Redetermination of l-tryptophan hydro-bromide.

The redetermined crystal structure of the title compound, C(11)H(13)N(2)O(2) (+)·Br(-), is reported. Data collection at 100 K about three crystallographic axes resulted in a crystal structure with significantly higher precision in comparison to the two-dimensional data collected at 176 K [Takigawa et al. [(1966) Bull. Chem. Soc. Jpn, 39, 2369-2378]. The carboxyl group and indole ring system are planar, with maximum deviations of 0.002 (2) and 0.007 (2) Å, respectively, and make an angle of 70.17 (1)° with each other. The mol-ecules are arranged in double layers of carboxyl and amino groups parallel to the ab plane, stabilized by an extensive network of N-H⋯Br and O-H⋯Br hydrogen bonds. The polar layer is held together by a network of three N-H⋯Br hydrogen bonds and one O-H⋯Br hydrogen bond. In the non-polar layer, the indole rings are linked mainly by electrostatic N-H⋯C inter-actions between the polarized bond N-H (H is δ(+)) of the pyrrole unit and two of the ring C atoms (δ(-)) of the benzene rings of adjacent mol-ecules. The distances of these electrostatic inter-actions are 2.57 and 2.68 Å, respectively. C-H⋯O and C-H⋯π inter-actions are also present.

Related literature

For a previous determination of the crystal structure of the title compound, see: Takigawa et al. (1966 ▶). Study of crystal structures of amino acids and their complexes has provided information about aggregation and the effect of other mol­ecules on their inter­actions and mol­ecular properties, see: Vijayan (1988 ▶); Prasad & Vijayan (1993 ▶). For the structure of histidine hydro­chloride monohydrate, see: Takigawa et al. (1966 ▶). Donohue & Caron (1964 ▶). The structures of many amino acids with non-polar side chains feature a double-layered arrangement, see: Harding & Long (1968 ▶); Torii & Iitaka (1970 ▶, 1971 ▶, 1973 ▶).

Experimental

Crystal data

C11H13N2O2 +·Br−

M = 285.13

Monoclinic,

a = 7.6272 (3) Å

b = 5.3840 (2) Å

c = 14.4358 (5) Å

β = 100.688 (3)°

V = 582.52 (4) Å3

Z = 2

Mo Kα radiation

μ = 3.52 mm−1

T = 100 K

0.40 × 0.15 × 0.15 mm

Data collection

Oxford Xcalibur2 CCD diffractometer

Absorption correction: multi-scan (SCALE3 ABSPACK in CrysAlis RED; Oxford Diffraction, 2008 ▶) T min = 0.334, T max = 0.621

5749 measured reflections

2731 independent reflections

2507 reflections with I > 2σ(I)

R int = 0.024

Refinement

R[F 2 > 2σ(F 2)] = 0.027

wR(F 2) = 0.063

S = 1.01

2731 reflections

147 parameters

1 restraint

H-atom parameters constrained

Δρmax = 0.33 e Å−3

Δρmin = −1.14 e Å−3

Absolute structure: Flack (1983 ▶), 523 Freidel pairs

Flack parameter: 0.009 (9)

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809017322/at2781sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809017322/at2781Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C11H13N2O2+·Br−	F(000) = 288
Mr = 285.13	Dx = 1.626 Mg m−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 4434 reflections
a = 7.6272 (3) Å	θ = 3.8–31.9°
b = 5.3840 (2) Å	µ = 3.52 mm−1
c = 14.4358 (5) Å	T = 100 K
β = 100.688 (3)°	Needle, colourless
V = 582.52 (4) Å3	0.40 × 0.15 × 0.15 mm
Z = 2

Oxford Xcalibur2 CCD diffractometer	2731 independent reflections
Radiation source: Enhance (Mo) X-ray Source	2507 reflections with I > 2σ(I)
graphite	Rint = 0.024
Detector resolution: 8.4190 pixels mm-1	θmax = 32.0°, θmin = 4.1°
ω/2θ scans	h = −11→10
Absorption correction: multi-scan (SCALE3 ABSPACK in CrysAlis RED; Oxford Diffraction, 2008)	k = −6→7
Tmin = 0.334, Tmax = 0.621	l = −21→21
5749 measured reflections

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.027	H-atom parameters constrained
wR(F2) = 0.063	w = 1/[σ2(Fo2) + (0.0388P)2] where P = (Fo2 + 2Fc2)/3
S = 1.01	(Δ/σ)max < 0.001
2731 reflections	Δρmax = 0.33 e Å−3
147 parameters	Δρmin = −1.14 e Å−3
1 restraint	Absolute structure: Flack (1983), 523 Freidel pairs
Primary atom site location: structure-invariant direct methods	Flack parameter: 0.009 (9)

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 > σ(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.

	x	y	z	Uiso*/Ueq
C1	0.2755 (3)	0.4954 (5)	0.66336 (17)	0.0112 (4)
H6	0.4001	0.5280	0.6774	0.013*
C2	0.1920 (3)	0.3004 (4)	0.69909 (15)	0.0095 (5)
C3	0.0055 (3)	0.3213 (4)	0.65929 (15)	0.0086 (4)
C4	−0.1449 (3)	0.1811 (5)	0.66802 (15)	0.0111 (4)
H1	−0.1339	0.0367	0.7065	0.013*
C5	−0.3108 (3)	0.2569 (9)	0.61935 (14)	0.0141 (4)
H2	−0.4140	0.1638	0.6253	0.017*
C6	−0.3286 (3)	0.4686 (5)	0.56162 (17)	0.0141 (5)
H3	−0.4436	0.5159	0.5291	0.017*
C7	−0.1815 (3)	0.6103 (5)	0.55101 (17)	0.0125 (4)
H4	−0.1932	0.7530	0.5116	0.015*
C8	−0.0151 (3)	0.5338 (5)	0.60080 (16)	0.0103 (4)
C9	0.2770 (3)	0.0989 (5)	0.76424 (16)	0.0100 (4)
H7	0.3862	0.0421	0.7428	0.012*
H8	0.1939	−0.0438	0.7591	0.012*
C10	0.3269 (3)	0.1746 (5)	0.86847 (15)	0.0109 (4)
H9	0.3832	0.0280	0.9049	0.013*
C11	0.4583 (3)	0.3889 (5)	0.88531 (16)	0.0124 (5)
N1	0.1513 (3)	0.6363 (4)	0.60405 (14)	0.0120 (4)
H5	0.1746	0.7698	0.5733	0.014*
N2	0.1651 (2)	0.2443 (6)	0.90642 (12)	0.0142 (3)
H13	0.1107	0.3761	0.8735	0.021*
H11	0.1972	0.2860	0.9683	0.021*
H12	0.0885	0.1133	0.9006	0.021*
O1	0.4357 (3)	0.5748 (4)	0.92793 (13)	0.0166 (4)
O2	0.5974 (2)	0.3408 (4)	0.84628 (15)	0.0229 (4)
H10	0.6731	0.4547	0.8596	0.034*
Br1	0.90610 (3)	0.74408 (5)	0.873511 (13)	0.01394 (7)

	U11	U22	U33	U12	U13	U23
C1	0.0119 (10)	0.0122 (12)	0.0092 (10)	−0.0014 (9)	0.0012 (8)	−0.0008 (8)
C2	0.0108 (9)	0.0105 (14)	0.0072 (9)	0.0005 (7)	0.0017 (7)	−0.0011 (7)
C3	0.0107 (10)	0.0096 (10)	0.0051 (9)	0.0013 (7)	0.0001 (7)	−0.0008 (7)
C4	0.0132 (10)	0.0116 (11)	0.0080 (9)	0.0002 (8)	0.0005 (7)	0.0008 (7)
C5	0.0117 (9)	0.0175 (11)	0.0133 (9)	−0.0010 (17)	0.0028 (7)	−0.0037 (17)
C6	0.0122 (11)	0.0190 (13)	0.0104 (11)	0.0051 (9)	0.0002 (8)	0.0005 (9)
C7	0.0176 (11)	0.0114 (11)	0.0084 (10)	0.0043 (9)	0.0024 (8)	0.0010 (8)
C8	0.0150 (11)	0.0099 (10)	0.0063 (10)	−0.0006 (9)	0.0027 (8)	−0.0012 (8)
C9	0.0107 (10)	0.0092 (10)	0.0089 (10)	−0.0004 (8)	−0.0010 (8)	−0.0020 (8)
C10	0.0142 (11)	0.0095 (10)	0.0081 (10)	−0.0010 (8)	−0.0002 (7)	−0.0002 (8)
C11	0.0128 (10)	0.0127 (12)	0.0091 (10)	−0.0035 (9)	−0.0048 (8)	0.0010 (9)
N1	0.0172 (10)	0.0092 (10)	0.0095 (9)	−0.0020 (8)	0.0023 (7)	0.0019 (7)
N2	0.0194 (8)	0.0124 (8)	0.0120 (7)	−0.0064 (15)	0.0062 (6)	−0.0017 (14)
O1	0.0216 (9)	0.0114 (9)	0.0158 (9)	−0.0046 (7)	0.0009 (7)	−0.0030 (7)
O2	0.0124 (9)	0.0217 (10)	0.0354 (11)	−0.0078 (8)	0.0061 (8)	−0.0112 (9)
Br1	0.01610 (10)	0.01382 (11)	0.01214 (9)	−0.00518 (15)	0.00322 (6)	0.00128 (14)

C1—C2	1.377 (3)	C8—N1	1.377 (3)
C1—N1	1.381 (3)	C9—C10	1.537 (3)
C1—H6	0.9500	C9—H7	0.9900
C2—C3	1.436 (3)	C9—H8	0.9900
C2—C9	1.502 (3)	C10—N2	1.488 (3)
C3—C4	1.398 (3)	C10—C11	1.518 (3)
C3—C8	1.413 (3)	C10—H9	1.0000
C4—C5	1.390 (3)	C11—O1	1.204 (3)
C4—H1	0.9500	C11—O2	1.316 (3)
C5—C6	1.404 (5)	N1—H5	0.8800
C5—H2	0.9500	N2—H13	0.9100
C6—C7	1.389 (4)	N2—H11	0.9100
C6—H3	0.9500	N2—H12	0.9100
C7—C8	1.399 (3)	O2—H10	0.8400
C7—H4	0.9500
C2—C1—N1	109.8 (2)	C2—C9—H7	108.5
C2—C1—H6	125.1	C10—C9—H7	108.5
N1—C1—H6	125.1	C2—C9—H8	108.5
C1—C2—C3	106.5 (2)	C10—C9—H8	108.5
C1—C2—C9	127.5 (2)	H7—C9—H8	107.5
C3—C2—C9	126.0 (2)	N2—C10—C11	108.5 (2)
C4—C3—C8	119.2 (2)	N2—C10—C9	110.80 (18)
C4—C3—C2	133.6 (2)	C11—C10—C9	113.26 (19)
C8—C3—C2	107.1 (2)	N2—C10—H9	108.0
C5—C4—C3	118.8 (3)	C11—C10—H9	108.0
C5—C4—H1	120.6	C9—C10—H9	108.0
C3—C4—H1	120.6	O1—C11—O2	125.8 (2)
C4—C5—C6	121.1 (3)	O1—C11—C10	124.1 (2)
C4—C5—H2	119.4	O2—C11—C10	110.0 (2)
C6—C5—H2	119.4	C8—N1—C1	108.9 (2)
C7—C6—C5	121.4 (2)	C8—N1—H5	125.6
C7—C6—H3	119.3	C1—N1—H5	125.6
C5—C6—H3	119.3	C10—N2—H13	109.5
C6—C7—C8	117.1 (2)	C10—N2—H11	109.5
C6—C7—H4	121.4	H13—N2—H11	109.5
C8—C7—H4	121.4	C10—N2—H12	109.5
N1—C8—C7	129.9 (2)	H13—N2—H12	109.5
N1—C8—C3	107.7 (2)	H11—N2—H12	109.5
C7—C8—C3	122.4 (2)	C11—O2—H10	109.5
C2—C9—C10	114.9 (2)
N1—C1—C2—C3	0.3 (3)	C2—C3—C8—N1	0.6 (2)
N1—C1—C2—C9	178.4 (2)	C4—C3—C8—C7	0.1 (3)
C1—C2—C3—C4	179.8 (2)	C2—C3—C8—C7	−179.7 (2)
C9—C2—C3—C4	1.6 (4)	C1—C2—C9—C10	78.8 (3)
C1—C2—C3—C8	−0.5 (2)	C3—C2—C9—C10	−103.4 (3)
C9—C2—C3—C8	−178.7 (2)	C2—C9—C10—N2	62.4 (3)
C8—C3—C4—C5	−0.6 (3)	C2—C9—C10—C11	−59.8 (3)
C2—C3—C4—C5	179.1 (3)	N2—C10—C11—O1	4.3 (3)
C3—C4—C5—C6	0.6 (4)	C9—C10—C11—O1	127.8 (3)
C4—C5—C6—C7	−0.1 (4)	N2—C10—C11—O2	−175.31 (19)
C5—C6—C7—C8	−0.4 (4)	C9—C10—C11—O2	−51.8 (3)
C6—C7—C8—N1	−179.9 (2)	C7—C8—N1—C1	179.9 (2)
C6—C7—C8—C3	0.4 (3)	C3—C8—N1—C1	−0.4 (3)
C4—C3—C8—N1	−179.7 (2)	C2—C1—N1—C8	0.1 (3)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H4···Cg1i	0.95	2.66	3.494 (3)	146
N1—H5···Cg2i	0.88	2.72	3.406 (2)	136
N2—H11···Br1ii	0.91	2.56	3.3208 (17)	142
N2—H12···Br1iii	0.91	2.42	3.322 (3)	173
N2—H13···Br1iv	0.91	2.52	3.320 (3)	147
C4—H1···Br1iii	0.95	2.85	3.750 (2)	159
C10—H9···O1v	1.00	2.49	3.404 (3)	153
C10—H9···O1ii	1.00	2.56	3.199 (3)	121
O2—H10···Br1	0.84	2.34	3.173 (2)	169

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H4⋯Cg1i	0.95	2.66	3.494 (3)	146
N1—H5⋯Cg2i	0.88	2.72	3.406 (2)	136
N2—H11⋯Br1ii	0.91	2.56	3.3208 (17)	142
N2—H12⋯Br1iii	0.91	2.42	3.322 (3)	173
N2—H13⋯Br1iv	0.91	2.52	3.320 (3)	147
C4—H1⋯Br1iii	0.95	2.85	3.750 (2)	159
C10—H9⋯O1v	1.00	2.49	3.404 (3)	153
C10—H9⋯O1ii	1.00	2.56	3.199 (3)	121
O2—H10⋯Br1	0.84	2.34	3.173 (2)	169

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) . Cg1 is the centroid of the N1/C1–C3/C8 ring and Cg2 is the centroid of the C3–C8 ring.