2-(Eth­oxy­carbono­thio­ylthio)­propanoic acid

Eyer, L.N.; McAdam, C.J.; Simpson, J.

doi:10.1107/S2414314617010355

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 2| Part 7| July 2017| x171035

https://doi.org/10.1107/S2414314617010355

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2-(Ethoxycarbonothioylthio)propanoic acid

Lukas N. Eyer,^a C. John McAdam ^a and Jim Simpson ^a ^*

^aDepartment of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand
^*Correspondence e-mail: jsimpson@alkali.otago.ac.nz

Edited by P. C. Healy, Griffith University, Australia (Received 12 July 2017; accepted 13 July 2017; online 18 July 2017)

In the title compound, C₆H₁₀O₃S₂, the O,S-diethyl carbonodithioate segment of the molecule is almost planar and is inclined to the carboxylic acid substituent by 82.31 (8)°. In the crystal, O—H⋯O, C—H⋯O and C—H⋯S hydrogen bonds each form inversion dimers and combine with a short O⋯S contact of 3.2394 (16) Å to generate a three-dimensional network of molecules stacked along all three axial directions.

Keywords: crystal structure; 2-(ethoxycarbonothioylthio)propanoic acid; inversion dimers; hydrogen bonds.

CCDC reference: 1561912

Structure description

The title compound is a commonly used reversible addition–fragmentation chain-transfer (RAFT) polymerization agent (Nakabayashi et al., 2016 ; Peng et al., 2016 ). The Cambridge Structural Database (Version 5.38 with three updates; Groom et al., 2016 ) reveals only four closely related compounds with the H—O—C(=O)—C—S—C(=S)—O skeleton of the title compound. Only two of these, namely 2-[(ethoxycarbonothioyl)sulfanyl]acetic acid (CSD refcode EROTAH; Xiao et al., 2011 ) and 2-(O-ethyl dithiocarbonato)succinic acid (JAPHEN; Duarte et al., 1989 ) have ethoxy substituents on the dithiocarbonyl unit. The other two analogues have methoxy (ULEHAV; Xiao & Charpentier, 2011 ) and isopropoxy (WACQOI; Xiao & Charpentier, 2010 ) substituents in these positions.

The C3—C2—S2—C4(=S1)—O3—C5—C6 segment of the title molecule (Fig. 1) is almost planar, with an r.m.s. deviation of 0.0859 Å from the best-fit plane through all eight non-H atoms. The C2—C1(=O1)—O2 carboxylic acid unit is also close to planar, with an r.m.s. deviation of 0.0106 Å, and is almost orthogonal to the previous plane, with a dihedral angle of 82.31 (8)° between them. In the crystal, classical O2—H2O⋯O1ⁱ and nonclassical C2—H2⋯O1ⁱⁱ and C6—H6A⋯S1ⁱⁱⁱ hydrogen bonds (Table 1) each form inversion dimers, enclosing R₂²(8), R₂²(8) and R₂²(12) ring motifs, respectively (Bernstein et al., 1995 ). In addition, short O1⋯S1^iv contacts [3.2394 (16) Å; symmetry code: (iv) x, y, 1 + z] link adjacent molecules into rows along the c-axis direction. These contacts combine to stack the molecules along all three axial directions (Figs. 2, 3 and 4).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2O⋯O1ⁱ	0.72 (4)	1.92 (4)	2.639 (2)	175 (4)
C2—H2⋯O1ⁱⁱ	1.00	2.62	3.497 (3)	146
C6—H6A⋯S1ⁱⁱⁱ	0.98	2.99	3.759 (2)	136
Symmetry codes: (i) -x+1, -y+1, -z; (ii) -x+2, -y+1, -z; (iii) -x+1, -y+1, -z+1.

Figure 1
The structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. Only the major-disorder component of the S2 atom is shown.

Figure 2
The overall packing of the title compound, viewed along the a-axis direction. In this and Figs. 3

and 4

, only the major-disorder component of the S2 atom is shown in each case.

Figure 3
The overall packing of the title compound, viewed along the b-axis direction.

Figure 4
The overall packing of the title compound, viewed along the c-axis direction.

Synthesis and crystallization

The title compound was prepared according to the literature procedure of Nguyen et al. (2015 ) and X-ray-quality crystals were obtained by recrystallization from mixed solvents of diethyl ether layered with hexane.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Once all of the atoms in the stucture had been found, a high peak remained in the difference Fourier map close to the S2 atom, suggesting possible disorder. Refinement of the two locations of the S2 atom converged with an occupancy ratio of 0.861 (18):0.139 (18).

Table 2
Experimental details

Crystal data
Chemical formula	C₆H₁₀O₃S₂
M_r	194.26
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	100
a, b, c (Å)	7.4093 (4), 7.9779 (3), 8.6250 (3)
α, β, γ (°)	67.300 (4), 85.900 (4), 74.068 (4)
V (Å³)	451.93 (4)
Z	2
Radiation type	Cu Kα
μ (mm⁻¹)	5.04
Crystal size (mm)	0.30 × 0.13 × 0.10

Data collection
Diffractometer	Agilent SuperNova Dual Source diffractometer with an Atlas detector
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2014 )
T_min, T_max	0.637, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	6643, 1875, 1766
R_int	0.064
(sin θ/λ)_max (Å⁻¹)	0.630

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.047, 0.128, 1.06
No. of reflections	1875
No. of parameters	115
No. of restraints	7
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.62, −0.60
Computer programs: CrysAlis PRO (Agilent, 2014), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), TITAN (Hunter & Simpson, 1999 ), Mercury (Macrae et al., 2008 ), enCIFer (Allen et al., 2004 ), PLATON (Spek, 2009 ), publCIF (Westrip, 2010 ) and WinGX (Farrugia, 2012 ).

Structural data

CCDC reference: 1561912

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314617010355/hg4023sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617010355/hg4023Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314617010355/hg4023Isup3.cml

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Agilent, 2014); cell refinement: CrysAlis PRO (Agilent, 2014); data reduction: CrysAlis PRO (Agilent, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b) and TITAN (Hunter & Simpson, 1999); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b), enCIFer (Allen et al., 2004), PLATON (Spek, 2009), publCIF (Westrip, 2010) and WinGX (Farrugia, 2012).

2-(Ethoxycarbonothioylthio)propanoic acid top

Crystal data top

C₆H₁₀O₃S₂	Z = 2
M_r = 194.26	F(000) = 204
Triclinic, P1	D_x = 1.428 Mg m⁻³
a = 7.4093 (4) Å	Cu Kα radiation, λ = 1.54184 Å
b = 7.9779 (3) Å	Cell parameters from 4826 reflections
c = 8.6250 (3) Å	θ = 5.5–75.3°
α = 67.300 (4)°	µ = 5.04 mm⁻¹
β = 85.900 (4)°	T = 100 K
γ = 74.068 (4)°	Rectangular block, colourless
V = 451.93 (4) Å³	0.30 × 0.13 × 0.10 mm

Data collection top

Agilent SuperNova Dual Source diffractometer with an Atlas detector	1875 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	1766 reflections with I > 2σ(I)
Detector resolution: 5.1725 pixels mm^-1	R_int = 0.064
ω scans	θ_max = 76.3°, θ_min = 5.6°
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2014)	h = −9→9
T_min = 0.637, T_max = 1.000	k = −9→10
6643 measured reflections	l = −10→10

Refinement top

Refinement on F²	7 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.047	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.128	w = 1/[σ²(F_o²) + (0.0828P)² + 0.2987P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
1875 reflections	Δρ_max = 0.62 e Å⁻³
115 parameters	Δρ_min = −0.60 e Å⁻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	Occ. (<1)
O1	0.7282 (2)	0.4764 (2)	0.0116 (2)	0.0259 (4)
O2	0.4935 (2)	0.6981 (3)	0.0545 (2)	0.0272 (4)
H2O	0.433 (5)	0.647 (5)	0.042 (4)	0.041*
C1	0.6695 (3)	0.6171 (3)	0.0468 (3)	0.0201 (4)
C2	0.8089 (3)	0.7123 (3)	0.0736 (3)	0.0216 (5)
H2	0.9359	0.6201	0.0989	0.026*
C3	0.8165 (4)	0.8809 (4)	−0.0890 (3)	0.0305 (6)
H3A	0.8454	0.8383	−0.1827	0.046*
H3B	0.9143	0.9365	−0.0761	0.046*
H3C	0.6947	0.9756	−0.1122	0.046*
S2	0.7542 (6)	0.7994 (3)	0.24168 (12)	0.0156 (4)	0.861 (18)
S2A	0.704 (3)	0.829 (2)	0.2403 (9)	0.0171 (18)	0.139 (18)
C4	0.7572 (3)	0.5968 (3)	0.4189 (3)	0.0164 (4)
S1	0.75397 (7)	0.59867 (7)	0.60794 (6)	0.0198 (2)
O3	0.7618 (2)	0.4524 (2)	0.37763 (18)	0.0186 (3)
C5	0.7683 (3)	0.2696 (3)	0.5119 (3)	0.0210 (5)
H5A	0.6612	0.2809	0.5861	0.025*
H5B	0.8866	0.2208	0.5806	0.025*
C6	0.7573 (3)	0.1402 (3)	0.4260 (3)	0.0255 (5)
H6A	0.6388	0.1896	0.3598	0.038*
H6B	0.7633	0.0142	0.5108	0.038*
H6C	0.8628	0.1326	0.3514	0.038*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0334 (9)	0.0282 (10)	0.0246 (8)	−0.0125 (7)	−0.0001 (7)	−0.0159 (7)
O2	0.0306 (9)	0.0216 (9)	0.0329 (9)	−0.0108 (7)	−0.0083 (7)	−0.0100 (7)
C1	0.0253 (10)	0.0193 (11)	0.0158 (9)	−0.0089 (8)	−0.0033 (8)	−0.0041 (8)
C2	0.0251 (10)	0.0215 (11)	0.0206 (10)	−0.0084 (9)	−0.0035 (8)	−0.0083 (9)
C3	0.0420 (14)	0.0304 (14)	0.0237 (11)	−0.0202 (11)	−0.0006 (10)	−0.0078 (10)
S2	0.0174 (9)	0.0106 (5)	0.0188 (4)	−0.0019 (5)	−0.0058 (3)	−0.0058 (3)
S2A	0.019 (2)	0.018 (2)	0.0169 (19)	−0.0070 (11)	−0.0024 (9)	−0.0070 (11)
C4	0.0158 (8)	0.0147 (10)	0.0207 (9)	−0.0042 (7)	−0.0040 (7)	−0.0079 (8)
S1	0.0238 (3)	0.0186 (3)	0.0182 (3)	−0.0035 (2)	−0.0032 (2)	−0.0092 (2)
O3	0.0229 (7)	0.0147 (8)	0.0202 (7)	−0.0055 (6)	−0.0031 (6)	−0.0080 (6)
C5	0.0234 (10)	0.0144 (11)	0.0237 (10)	−0.0041 (8)	−0.0049 (8)	−0.0053 (8)
C6	0.0283 (11)	0.0153 (12)	0.0330 (12)	−0.0039 (9)	−0.0048 (9)	−0.0095 (9)

Geometric parameters (Å, º) top

O1—C1	1.232 (3)	S2A—C4	1.856 (13)
O2—C1	1.296 (3)	C4—O3	1.322 (3)
O2—H2O	0.72 (4)	C4—S1	1.635 (2)
C1—C2	1.515 (3)	S1—O1ⁱ	3.2394 (16)
C2—C3	1.535 (3)	O3—C5	1.462 (3)
C2—S2	1.813 (3)	C5—C6	1.505 (3)
C2—S2A	2.004 (13)	C5—H5A	0.9900
C2—H2	1.0000	C5—H5B	0.9900
C3—H3A	0.9800	C6—H6A	0.9800
C3—H3B	0.9800	C6—H6B	0.9800
C3—H3C	0.9800	C6—H6C	0.9800
S2—C4	1.740 (2)

C1—O2—H2O	112 (3)	O3—C4—S1	127.40 (17)
O1—C1—O2	124.6 (2)	O3—C4—S2	111.49 (15)
O1—C1—C2	118.99 (19)	S1—C4—S2	121.11 (13)
O2—C1—C2	116.27 (19)	O3—C4—S2A	114.6 (3)
C1—C2—C3	108.95 (18)	S1—C4—S2A	116.9 (3)
C1—C2—S2	114.60 (17)	C4—S1—O1ⁱ	162.49 (9)
C3—C2—S2	107.51 (16)	C4—O3—C5	118.71 (16)
C1—C2—S2A	108.0 (4)	O3—C5—C6	106.08 (17)
C3—C2—S2A	104.2 (4)	O3—C5—H5A	110.5
C1—C2—H2	108.5	C6—C5—H5A	110.5
C3—C2—H2	108.5	O3—C5—H5B	110.5
S2—C2—H2	108.5	C6—C5—H5B	110.5
C2—C3—H3A	109.5	H5A—C5—H5B	108.7
C2—C3—H3B	109.5	C5—C6—H6A	109.5
H3A—C3—H3B	109.5	C5—C6—H6B	109.5
C2—C3—H3C	109.5	H6A—C6—H6B	109.5
H3A—C3—H3C	109.5	C5—C6—H6C	109.5
H3B—C3—H3C	109.5	H6A—C6—H6C	109.5
C4—S2—C2	103.40 (14)	H6B—C6—H6C	109.5
C4—S2A—C2	92.4 (7)

O1—C1—C2—C3	97.9 (2)	C2—S2A—C4—O3	−26.7 (7)
O2—C1—C2—C3	−78.7 (2)	C2—S2A—C4—S1	164.1 (2)
O1—C1—C2—S2	−141.7 (2)	O3—C4—S1—O1ⁱ	−9.5 (4)
O2—C1—C2—S2	41.8 (3)	S2—C4—S1—O1ⁱ	170.4 (2)
O1—C1—C2—S2A	−149.6 (5)	S2A—C4—S1—O1ⁱ	158.1 (6)
O2—C1—C2—S2A	33.9 (5)	S1—C4—O3—C5	−1.2 (3)
C1—C2—S2—C4	60.7 (3)	S2—C4—O3—C5	178.92 (19)
C3—C2—S2—C4	−178.06 (19)	S2A—C4—O3—C5	−169.0 (6)
C2—S2—C4—O3	−11.7 (3)	C4—O3—C5—C6	175.74 (17)
C2—S2—C4—S1	168.43 (15)

Symmetry code: (i) x, y, z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2O···O1ⁱⁱ	0.72 (4)	1.92 (4)	2.639 (2)	175 (4)
C2—H2···O1ⁱⁱⁱ	1.00	2.62	3.497 (3)	146
C6—H6A···S1^iv	0.98	2.99	3.759 (2)	136

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

Funding information

Funding for this research was provided by: NZ Ministry of Business Innovation and Employment Science Investment Fund (grant No. UOO-X1206); University of Otago for the purchase of the diffractometer.

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