state are most stabilized in tgt, tgt, and tg±g∓ conformations, respectively.

Figure 1

The mol­ecular structure of model D, showing atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. The unlabelled atoms are related to the labelled atoms by inversion symmetry (symmetry code: 2 − x, 2 − y, 2 − z,). H atoms are represented by spheres of arbitrary size.

Figure 2

The mol­ecular structure of model E, showing atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. The unlabelled atoms are related to the labelled atoms by inversion symmetry (symmetry code: 2 − x, 2 − y, 2 − z,). H atoms are represented by spheres of arbitrary size.

Supra­molecular features

The compounds of models D and E are isotypic and crystallize in the space group P21/c. There are no classical hydrogen bonds but inter­molecular close contacts between atoms C and S [C1—S1i = 3.391 (3) and 3.308 (3) Å for models D and E, respectively; symmetry code: (i) x, –y + , z – ]. Both compounds also have C—H⋯π inter­actions (Tables 1 ▸ and 2 ▸) and form layer structures parallel to the bc plane via these inter­molecular inter­actions (Figs. 3 ▸ and 4 ▸).

Table 1

C—H⋯π inter­action geometry (Å, °) for model D

Cg1 is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯Cg1i	0.95	2.92	3.721 (3)	143

Symmetry code: (i) x, −y + , z − .

Table 2

C—H⋯π inter­action geometry (Å, °) for model E

Cg1 is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯Cg1i	0.95	2.89	3.641 (3)	137

Symmetry code: (i) x, −y + , z − .

Figure 3

A packing diagram of model D, showing inter­molecular C⋯S contacts (red dotted lines) and C—H⋯π inter­actions (blue dotted lines).

Figure 4

A packing diagram of model E, showing inter­molecular C⋯S contacts (red dotted lines) and C—H⋯π inter­actions (blue dotted lines).

Synthesis and crystallization

Benzoyl chloride (10.0 ml, 87 mmol) was added dropwise under a nitro­gen atmosphere to ethyl­ene glycol (2.4 ml, 43 mmol) and pyridine (7.0 ml, 87 mmol) placed in a four-necked flask connected to a drying tube filled with calcium chloride, and the mixture was stirred at room temperature overnight. Water was added to the reaction mixture to yield a precipitate, which was collected by filtration, dissolved in chloro­form, washed thrice with 5% aqueous solution of sodium bicarbonate, and dried over anhydrous magnesium sulfate overnight. The liquid phase was separated by filtration and condensed on a rotary evaporator, and the residue was recrystallized from ethanol (15 ml). The white crystallites thus obtained were dried under reduced pressure at room temperature overnight to yield ethane-1,2-diyl dibenzoate (8.3 g, 71%). The synthesized ethane-1,2-diyl dibenzoate (0.10 g, 0.37 mmol) was ground in a mortar and mixed thoroughly with Lawesson’s reagent (0.24 g, 0.59 mmol), and the powder mixture was moved to a 15 ml vial container and placed in a Yuasa PRE-7017R microwave oven. The powder was heated under the following microwave irradiation at 500 W: on for 2.0 min – off for several seconds – on for 1.0 min. The above handling was repeated ten times to obtain the product sufficiently.

The crude product was extracted with chloro­form and condensed under reduced pressure. The residue was dissolved in a mixed solvent of ethyl acetate and n-hexane (1:9 v/v) and subjected to column chromatography. The yellowish fraction (R f = 0.5) was collected and condensed, and the residue underwent column chromatography again with a mixed solvent of toluene and n-hexane (1:5 v/v). Two yellow fractions [(1) R f = 0.1 and (2) 0.3 − 0.5] were stratified and collected separately. The layer (1) was condensed and recrystallized from ethanol to yield a yellow solid, which was identified as 2-(benzene­carbo­thio­yloxy)ethyl benzoate (model E, yield 23%) by 1H and 13C NMR, and the layer (2) was condensed and dried at room temperature overnight to yield a red solid, which was identified as 2-(benzene­carbo­thio­yloxy)ethyl benzene­carbo­thio­ate (model D, yield 0.9%). A small qu­antity of model D was dissolved in chloro­form in a thin vial container. The vessel was placed in a larger vial containing a small amount of n-hexane, and the outer container was capped. After a week, single crystals were found to be formed in the inner vessel. Single crystals of model E were prepared similarly.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. All H atoms were geometrically positioned with C—H = 0.95 and 0.99 Å for the aromatic and methyl­ene groups, respectively, and were refined as riding with U iso(H) = 1.2 U eq(C).

Table 3

Experimental details

	model D	model E
Crystal data
Chemical formula	C16H14O2S2	C16H14O3S
M r	302.39	286.33
Crystal system, space group	Monoclinic, P21/c	Monoclinic, P21/c
Temperature (K)	173	173
a, b, c (Å)	8.829 (5), 11.680 (7), 7.727 (5)	8.800 (5), 11.403 (6), 7.506 (4)
β (°)	113.475 (10)	113.831 (6)
V (Å3)	730.9 (8)	689.0 (6)
Z	2	2
Radiation type	Mo Kα	Mo Kα
μ (mm−1)	0.36	0.24
Crystal size (mm)	0.40 × 0.40 × 0.20	0.40 × 0.40 × 0.10
Data collection
Diffractometer	Bruker APEXII CCD area detector	Bruker APEXII CCD area detector
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996 ▸)	Multi-scan (SADABS; Sheldrick, 1996 ▸)
T min, T max	0.88, 0.93	0.84, 0.98
No. of measured, independent and observed [I > 2σ(I)] reflections	4017, 1617, 1487	3265, 1523, 1335
R int	0.014	0.015
(sin θ/λ)max (Å−1)	0.648	0.653
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.029, 0.080, 1.03	0.038, 0.090, 1.08
No. of reflections	1617	1523
No. of parameters	91	100
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.39, −0.20	0.19, −0.16

Computer programs: APEX2, SAINT, XSHEL and XCIF (Bruker, 2012 ▸) SHELXS97 (Sheldrick, 2008 ▸) and SHELXL2013 (Sheldrick, 2015 ▸).

Crystal structure: contains datablock(s) General, model_D, model_E. DOI: 10.1107/S2056989017012701/is5479sup1.cif

Structure factors: contains datablock(s) model_D. DOI: 10.1107/S2056989017012701/is5479model_Dsup4.hkl

Structure factors: contains datablock(s) model_E. DOI: 10.1107/S2056989017012701/is5479model_Esup5.hkl

CCDC references: 1572676, 1572675

Additional supporting information: crystallographic information; 3D view; checkCIF report

C16H14O2S2	F(000) = 316
Mr = 302.39	Dx = 1.374 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.829 (5) Å	Cell parameters from 2339 reflections
b = 11.680 (7) Å	θ = 2.5–27.6°
c = 7.727 (5) Å	µ = 0.36 mm−1
β = 113.475 (10)°	T = 173 K
V = 730.9 (8) Å3	Prismatic, yellow
Z = 2	0.40 × 0.40 × 0.20 mm

Bruker APEXII CCD area detector diffractometer	1617 independent reflections
Radiation source: fine-focus sealed tube	1487 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.014
Detector resolution: 8.3333 pixels mm-1	θmax = 27.4°, θmin = 2.5°
φ and ω scans	h = −10→11
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −13→15
Tmin = 0.88, Tmax = 0.93	l = −9→5
4017 measured reflections

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.029	H-atom parameters constrained
wR(F2) = 0.080	w = 1/[σ2(Fo2) + (0.0425P)2 + 0.2706P] where P = (Fo2 + 2Fc2)/3
S = 1.03	(Δ/σ)max = 0.001
1617 reflections	Δρmax = 0.39 e Å−3
91 parameters	Δρmin = −0.20 e Å−3

Experimental. SADABS (Sheldrick 1996)

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.

	x	y	z	Uiso*/Ueq
C1	0.70662 (15)	0.86862 (11)	0.98706 (17)	0.0209 (3)
C2	0.52641 (15)	0.87852 (10)	0.86705 (17)	0.0205 (3)
C3	0.41444 (16)	0.80285 (12)	0.89460 (19)	0.0271 (3)
H3	0.4532	0.7468	0.9916	0.033*
C4	0.24591 (17)	0.80973 (13)	0.7796 (2)	0.0312 (3)
H4	0.1705	0.7586	0.7991	0.037*
C5	0.18837 (16)	0.89124 (13)	0.6367 (2)	0.0309 (3)
H5	0.0741	0.8947	0.5572	0.037*
C6	0.29824 (17)	0.96779 (13)	0.6101 (2)	0.0316 (3)
H6	0.2585	1.024	0.5136	0.038*
C7	0.46690 (16)	0.96209 (11)	0.72503 (19)	0.0259 (3)
H7	0.5413	1.0148	0.707	0.031*
C8	0.97120 (15)	0.94978 (12)	1.04144 (19)	0.0267 (3)
H8A	1.0184	0.8771	1.0194	0.032*
H8B	1.0041	0.9599	1.1788	0.032*
O1	0.79324 (11)	0.95006 (8)	0.94319 (13)	0.0252 (2)
S1	0.79118 (4)	0.77062 (3)	1.15081 (5)	0.02945 (13)

	U11	U22	U33	U12	U13	U23
C1	0.0204 (6)	0.0227 (6)	0.0205 (6)	−0.0032 (5)	0.0091 (5)	−0.0036 (5)
C2	0.0189 (6)	0.0224 (6)	0.0205 (6)	−0.0013 (5)	0.0080 (5)	−0.0036 (5)
C3	0.0232 (6)	0.0300 (7)	0.0265 (7)	−0.0040 (5)	0.0081 (5)	0.0023 (5)
C4	0.0221 (6)	0.0373 (8)	0.0334 (7)	−0.0072 (6)	0.0103 (6)	−0.0024 (6)
C5	0.0191 (6)	0.0376 (8)	0.0318 (7)	0.0020 (5)	0.0057 (5)	−0.0050 (6)
C6	0.0274 (7)	0.0315 (7)	0.0314 (7)	0.0051 (6)	0.0068 (6)	0.0049 (6)
C7	0.0244 (7)	0.0244 (6)	0.0283 (7)	−0.0010 (5)	0.0099 (5)	0.0014 (5)
C8	0.0170 (6)	0.0314 (7)	0.0281 (6)	−0.0041 (5)	0.0051 (5)	0.0030 (5)
O1	0.0174 (4)	0.0269 (5)	0.0282 (5)	−0.0042 (3)	0.0057 (4)	0.0037 (4)
S1	0.02236 (19)	0.0332 (2)	0.0302 (2)	−0.00007 (13)	0.00763 (14)	0.00936 (13)

C1—O1	1.3458 (16)	C5—C6	1.393 (2)
C1—C2	1.4931 (18)	C5—H5	0.95
C1—S1	1.6481 (14)	C6—C7	1.399 (2)
C2—C3	1.4042 (19)	C6—H6	0.95
C2—C7	1.4049 (19)	C7—H7	0.95
C3—C4	1.399 (2)	C8—O1	1.4474 (17)
C3—H3	0.95	C8—C8i	1.518 (3)
C4—C5	1.392 (2)	C8—H8A	0.99
C4—H4	0.95	C8—H8B	0.99
O1—C1—C2	111.15 (11)	C6—C5—H5	120.0
O1—C1—S1	123.72 (10)	C5—C6—C7	120.22 (13)
C2—C1—S1	125.13 (9)	C5—C6—H6	119.9
C3—C2—C7	119.27 (12)	C7—C6—H6	119.9
C3—C2—C1	119.84 (12)	C6—C7—C2	120.09 (12)
C7—C2—C1	120.89 (11)	C6—C7—H7	120.0
C4—C3—C2	120.17 (13)	C2—C7—H7	120.0
C4—C3—H3	119.9	O1—C8—C8i	104.66 (13)
C2—C3—H3	119.9	O1—C8—H8A	110.8
C5—C4—C3	120.21 (13)	C8i—C8—H8A	110.8
C5—C4—H4	119.9	O1—C8—H8B	110.8
C3—C4—H4	119.9	C8i—C8—H8B	110.8
C4—C5—C6	120.02 (13)	H8A—C8—H8B	108.9
C4—C5—H5	120.0	C1—O1—C8	118.26 (10)

C16H14O3S	F(000) = 300
Mr = 286.33	Dx = 1.380 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.800 (5) Å	Cell parameters from 1991 reflections
b = 11.403 (6) Å	θ = 2.5–27.6°
c = 7.506 (4) Å	µ = 0.24 mm−1
β = 113.831 (6)°	T = 173 K
V = 689.0 (6) Å3	Prismatic, yellow
Z = 2	0.40 × 0.40 × 0.10 mm

Bruker APEXII CCD area detector diffractometer	1523 independent reflections
Radiation source: fine-focus sealed tube	1335 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
Detector resolution: 8.3333 pixels mm-1	θmax = 27.7°, θmin = 2.5°
φ and ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −6→14
Tmin = 0.84, Tmax = 0.98	l = −8→9
3265 measured reflections

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.038	H-atom parameters constrained
wR(F2) = 0.090	w = 1/[σ2(Fo2) + (0.0288P)2 + 0.2342P] where P = (Fo2 + 2Fc2)/3
S = 1.08	(Δ/σ)max = 0.002
1523 reflections	Δρmax = 0.19 e Å−3
100 parameters	Δρmin = −0.16 e Å−3

Experimental. SADABS (Sheldrick 1996)

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.

	x	y	z	Uiso*/Ueq	Occ. (<1)
S1	0.78695 (19)	0.76827 (18)	1.1323 (3)	0.0410 (3)	0.5
O2	0.7837 (8)	0.7828 (6)	1.0959 (10)	0.087 (3)	0.5
O1	0.79258 (12)	0.94978 (9)	0.93503 (15)	0.0404 (3)
C1	0.70747 (18)	0.86474 (13)	0.9769 (2)	0.0372 (3)
C2	0.52662 (17)	0.87657 (12)	0.86227 (19)	0.0338 (3)
C3	0.4186 (2)	0.79742 (14)	0.8908 (2)	0.0428 (4)
H3	0.461	0.7372	0.9857	0.051*
C4	0.2497 (2)	0.80604 (15)	0.7815 (2)	0.0486 (4)
H4	0.1762	0.7516	0.8014	0.058*
C5	0.1873 (2)	0.89288 (16)	0.6442 (3)	0.0492 (4)
H5	0.0711	0.8978	0.5681	0.059*
C6	0.2934 (2)	0.97304 (15)	0.6168 (2)	0.0470 (4)
H6	0.2498	1.0336	0.5229	0.056*
C7	0.46254 (18)	0.96570 (12)	0.7252 (2)	0.0381 (3)
H7	0.5351	1.0213	0.7064	0.046*
C8	0.97020 (18)	0.94635 (14)	1.0342 (2)	0.0440 (4)
H8A	1.0153	0.8744	0.9999	0.053*
H8B	1.0047	0.9485	1.1771	0.053*

	U11	U22	U33	U12	U13	U23
S1	0.0345 (5)	0.0398 (5)	0.0452 (6)	0.0040 (4)	0.0125 (4)	0.0086 (5)
O2	0.094 (4)	0.073 (4)	0.086 (5)	−0.007 (3)	0.028 (3)	0.007 (3)
O1	0.0368 (5)	0.0394 (6)	0.0392 (6)	−0.0059 (4)	0.0093 (4)	0.0043 (4)
C1	0.0457 (8)	0.0330 (7)	0.0324 (8)	−0.0042 (6)	0.0153 (6)	−0.0013 (6)
C2	0.0419 (8)	0.0332 (7)	0.0270 (7)	−0.0048 (6)	0.0144 (6)	−0.0058 (5)
C3	0.0536 (9)	0.0417 (8)	0.0333 (8)	−0.0113 (7)	0.0176 (7)	−0.0028 (6)
C4	0.0475 (9)	0.0563 (10)	0.0462 (10)	−0.0191 (8)	0.0233 (7)	−0.0124 (8)
C5	0.0380 (8)	0.0592 (10)	0.0489 (10)	−0.0037 (7)	0.0159 (7)	−0.0100 (8)
C6	0.0445 (8)	0.0470 (9)	0.0464 (10)	0.0036 (7)	0.0151 (7)	0.0021 (7)
C7	0.0427 (8)	0.0343 (7)	0.0380 (8)	−0.0027 (6)	0.0171 (6)	−0.0010 (6)
C8	0.0365 (8)	0.0462 (9)	0.0437 (9)	−0.0044 (7)	0.0103 (6)	0.0033 (7)

S1—C1	1.549 (3)	C4—H4	0.95
O2—C1	1.279 (6)	C5—C6	1.380 (2)
O1—C1	1.3381 (18)	C5—H5	0.95
O1—C8	1.4349 (19)	C6—C7	1.380 (2)
C1—C2	1.478 (2)	C6—H6	0.95
C2—C3	1.389 (2)	C7—H7	0.95
C2—C7	1.393 (2)	C8—C8i	1.501 (3)
C3—C4	1.381 (2)	C8—H8A	0.99
C3—H3	0.95	C8—H8B	0.99
C4—C5	1.374 (3)
C1—O1—C8	117.01 (12)	C4—C5—C6	119.98 (15)
O2—C1—O1	120.5 (3)	C4—C5—H5	120.0
O2—C1—C2	127.6 (3)	C6—C5—H5	120.0
O1—C1—C2	111.73 (13)	C5—C6—C7	120.36 (16)
O1—C1—S1	124.48 (13)	C5—C6—H6	119.8
C2—C1—S1	123.75 (13)	C7—C6—H6	119.8
C3—C2—C7	119.33 (14)	C6—C7—C2	119.85 (14)
C3—C2—C1	119.61 (14)	C6—C7—H7	120.1
C7—C2—C1	121.06 (13)	C2—C7—H7	120.1
C4—C3—C2	120.12 (15)	O1—C8—C8i	104.96 (15)
C4—C3—H3	119.9	O1—C8—H8A	110.8
C2—C3—H3	119.9	C8i—C8—H8A	110.8
C5—C4—C3	120.33 (15)	O1—C8—H8B	110.8
C5—C4—H4	119.8	C8i—C8—H8B	110.8
C3—C4—H4	119.8	H8A—C8—H8B	108.8