(S)-2-[(2-Ammonio­phenyl)­sulfanyl­methyl]pyrrolidinium dibromide

In the title compound, C₁₁H₁₈N₂S²⁺·2Br^-, the pyrrolidine ring displays a half-chair conformation, with the flap C atom lying 0.522 (5) Å out of the plane of the other four atoms. The methyl­ene C atom, which connects the pyrrolidinium ring and the thio­ether group, is displaced from the plane of four pyrrolidinium atoms by 0.690 (6) Å in the same direction as the flap C atom. The plane of four pyrrolidinium atoms is almost perpendicular to the benzene ring [dihedral angle = 75.02 (4)°]. The crystal structure is stabilized by hydrogen bonds between the N and Br atoms.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.014 Å
• R factor = 0.058
• wR factor = 0.134
• Data-to-parameter ratio = 21.0

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.103     0.137
            Tmin and Tmax expected:      0.085     0.137
            RR =      1.212
            Please check that your absorption correction is appropriate.
RINTA01_ALERT_3_C  The value of Rint is greater than 0.10
            Rint given   0.135
PLAT020_ALERT_3_C The value of Rint is greater than 0.10 .........       0.14
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N1
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         14
PLAT060_ALERT_4_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large .......       1.17
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          2
              Br
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          3
              Br
PLAT850_ALERT_4_C Check Flack Parameter Exact Value 0.00 and su ..       0.02

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.00
           From the CIF: _reflns_number_total               3311
           Count of symmetry unique reflns         1917
           Completeness (_total/calc)            172.72%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1394
           Fraction of Friedel pairs measured     0.727
           Are heavy atom types Z>Si present        yes
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT791_ALERT_4_G Confirm the Absolute Configuration of C4     ...          S

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
  10 ALERT level C = Check and explain
   5 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   6 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

In recent years, the field of asymmetric organocatalysis has developed rapidly, attracting an increasing number of research groups around the world (Seayad & List, 2005). The title compound, readily synthesized from commercially available L-proline and 2-aminobenzenethiol, could act as an organocatalyst in the Michael addition of ketones to nitrostyrenes. The reaction gave the desired Michael adducts in good yields and high enantioselectivities. The structure of (S)-2-((2-ammoniophenylthio)methyl)pyrrolidinium dibromide is shown in Fig. 1.

The crystal is built of doubly protonated cations and bromide anions. The pyrrolidine ring displays a half-chair conformation, with the flap C atom lying 0.522 (5) Å from the remaining four atoms of the pyrrolidine which are almost coplanar. The methylene C atom, which connects the pyrrolidinium ring and the thioether group, is displaced from the plane of four pyrrolidinium atoms by 0.690 (6) Å in the same direction, as the flap C atom. The plane of four pyrrolidinium ring atoms is almost perpendicular to the benzene ring [dihedral angle 75.02 (4) °]. The crystal structure is stabilized by hydrogen-bonds between the N and Br atoms. The molecular packing of the title compound showing H-bridge interactions between cationic-anionic groups is shown in Fig. 2.

Related literature

The synthesis of (S)-(+)-2-bromomethylpyrrolidine hydrobromide is described by Xu et al. (2006). The development of asymmetric organocatalysis is reviewed by Seayad & List (2005).

S2. Experimental

The title compound was synthesized by treating 2-aminobenzenethiol (1.25 g,10 mmol) with (S)-2-bromomethylpyrrolidine hydrobromide (2.47 g,10 mmol) in MeCN (30 ml) under stirring at 353 K for 24 h (yield 87%). The compound (S)-2-bromomethylpyrrolidine hydrobromide was obtained from commercially available L-proline by reduction with NaBH₄ and subsequent bromination with PBr₃ (Xu et al., 2006). Suitable crystals of the title compound were obtained by slow evaporation of an ethanol solution at room temperature.

S3. Refinement

All carbon-bonded H atoms were placed in calculated positions with C—H = 0.93 Å (C_ar), C—H = 0.98 Å (R₃CH), C—H = 0.97 Å (R₂CH₂) and refined using a riding model, with U_iso(H)=1.2_eq(C). NH₃ hydrogen atoms were located in a difference map and refined with an N—H distance restraint of 0.83 (1) Å, with U value being 0.06, 0.06, 0.09 respectively, while NH₂ hydrogens were treated using a riding model with N—H distance of 0.90 Å.

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The asymmetric unit of the title compound with the atomic labeling scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The molecular packing of the title compound showing H-bridge interactions between cationic-anionic groups.

(S)-2-[(2-Ammoniophenyl)sulfanylmethyl]pyrrolidinium dibromide

Crystal data

C11H18N2S^2+·2Br^−	F(000) = 736
Mr = 370.15	Dx = 1.617 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 1525 reflections
a = 7.9399 (9) Å	θ = 4.4–38.3°
b = 10.8427 (13) Å	µ = 5.45 mm^−1
c = 17.658 (2) Å	T = 293 K
V = 1520.2 (3) Å^3	Prismatic, colorless
Z = 4	0.49 × 0.42 × 0.37 mm

Data collection

Bruker SMART CCD area-detector diffractometer	3311 independent reflections
Radiation source: fine-focus sealed tube	1808 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.136
ϕ and ω scans	θmax = 27.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→10
Tmin = 0.103, Tmax = 0.137	k = −13→12
8969 measured reflections	l = −22→18

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.058	w = 1/[σ^2(Fo^2) + (0.049P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.134	(Δ/σ)max < 0.001
S = 0.83	Δρmax = 0.67 e Å^−3
3311 reflections	Δρmin = −0.50 e Å^−3
158 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
3 restraints	Extinction coefficient: 0.0005 (1)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1394 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.00 (2)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > 2σ(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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.30470 (12)	−0.24305 (9)	−0.08797 (5)	0.0559 (3)
Br2	−0.38177 (12)	0.34415 (8)	0.06967 (5)	0.0526 (3)
S1	−0.0443 (3)	0.1034 (2)	0.14946 (13)	0.0524 (6)
N1	0.0399 (9)	0.3571 (6)	0.0600 (4)	0.0502 (18)
H1A	0.0636	0.2939	0.0288	0.060*
H1B	−0.0728	0.3650	0.0630	0.060*
N2	0.1147 (12)	−0.0815 (8)	0.0452 (5)	0.0487 (18)
C1	0.1159 (18)	0.4726 (9)	0.0308 (7)	0.083 (3)
H1C	0.0296	0.5273	0.0111	0.100*
H1D	0.1959	0.4549	−0.0093	0.100*
C2	0.2025 (14)	0.5297 (9)	0.0973 (7)	0.072 (3)
H2A	0.3237	0.5225	0.0921	0.087*
H2B	0.1735	0.6164	0.1013	0.087*
C3	0.1443 (14)	0.4625 (9)	0.1640 (6)	0.068 (3)
H3A	0.0420	0.4990	0.1840	0.081*
H3B	0.2297	0.4627	0.2033	0.081*
C4	0.1120 (12)	0.3339 (8)	0.1362 (4)	0.049 (2)
H4	0.2194	0.2901	0.1309	0.059*
C5	−0.0079 (11)	0.2577 (8)	0.1852 (4)	0.052 (2)
H5A	−0.1150	0.3004	0.1885	0.062*
H5B	0.0381	0.2519	0.2359	0.062*
C6	0.1553 (11)	0.0316 (8)	0.1640 (5)	0.047 (2)
C7	0.2504 (11)	0.0537 (9)	0.2270 (5)	0.056 (3)
H7	0.2117	0.1092	0.2632	0.068*
C8	0.4032 (13)	−0.0049 (10)	0.2382 (6)	0.073 (3)
H8	0.4680	0.0138	0.2805	0.087*
C9	0.4579 (14)	−0.0887 (10)	0.1879 (6)	0.071 (3)
H9	0.5602	−0.1285	0.1956	0.085*
C10	0.3611 (11)	−0.1161 (8)	0.1239 (5)	0.053 (2)
H10	0.3980	−0.1750	0.0893	0.063*
C11	0.2112 (12)	−0.0555 (8)	0.1123 (5)	0.045 (2)
H2C	0.157 (10)	−0.127 (6)	0.012 (4)	0.06 (3)*
H2D	0.094 (12)	−0.032 (6)	0.010 (3)	0.06 (3)*
H2E	0.043 (10)	−0.135 (7)	0.054 (6)	0.09 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0514 (6)	0.0627 (5)	0.0536 (6)	0.0081 (5)	−0.0055 (4)	−0.0024 (5)
Br2	0.0526 (6)	0.0614 (5)	0.0438 (5)	0.0072 (5)	−0.0041 (4)	−0.0022 (5)
S1	0.0412 (14)	0.0682 (15)	0.0479 (14)	0.0052 (12)	0.0015 (11)	0.0049 (12)
N1	0.045 (4)	0.060 (4)	0.046 (4)	0.007 (4)	0.004 (3)	−0.001 (4)
N2	0.054 (5)	0.048 (5)	0.044 (5)	−0.003 (5)	0.002 (5)	−0.002 (4)
C1	0.105 (10)	0.061 (7)	0.084 (8)	0.010 (7)	0.005 (8)	0.006 (6)
C2	0.055 (7)	0.055 (6)	0.107 (10)	0.005 (5)	0.010 (7)	−0.017 (6)
C3	0.062 (8)	0.074 (7)	0.067 (7)	−0.006 (6)	−0.007 (6)	−0.021 (6)
C4	0.038 (5)	0.066 (6)	0.044 (5)	0.015 (5)	0.000 (4)	0.003 (5)
C5	0.053 (6)	0.070 (6)	0.033 (4)	0.019 (6)	0.002 (4)	−0.009 (5)
C6	0.033 (6)	0.062 (6)	0.046 (5)	0.008 (4)	−0.006 (4)	0.010 (4)
C7	0.043 (6)	0.077 (7)	0.048 (6)	0.012 (5)	0.003 (5)	0.000 (5)
C8	0.062 (8)	0.102 (8)	0.055 (7)	0.010 (7)	−0.022 (6)	−0.008 (6)
C9	0.054 (7)	0.103 (8)	0.056 (7)	0.028 (7)	−0.005 (6)	−0.001 (6)
C10	0.046 (6)	0.061 (6)	0.051 (5)	0.022 (5)	0.011 (5)	0.010 (4)
C11	0.044 (6)	0.059 (6)	0.031 (5)	0.000 (5)	0.000 (4)	0.007 (4)

Geometric parameters (Å, º)

Br1—H2C	2.47 (7)	C3—C4	1.500 (12)
Br2—H1B	2.4665	C3—H3A	0.9700
S1—C6	1.784 (8)	C3—H3B	0.9700
S1—C5	1.811 (9)	C4—C5	1.529 (12)
N1—C1	1.483 (12)	C4—H4	0.9800
N1—C4	1.484 (10)	C5—H5A	0.9700
N1—H1A	0.9000	C5—H5B	0.9700
N1—H1B	0.9000	C6—C7	1.366 (11)
N2—C11	1.438 (11)	C6—C11	1.388 (11)
N2—H2C	0.84 (7)	C7—C8	1.383 (13)
N2—H2D	0.84 (6)	C7—H7	0.9300
N2—H2E	0.83 (8)	C8—C9	1.343 (13)
C1—C2	1.495 (14)	C8—H8	0.9300
C1—H1C	0.9700	C9—C10	1.399 (13)
C1—H1D	0.9700	C9—H9	0.9300
C2—C3	1.460 (13)	C10—C11	1.374 (12)
C2—H2A	0.9700	C10—H10	0.9300
C2—H2B	0.9700
C6—S1—C5	102.2 (4)	N1—C4—C3	101.8 (7)
C1—N1—C4	107.5 (8)	N1—C4—C5	111.3 (7)
C1—N1—H1A	110.2	C3—C4—C5	115.1 (8)
C4—N1—H1A	110.2	N1—C4—H4	109.4
C1—N1—H1B	110.2	C3—C4—H4	109.4
C4—N1—H1B	110.2	C5—C4—H4	109.4
H1A—N1—H1B	108.5	C4—C5—S1	113.7 (6)
C11—N2—H2C	118 (6)	C4—C5—H5A	108.8
C11—N2—H2D	126 (6)	S1—C5—H5A	108.8
H2C—N2—H2D	87 (7)	C4—C5—H5B	108.8
C11—N2—H2E	111 (7)	S1—C5—H5B	108.8
H2C—N2—H2E	90 (9)	H5A—C5—H5B	107.7
H2D—N2—H2E	117 (10)	C7—C6—C11	118.6 (8)
N1—C1—C2	105.3 (9)	C7—C6—S1	122.1 (7)
N1—C1—H1C	110.7	C11—C6—S1	119.1 (7)
C2—C1—H1C	110.7	C6—C7—C8	121.3 (9)
N1—C1—H1D	110.7	C6—C7—H7	119.3
C2—C1—H1D	110.7	C8—C7—H7	119.3
H1C—C1—H1D	108.8	C9—C8—C7	120.0 (10)
C3—C2—C1	106.3 (8)	C9—C8—H8	120.0
C3—C2—H2A	110.5	C7—C8—H8	120.0
C1—C2—H2A	110.5	C8—C9—C10	120.1 (9)
C3—C2—H2B	110.5	C8—C9—H9	120.0
C1—C2—H2B	110.5	C10—C9—H9	120.0
H2A—C2—H2B	108.7	C11—C10—C9	119.6 (9)
C2—C3—C4	104.7 (7)	C11—C10—H10	120.2
C2—C3—H3A	110.8	C9—C10—H10	120.2
C4—C3—H3A	110.8	C10—C11—C6	120.3 (8)
C2—C3—H3B	110.8	C10—C11—N2	119.4 (8)
C4—C3—H3B	110.8	C6—C11—N2	120.3 (8)
H3A—C3—H3B	108.9
C4—N1—C1—C2	−12.2 (11)	C11—C6—C7—C8	2.8 (14)
N1—C1—C2—C3	−12.1 (11)	S1—C6—C7—C8	178.6 (8)
C1—C2—C3—C4	31.4 (11)	C6—C7—C8—C9	−2.4 (15)
C1—N1—C4—C3	30.7 (10)	C7—C8—C9—C10	0.5 (16)
C1—N1—C4—C5	153.8 (8)	C8—C9—C10—C11	1.0 (15)
C2—C3—C4—N1	−38.0 (10)	C9—C10—C11—C6	−0.6 (13)
C2—C3—C4—C5	−158.6 (8)	C9—C10—C11—N2	178.2 (9)
N1—C4—C5—S1	64.5 (8)	C7—C6—C11—C10	−1.3 (12)
C3—C4—C5—S1	179.7 (7)	S1—C6—C11—C10	−177.2 (6)
C6—S1—C5—C4	69.0 (6)	C7—C6—C11—N2	180.0 (8)
C5—S1—C6—C7	38.7 (8)	S1—C6—C11—N2	4.1 (11)
C5—S1—C6—C11	−145.6 (7)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2E···Br1^i	0.83 (8)	2.39 (8)	3.201 (9)	169 (10)
N2—H2D···Br2^ii	0.84 (6)	2.48 (4)	3.277 (9)	159 (8)
N2—H2C···Br1	0.84 (7)	2.47 (7)	3.298 (9)	173 (8)
N1—H1B···Br2	0.90	2.47	3.355 (7)	169
N1—H1A···Br2^ii	0.90	2.33	3.224 (7)	170

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