2-Methyl-1-(pyrrolidinium-2-ylmethyl)­pyridinium dibromide

Wang, L.; Yue, H.; Liu, X.; Luo, S.; Xu, D.

doi:10.1107/S1600536807048003

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2-Methyl-1-(pyrrolidinium-2-ylmethyl)pyridinium dibromide

L. Wang, H. Yue, X. Liu, S. Luo and D. Xu

In the title compound, C₁₁H₁₈N₂²⁺·2Br⁻, whose cation represents the product of racemization of an L-proline derivative under basic conditions, the pyrrolidinium ring has a distorted envelope conformation with the N atom deviating by 0.533 (6) Å from the mean plane of the remaining four atoms of the ring. The methylene C atom which connects the pyrrolidinium ring and the 2-methylpyridine group is displaced from the plane of the four pyrrolidinium C atoms by 0.625 (8) Å in the same direction as the N atom. The cation and anions are linked by N—H

Br hydrogen bonds.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807048003/ya2056sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807048003/ya2056Isup2.hkl Contains datablock I

CCDC reference: 669136

checkCIF report

Key indicators

Single-crystal X-ray study
T = 298 K
Mean (C-C) = 0.008 Å
R factor = 0.045
wR factor = 0.139
Data-to-parameter ratio = 23.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT230_ALERT_2_B Hirshfeld Test Diff for    C8     -   C9      ..       8.11 su
PLAT230_ALERT_2_B Hirshfeld Test Diff for    C10    -   C11     ..      13.23 su
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for        C10

Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C2
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C7
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C9
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          8

Alert level G
PLAT793_ALERT_1_G Check the Absolute Configuration of C4     = ...          S

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

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

Comment top

There has been growing interest (Ishii et al., 2004; Andrey et al., 2004) in the studies of catalytic properties of proline and its derivatives. The title compound (I), a quaternary ammonium salt obtained from L-proline, can act as organocatalyst in several important processes such as the Michael reaction, the Mannich reaction and others. When this compound was used as a catalyst of the Michael addition of cyclohexanone to nitroolefins, the products were obtained in good yields, however the reactions showed poor enantioselectivities. In order to establish the structure of (I) unambiguously, as well as to investigate the reason for the above mentioned lack of enantioselectivity, the X-ray analysis of (I) was undertaken. The structure of (I) is shown in Fig. 1.

It came as a surprise, that the crystal of (I) turned out to be racemic and crystallize in centrosymmetric space group, even though it was prepared from the chiral L-proline derivative. It is known however that in basic conditions under heating L-proline and its derivatives may undergo racemization (Ebbers et al., 1997).

The crystal of (I) is built of pyrrolidinium dications and bromide anions. The N21 atom of the pyrrolidinium ring and the C5 atom are displaced from the mean plane of C1, C2, C3, C4 in the same direction by 0.533 (6) and 0.625 (8) Å. Thanks to two N—H···Br bonds (Table 2) the dications and anions form "ion-pairs" in crystal of (I).

Related literature top

See Ishii et al. (2004) and Andrey et al. (2004) for the catalytic properties of L-proline. The synthesis of (S)-(+)-2-bromomethylpyrrolidine hydrobromide is described by Xu et al. (2006). Details of the racemization of amino acids under basic conditions are given by Ebbers et al. (1997). For the method used for the extinction correction, see: Larson (1970).

Experimental top

The title compound was synthesized by treating of 2-methylpyridine (1.10 g, 11 mmol) with (S)-(+)-2-bromomethylpyrrolidine hydrobromide (2.50 g, 10 mmol; see Xu et al., 2006 for the synthesis of the latter) in MeCN (30 ml) under stirring at 353 K for 24 h (yield 95%). The reaction is accompanied by racemization of the L-proline derivative. Suitable crystals of the title compound were obtained by slow evaporation of ethanol solution at room temperature (m.p. 421 K).

Structure description top

Computing details top

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC & Rigaku, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: CRYSTALS (Watkin et al., 1996); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: CrystalStructure (Rigaku/MSC & Rigaku, 2004).

Figures top

Fig. 1. The asymmetric unit of the structure of the title compound, with the atomic labeling scheme. Displacement ellipsoids are drawn at the 40% probability level. Atomic labels are shown only for those H atoms which participate in the H-bonding.

2-Methyl-1-(pyrrolidinium-2-ylmethyl)pyridinium dibromide top

Crystal data top

C₁₁H₁₈N₂²⁺·2Br⁻	F(000) = 672.00
M_r = 338.08	D_x = 1.612 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 148 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71075 Å
a = 12.588 (3) Å	Cell parameters from 9608 reflections
b = 10.023 (4) Å	θ = 3.1–27.5°
c = 12.461 (4) Å	µ = 5.81 mm⁻¹
β = 117.617 (13)°	T = 298 K
V = 1393.1 (8) Å³	Block, yellow
Z = 4	0.26 × 0.19 × 0.17 mm

Data collection top

Rigaku R-AXIS RAPID diffractometer	2192 reflections with I > 2σ(I)
Detector resolution: 10.00 pixels mm^-1	R_int = 0.032
ω scans	θ_max = 27.5°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −16→16
T_min = 0.225, T_max = 0.372	k = −12→13
13165 measured reflections	l = −14→16
3178 independent reflections

Refinement top

Refinement on F²	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.045	w = 1/[0.0017F_o² + 1.0σ(F_o²)]/(4F_o²)
wR(F²) = 0.139	(Δ/σ)_max < 0.001
S = 1.01	Δρ_max = 0.88 e Å⁻³
3178 reflections	Δρ_min = −0.69 e Å⁻³
137 parameters	Extinction correction: Larson (1970)
0 restraints	Extinction coefficient: 28 (2)

Crystal data top

C₁₁H₁₈N₂²⁺·2Br⁻	V = 1393.1 (8) Å³
M_r = 338.08	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 12.588 (3) Å	µ = 5.81 mm⁻¹
b = 10.023 (4) Å	T = 298 K
c = 12.461 (4) Å	0.26 × 0.19 × 0.17 mm
β = 117.617 (13)°

Data collection top

Rigaku R-AXIS RAPID diffractometer	3178 independent reflections
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	2192 reflections with I > 2σ(I)
T_min = 0.225, T_max = 0.372	R_int = 0.032
13165 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.045	0 restraints
wR(F²) = 0.139	H-atom parameters constrained
S = 1.01	Δρ_max = 0.88 e Å⁻³
3178 reflections	Δρ_min = −0.69 e Å⁻³
137 parameters

Special details top

Refinement. Refinement using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

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

	x	y	z	U_iso*/U_eq
Br1	0.41438 (4)	0.56892 (5)	0.64583 (4)	0.06054 (16)
Br2	0.08574 (4)	0.16025 (5)	0.45070 (4)	0.05775 (16)
N21	0.3228 (3)	0.3124 (3)	0.4761 (2)	0.0487 (9)
N22	0.1717 (2)	0.5515 (3)	0.3133 (2)	0.0516 (10)
C1	0.4223 (4)	0.2119 (6)	0.5167 (5)	0.0741 (17)
C2	0.4018 (6)	0.1369 (6)	0.4052 (5)	0.094 (2)
C3	0.3048 (5)	0.2097 (5)	0.2990 (4)	0.0762 (18)
C4	0.2946 (3)	0.3451 (4)	0.3492 (3)	0.0481 (12)
C5	0.1739 (4)	0.4108 (4)	0.2777 (3)	0.0511 (12)
C6	0.1146 (4)	0.5837 (6)	0.3801 (4)	0.087 (2)
C7	0.1090 (7)	0.7146 (7)	0.4121 (7)	0.119 (3)
C8	0.1624 (7)	0.8095 (9)	0.3721 (7)	0.106 (3)
C9	0.2193 (5)	0.7798 (4)	0.3032 (5)	0.106 (2)
C10	0.2226 (3)	0.6472 (3)	0.2744 (4)	0.0577 (13)
C11	0.2778 (6)	0.6100 (7)	0.1949 (6)	0.119 (2)
H4	0.3570	0.4043	0.3502	0.058*
H6	0.0792	0.5168	0.4044	0.104*
H7	0.0712	0.7378	0.4582	0.142*
H8	0.1598	0.8982	0.3927	0.127*
H9	0.2539	0.8461	0.2773	0.128*
H101	0.4190	0.1520	0.5763	0.089*
H102	0.4995	0.2563	0.5514	0.089*
H111	0.3484	0.5576	0.2404	0.143*
H112	0.2213	0.5592	0.1271	0.143*
H113	0.2989	0.6896	0.1663	0.143*
H201	0.3764	0.0464	0.4090	0.112*
H202	0.4750	0.1345	0.3974	0.112*
H211	0.3489	0.3871	0.5289	0.057*
H212	0.2604	0.2740	0.4796	0.057*
H301	0.3271	0.2205	0.2347	0.091*
H302	0.2295	0.1617	0.2683	0.091*
H501	0.1534	0.4084	0.1925	0.061*
H502	0.1146	0.3610	0.2905	0.061*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0632 (3)	0.0577 (3)	0.0598 (3)	−0.0061 (2)	0.0278 (2)	−0.0152 (2)
Br2	0.0576 (3)	0.0641 (3)	0.0493 (3)	−0.0091 (2)	0.0228 (2)	0.0049 (2)
N21	0.0508 (19)	0.050 (2)	0.0420 (18)	−0.0043 (16)	0.0184 (15)	−0.0055 (15)
N22	0.0438 (18)	0.064 (2)	0.0402 (18)	0.0065 (17)	0.0138 (14)	−0.0026 (17)
C1	0.071 (3)	0.074 (3)	0.068 (3)	0.024 (2)	0.024 (2)	0.005 (2)
C2	0.125 (5)	0.070 (4)	0.074 (3)	0.039 (3)	0.036 (3)	0.005 (3)
C3	0.112 (4)	0.060 (3)	0.062 (3)	0.015 (3)	0.045 (3)	−0.008 (2)
C4	0.057 (2)	0.043 (2)	0.048 (2)	−0.0016 (19)	0.0284 (19)	−0.0019 (18)
C5	0.056 (2)	0.050 (2)	0.041 (2)	−0.012 (2)	0.0174 (18)	−0.0013 (19)
C6	0.053 (2)	0.147 (6)	0.051 (2)	0.025 (3)	0.017 (2)	−0.004 (3)
C7	0.087 (5)	0.153 (12)	0.079 (5)	0.023 (6)	0.008 (4)	−0.019 (7)
C8	0.081 (7)	0.110 (8)	0.075 (6)	0.067 (6)	−0.007 (4)	−0.012 (5)
C9	0.087 (4)	0.058 (3)	0.107 (5)	0.011 (3)	−0.012 (4)	−0.007 (3)
C10	0.051 (2)	0.044 (2)	0.061 (2)	0.002 (2)	0.011 (2)	0.006 (2)
C11	0.148 (6)	0.089 (5)	0.110 (5)	−0.021 (5)	0.052 (5)	0.030 (4)

Geometric parameters (Å, º) top

N21—C1	1.500 (6)	C1—H101	0.970
N21—C4	1.488 (6)	C1—H102	0.970
N22—C5	1.483 (5)	C2—H201	0.970
N22—C6	1.367 (7)	C2—H202	0.970
N22—C10	1.361 (6)	C3—H301	0.970
C1—C2	1.494 (9)	C3—H302	0.970
C2—C3	1.509 (7)	C4—H4	0.980
C3—C4	1.524 (7)	C5—H501	0.970
C4—C5	1.511 (5)	C5—H502	0.970
C6—C7	1.383 (10)	C6—H6	0.930
C7—C8	1.384 (13)	C7—H7	0.930
C8—C9	1.382 (13)	C8—H8	0.930
C9—C10	1.382 (6)	C9—H9	0.930
C10—C11	1.496 (11)	C11—H111	0.960
N21—H211	0.949	C11—H112	0.960
N21—H212	0.895	C11—H113	0.960

Br1···N21	3.186 (3)	H101···H201^ix	3.192
Br2···N21	3.234 (4)	H101···H202^ix	3.119
Br2···N22ⁱ	3.554 (2)	H101···H301^vi	2.998
Br2···C10ⁱ	3.586 (3)	H102···Br1ⁱⁱⁱ	3.571
N21···Br1	3.186 (3)	H102···C9ⁱⁱⁱ	3.161
N21···Br2	3.234 (4)	H102···C10ⁱⁱⁱ	3.293
N22···Br2ⁱⁱ	3.554 (2)	H102···C11ⁱⁱⁱ	3.381
C10···Br2ⁱⁱ	3.586 (3)	H102···H9ⁱⁱⁱ	3.017
Br1···H4ⁱⁱⁱ	2.868	H102···H111ⁱⁱⁱ	3.045
Br1···H9^iv	3.250	H102···H113ⁱⁱⁱ	3.292
Br1···H101^v	3.217	H102···H201^ix	3.343
Br1···H102ⁱⁱⁱ	3.571	H111···Br1ⁱⁱⁱ	2.934
Br1···H111ⁱⁱⁱ	2.934	H111···H101^xiii	3.326
Br1···H113^iv	2.895	H111···H102ⁱⁱⁱ	3.045
Br1···H202ⁱⁱⁱ	3.429	H111···H202^xiv	3.467
Br1···H202^vi	3.514	H111···H211ⁱⁱⁱ	3.596
Br1···H211	2.239	H112···Br2^xiii	3.018
Br1···H301ⁱⁱⁱ	3.574	H112···C7^xi	3.288
Br1···H301^vi	3.461	H112···C8^xi	3.193
Br2···H7^vii	2.883	H112···H7^xi	2.908
Br2···H8^viii	2.986	H112···H8^xi	2.686
Br2···H112^vi	3.018	H112···H101^xiii	3.540
Br2···H212	2.351	H113···Br1^xi	2.895
Br2···H302	3.501	H113···C7^xi	3.106
Br2···H501^vi	2.810	H113···C8^xi	3.248
Br2···H502	2.973	H113···H7^xi	2.929
N21···H301^vi	3.215	H113···H8^xi	3.150
C1···H201^ix	3.437	H113···H102ⁱⁱⁱ	3.292
C1···H301^vi	3.505	H113···H202^xiv	3.336
C2···H9^viii	3.428	H201···C1^ix	3.437
C2···H201^ix	3.246	H201···C2^ix	3.246
C2···H202^ix	3.510	H201···C8^viii	3.458
C5···H7ⁱ	3.572	H201···C9^viii	3.221
C7···H112^iv	3.288	H201···H8^viii	3.027
C7···H113^iv	3.106	H201···H9^viii	2.600
C7···H501ⁱⁱ	3.520	H201···H101^ix	3.192
C7···H502ⁱⁱ	3.141	H201···H102^ix	3.343
C8···H112^iv	3.193	H201···H201^ix	3.026
C8···H113^iv	3.248	H201···H202^ix	2.903
C8···H201^x	3.458	H202···Br1ⁱⁱⁱ	3.429
C8···H502ⁱⁱ	3.160	H202···Br1^xiii	3.514
C9···H102ⁱⁱⁱ	3.161	H202···C2^ix	3.510
C9···H201^x	3.221	H202···H101^ix	3.119
C10···H102ⁱⁱⁱ	3.293	H202···H111^xv	3.467
C11···H7^xi	3.268	H202···H113^xv	3.336
C11···H8^xi	3.348	H202···H201^ix	2.903
C11···H102ⁱⁱⁱ	3.381	H202···H202^ix	3.566
H4···Br1ⁱⁱⁱ	2.868	H211···Br1	2.239
H7···Br2^vii	2.883	H211···H111ⁱⁱⁱ	3.596
H7···C5ⁱⁱ	3.572	H211···H301^vi	2.910
H7···C11^iv	3.268	H212···Br2	2.351
H7···H112^iv	2.908	H212···H301^vi	2.888
H7···H113^iv	2.929	H301···Br1ⁱⁱⁱ	3.574
H7···H501ⁱⁱ	3.086	H301···Br1^xiii	3.461
H7···H502ⁱⁱ	3.144	H301···N21^xiii	3.215
H8···Br2^x	2.986	H301···C1^xiii	3.505
H8···C11^iv	3.348	H301···H101^xiii	2.998
H8···H112^iv	2.686	H301···H211^xiii	2.910
H8···H113^iv	3.150	H301···H212^xiii	2.888
H8···H201^x	3.027	H302···Br2	3.501
H8···H302^x	3.378	H302···H8^viii	3.378
H8···H501ⁱⁱ	3.578	H302···H9^viii	3.175
H8···H502ⁱⁱ	3.159	H501···Br2^xiii	2.810
H9···Br1^xi	3.250	H501···C7ⁱ	3.520
H9···C2^x	3.428	H501···H7ⁱ	3.086
H9···H102ⁱⁱⁱ	3.017	H501···H8ⁱ	3.578
H9···H201^x	2.600	H502···Br2	2.973
H9···H302^x	3.175	H502···C7ⁱ	3.141
H101···Br1^xii	3.217	H502···C8ⁱ	3.160
H101···H111^vi	3.326	H502···H7ⁱ	3.144
H101···H112^vi	3.540	H502···H8ⁱ	3.159

C1—N21—C4	104.9 (4)	C3—C2—H201	110.1
C5—N22—C6	119.6 (4)	C3—C2—H202	110.1
C5—N22—C10	119.1 (4)	H201—C2—H202	109.5
C6—N22—C10	121.2 (4)	C2—C3—H301	110.6
N21—C1—C2	105.5 (4)	C2—C3—H302	110.6
C1—C2—C3	107.0 (5)	C4—C3—H301	110.6
C2—C3—C4	105.0 (4)	C4—C3—H302	110.6
N21—C4—C3	102.5 (3)	H301—C3—H302	109.5
N21—C4—C5	113.7 (4)	N21—C4—H4	109.0
C3—C4—C5	113.5 (3)	C3—C4—H4	109.0
N22—C5—C4	113.0 (3)	C5—C4—H4	109.0
N22—C6—C7	120.7 (6)	N22—C5—H501	108.6
C6—C7—C8	116.8 (9)	N22—C5—H502	108.6
C7—C8—C9	123.6 (8)	C4—C5—H501	108.6
C8—C9—C10	117.1 (6)	C4—C5—H502	108.6
N22—C10—C9	120.6 (5)	H501—C5—H502	109.5
N22—C10—C11	120.0 (4)	N22—C6—H6	119.7
C9—C10—C11	119.3 (5)	C7—C6—H6	119.7
C1—N21—H211	109.2	C6—C7—H7	121.6
C1—N21—H212	108.0	C8—C7—H7	121.6
C4—N21—H211	113.5	C7—C8—H8	118.2
C4—N21—H212	111.3	C9—C8—H8	118.2
H211—N21—H212	109.6	C8—C9—H9	121.5
N21—C1—H101	110.5	C10—C9—H9	121.5
N21—C1—H102	110.5	C10—C11—H111	109.5
C2—C1—H101	110.5	C10—C11—H112	109.5
C2—C1—H102	110.5	C10—C11—H113	109.5
H101—C1—H102	109.5	H111—C11—H112	109.5
C1—C2—H201	110.1	H111—C11—H113	109.5
C1—C2—H202	110.1	H112—C11—H113	109.5

C1—N21—C4—C3	39.2 (4)	N21—C1—C2—C3	9.6 (7)
C1—N21—C4—C5	162.2 (3)	C1—C2—C3—C4	14.4 (7)
C4—N21—C1—C2	−30.8 (5)	C2—C3—C4—N21	−32.9 (6)
C5—N22—C6—C7	−178.5 (4)	C2—C3—C4—C5	−155.9 (5)
C6—N22—C5—C4	−106.0 (4)	N21—C4—C5—N22	73.6 (5)
C5—N22—C10—C9	178.2 (3)	C3—C4—C5—N22	−169.7 (4)
C5—N22—C10—C11	1.1 (5)	N22—C6—C7—C8	0.7 (7)
C10—N22—C5—C4	76.7 (4)	C6—C7—C8—C9	0.2 (7)
C6—N22—C10—C9	1.0 (5)	C7—C8—C9—C10	−0.4 (9)
C6—N22—C10—C11	−176.2 (3)	C8—C9—C10—N22	−0.1 (5)
C10—N22—C6—C7	−1.3 (6)	C8—C9—C10—C11	177.0 (5)

Symmetry codes: (i) −x, y−1/2, −z+1/2; (ii) −x, y+1/2, −z+1/2; (iii) −x+1, −y+1, −z+1; (iv) x, −y+3/2, z+1/2; (v) −x+1, y+1/2, −z+3/2; (vi) x, −y+1/2, z+1/2; (vii) −x, −y+1, −z+1; (viii) x, y−1, z; (ix) −x+1, −y, −z+1; (x) x, y+1, z; (xi) x, −y+3/2, z−1/2; (xii) −x+1, y−1/2, −z+3/2; (xiii) x, −y+1/2, z−1/2; (xiv) −x+1, y+1/2, −z+1/2; (xv) −x+1, y−1/2, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N21—H211···Br1	0.95	2.24	3.186 (3)	176
N21—H212···Br2	0.90	2.35	3.233 (3)	169

Experimental details

Crystal data
Chemical formula	C₁₁H₁₈N₂²⁺·2Br⁻
M_r	338.08
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	12.588 (3), 10.023 (4), 12.461 (4)
β (°)	117.617 (13)
V (Å³)	1393.1 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	5.81
Crystal size (mm)	0.26 × 0.19 × 0.17

Data collection
Diffractometer	Rigaku R-AXIS RAPID
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995)
T_min, T_max	0.225, 0.372
No. of measured, independent and observed [I > 2σ(I)] reflections	13165, 3178, 2192
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.139, 1.01
No. of reflections	3178
No. of parameters	137
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.88, −0.69

Computer programs: PROCESS-AUTO (Rigaku, 1998), CrystalStructure (Rigaku/MSC & Rigaku, 2004), SHELXS97 (Sheldrick, 1997), CRYSTALS (Watkin et al., 1996), ORTEP-3 for Windows (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N21—H211···Br1	0.949	2.238	3.186 (3)	176
N21—H212···Br2	0.895	2.351	3.233 (3)	169

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