A triclinic polymorph of L-argininium chloride

The title compound, C₆H₁₅N₄O₂⁺·Cl^-, crystallizes in the triclinic system with two crystallographically independent argininium residues and two chloride ions in the P1 unit cell. In an earlier study, the structure of L-arginine chloride [Mazumdar et al. (1969). Z. Kristallogr. 130, 328-339] was determined in the monoclinic space group P2₁. In our work, the side-chain conformation has an all-trans form in one of the residues, whereas in the other residue, it is in the gauche I-trans-trans-trans form. All the N atoms, carboxyl­ate groups and chloride ions are involved in a hydrogen-bonding network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.042
• wR factor = 0.136
• Data-to-parameter ratio = 28.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           35.87
         From the CIF: _reflns_number_total               6750
         Count of symmetry unique reflns         4571
         Completeness (_total/calc)            147.67%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured      2179
         Fraction of Friedel pairs measured     0.477
         Are heavy atom types Z>Si present          yes
          WARNING: Large fraction of Friedel related reflns may
                   be needed to determine absolute structure

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Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1999); software used to prepare material for publication: SHELXL97.

L-argininium chloride

Crystal data

C6H15N4O2^+·Cl^−	Z = 2
Mr = 210.67	F(000) = 224
Triclinic, P1	Dx = 1.438 Mg m^−3 Dm = 1.435 Mg m^−3 Dm measured by flotation in carbon tetrachloride and xylene
a = 5.1263 (8) Å	Mo Kα radiation, λ = 0.71074 Å
b = 9.461 (1) Å	Cell parameters from 9359 reflections
c = 10.322 (2) Å	θ = 2.4–35.3°
α = 88.138 (5)°	µ = 0.37 mm^−1
β = 76.447 (4)°	T = 293 K
γ = 89.745 (5)°	Block, colorless
V = 486.37 (13) Å^3	0.8 × 0.5 × 0.5 mm

Data collection

Bruker SMART CCD diffractometer	6750 independent reflections
Radiation source: fine-focus sealed tube	6192 reflections with I > \2s(I)
Graphite monochromator	Rint = 0.024
Detector resolution: 8.33 pixels mm^-1	θmax = 35.9°, θmin = 2.0°
ω scans	h = −8→8
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −15→15
Tmin = 0.74, Tmax = 0.83	l = −16→16
10067 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.136	w = 1/[σ^2(Fo^2) + (0.1P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
6750 reflections	Δρmax = 0.48 e Å^−3
235 parameters	Δρmin = −0.28 e Å^−3
3 restraints	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.12 (4)

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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1A	0.3939 (2)	0.57357 (12)	1.01021 (12)	0.0255 (2)
O1B	0.0035 (2)	0.65441 (14)	0.97668 (14)	0.0292 (2)
C11	0.2490 (3)	0.66502 (14)	0.96937 (13)	0.0186 (2)
C12	0.3919 (3)	0.79894 (14)	0.89989 (14)	0.0199 (2)
H12	0.2567	0.8697	0.8907	0.024*
N11	0.5673 (3)	0.85735 (14)	0.98226 (14)	0.0250 (2)
H11A	0.4687	0.8751	1.0632	0.038*
H11B	0.6440	0.9371	0.9436	0.038*
H11C	0.6938	0.7947	0.9891	0.038*
C13	0.5659 (3)	0.76959 (18)	0.76201 (15)	0.0271 (3)
H13A	0.6317	0.8585	0.7170	0.032*
H13B	0.7199	0.7138	0.7716	0.032*
C14	0.4115 (4)	0.69091 (19)	0.67734 (16)	0.0288 (3)
H14A	0.2377	0.7350	0.6846	0.035*
H14B	0.3815	0.5941	0.7112	0.035*
N12	0.4039 (3)	0.60647 (18)	0.46169 (14)	0.0321 (3)
H12A	0.2622	0.5654	0.5087	0.039*
C15	0.5609 (4)	0.6909 (2)	0.53119 (16)	0.0290 (3)
H15A	0.5805	0.7867	0.4939	0.035*
H15B	0.7382	0.6505	0.5225	0.035*
C16	0.4623 (3)	0.58825 (17)	0.33234 (16)	0.0251 (3)
N13	0.3089 (4)	0.50008 (19)	0.28236 (16)	0.0347 (3)
H13C	0.1758	0.4569	0.3347	0.042*
H13D	0.3439	0.4868	0.1980	0.042*
N14	0.6746 (4)	0.65059 (18)	0.25175 (15)	0.0326 (3)
H14C	0.7771	0.7042	0.2840	0.039*
H14D	0.7092	0.6373	0.1674	0.039*
O2A	0.9294 (3)	0.07978 (13)	−0.15308 (13)	0.0283 (2)
O2B	1.3220 (2)	0.13899 (14)	−0.11107 (14)	0.0295 (2)
C21	1.0806 (3)	0.16165 (14)	−0.11120 (14)	0.0207 (2)
C22	0.9677 (3)	0.30346 (14)	−0.05506 (14)	0.0208 (2)
H22	1.1041	0.3763	−0.0891	0.025*
N21	0.7240 (3)	0.34155 (14)	−0.10402 (14)	0.0242 (2)
H21A	0.7640	0.3423	−0.1927	0.036*
H21B	0.6675	0.4269	−0.0762	0.036*
H21C	0.5951	0.2782	−0.0724	0.036*
C23	0.9130 (3)	0.30002 (16)	0.09677 (15)	0.0247 (3)
H23A	0.8522	0.3929	0.1277	0.030*
H23B	1.0807	0.2816	0.1223	0.030*
C24	0.7064 (4)	0.19070 (19)	0.16861 (16)	0.0280 (3)
H24A	0.5341	0.2110	0.1486	0.034*
H24B	0.7617	0.0972	0.1372	0.034*
C25	0.6789 (4)	0.19318 (18)	0.31791 (15)	0.0265 (3)
H25A	0.8431	0.1595	0.3395	0.032*
H25B	0.6478	0.2892	0.3479	0.032*
N22	0.4547 (3)	0.10299 (18)	0.38483 (14)	0.0324 (3)
H22A	0.3686	0.0586	0.3364	0.039*
C26	0.3766 (3)	0.08561 (17)	0.51556 (16)	0.0276 (3)
N23	0.5095 (3)	0.14250 (19)	0.59558 (16)	0.0347 (3)
H23C	0.6508	0.1924	0.5629	0.042*
H23D	0.4549	0.1298	0.6805	0.042*
N24	0.1654 (4)	0.0006 (2)	0.56862 (18)	0.0363 (3)
H24C	0.1196	−0.0155	0.6534	0.044*
H24D	0.0765	−0.0373	0.5177	0.044*
Cl1	0.11711 (9)	0.89352 (5)	0.25378 (5)	0.04018 (12)
Cl2	0.94094 (10)	0.38732 (5)	−0.41371 (5)	0.04289 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1A	0.0264 (5)	0.0211 (5)	0.0278 (5)	−0.0003 (4)	−0.0043 (4)	0.0027 (4)
O1B	0.0195 (5)	0.0330 (6)	0.0334 (6)	−0.0059 (4)	−0.0030 (4)	0.0019 (4)
C11	0.0186 (5)	0.0193 (5)	0.0168 (5)	−0.0027 (4)	−0.0011 (4)	−0.0026 (4)
C12	0.0210 (6)	0.0168 (5)	0.0214 (5)	−0.0026 (4)	−0.0037 (4)	0.0000 (4)
N11	0.0283 (6)	0.0225 (5)	0.0233 (5)	−0.0083 (4)	−0.0037 (5)	−0.0020 (4)
C13	0.0282 (7)	0.0339 (7)	0.0172 (5)	−0.0087 (5)	−0.0011 (5)	−0.0008 (5)
C14	0.0295 (7)	0.0367 (8)	0.0186 (6)	−0.0106 (6)	−0.0025 (5)	−0.0012 (5)
N12	0.0345 (7)	0.0425 (8)	0.0179 (6)	−0.0135 (6)	−0.0028 (5)	−0.0022 (5)
C15	0.0296 (7)	0.0384 (8)	0.0168 (6)	−0.0081 (6)	−0.0009 (5)	−0.0029 (5)
C16	0.0266 (7)	0.0281 (7)	0.0199 (6)	−0.0003 (5)	−0.0040 (5)	−0.0010 (5)
N13	0.0425 (9)	0.0391 (8)	0.0232 (6)	−0.0096 (6)	−0.0089 (6)	−0.0016 (5)
N14	0.0357 (7)	0.0390 (8)	0.0195 (6)	−0.0055 (6)	0.0009 (5)	−0.0009 (5)
O2A	0.0251 (5)	0.0240 (5)	0.0339 (6)	−0.0062 (4)	−0.0022 (4)	−0.0069 (4)
O2B	0.0203 (5)	0.0300 (6)	0.0372 (6)	0.0016 (4)	−0.0041 (4)	−0.0048 (5)
C21	0.0213 (6)	0.0182 (5)	0.0200 (5)	−0.0028 (4)	0.0005 (4)	−0.0006 (4)
C22	0.0206 (6)	0.0178 (5)	0.0221 (6)	−0.0022 (4)	−0.0009 (4)	−0.0017 (4)
N21	0.0261 (6)	0.0210 (5)	0.0240 (6)	0.0011 (4)	−0.0030 (4)	−0.0003 (4)
C23	0.0253 (6)	0.0263 (6)	0.0213 (6)	−0.0031 (5)	−0.0029 (5)	−0.0050 (5)
C24	0.0296 (7)	0.0354 (8)	0.0183 (6)	−0.0080 (6)	−0.0045 (5)	0.0005 (5)
C25	0.0305 (7)	0.0302 (7)	0.0171 (6)	−0.0030 (6)	−0.0021 (5)	−0.0002 (5)
N22	0.0334 (7)	0.0415 (8)	0.0203 (6)	−0.0113 (6)	−0.0023 (5)	−0.0013 (5)
C26	0.0283 (7)	0.0284 (7)	0.0234 (7)	−0.0020 (6)	−0.0004 (5)	−0.0001 (5)
N23	0.0347 (8)	0.0464 (9)	0.0205 (6)	−0.0100 (6)	−0.0012 (5)	−0.0022 (5)
N24	0.0350 (8)	0.0404 (8)	0.0295 (7)	−0.0109 (6)	0.0008 (6)	0.0001 (6)
Cl1	0.0359 (2)	0.0391 (2)	0.0421 (2)	−0.00693 (16)	−0.00051 (17)	−0.01191 (17)
Cl2	0.0486 (3)	0.0438 (2)	0.0326 (2)	−0.0183 (2)	−0.00280 (18)	0.00565 (17)

Geometric parameters (Å, º)

O1A—C11	1.2631 (18)	O2A—C21	1.2536 (18)
O1B—C11	1.2477 (18)	O2B—C21	1.2555 (19)
C11—C12	1.5359 (19)	C21—C22	1.5353 (19)
C12—N11	1.4932 (19)	C22—N21	1.492 (2)
C12—C13	1.525 (2)	C22—C23	1.525 (2)
C13—C14	1.522 (2)	C23—C24	1.527 (2)
C14—C15	1.523 (2)	C24—C25	1.515 (2)
N12—C16	1.315 (2)	C25—N22	1.457 (2)
N12—C15	1.454 (2)	N22—C26	1.319 (2)
C16—N14	1.332 (2)	C26—N23	1.316 (2)
C16—N13	1.343 (2)	C26—N24	1.349 (2)
O1B—C11—O1A	126.02 (14)	O2A—C21—O2B	125.77 (14)
O1B—C11—C12	117.37 (13)	O2A—C21—C22	118.67 (13)
O1A—C11—C12	116.57 (12)	O2B—C21—C22	115.55 (13)
N11—C12—C13	108.31 (12)	N21—C22—C23	112.22 (12)
N11—C12—C11	109.70 (11)	N21—C22—C21	110.15 (12)
C13—C12—C11	112.06 (11)	C23—C22—C21	111.07 (12)
C14—C13—C12	111.90 (13)	C22—C23—C24	115.50 (12)
C13—C14—C15	112.02 (14)	C25—C24—C23	110.48 (13)
C16—N12—C15	124.93 (15)	N22—C25—C24	109.21 (14)
N12—C15—C14	107.30 (14)	C26—N22—C25	123.65 (15)
N12—C16—N14	121.49 (16)	N23—C26—N22	121.56 (16)
N12—C16—N13	118.61 (15)	N23—C26—N24	118.86 (16)
N14—C16—N13	119.85 (15)	N22—C26—N24	119.45 (17)
O1B—C11—C12—N11	133.61 (14)	O2A—C21—C22—N21	−20.19 (18)
O1A—C11—C12—N11	−48.54 (16)	O2B—C21—C22—N21	159.50 (13)
O1B—C11—C12—C13	−106.05 (16)	O2A—C21—C22—C23	104.77 (16)
O1A—C11—C12—C13	71.80 (16)	O2B—C21—C22—C23	−75.54 (16)
N11—C12—C13—C14	172.10 (14)	N21—C22—C23—C24	62.31 (18)
C11—C12—C13—C14	50.95 (18)	C21—C22—C23—C24	−61.48 (18)
C12—C13—C14—C15	166.95 (15)	C22—C23—C24—C25	177.49 (14)
C16—N12—C15—C14	176.27 (18)	C23—C24—C25—N22	171.95 (15)
C13—C14—C15—N12	176.72 (16)	C24—C25—N22—C26	−178.56 (17)
C15—N12—C16—N14	−1.5 (3)	C25—N22—C26—N23	−4.6 (3)
C15—N12—C16—N13	175.79 (18)	C25—N22—C26—N24	179.52 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N11—H11A···Cl1^i	0.89	2.35	3.213 (2)	164
N11—H11B···O2A^ii	0.89	2.05	2.907 (2)	161
N11—H11C···O1B^iii	0.89	2.05	2.932 (2)	172
N12—H12A···Cl2^iv	0.86	2.35	3.166 (2)	159
N13—H13C···Cl2^iv	0.86	2.66	3.401 (2)	146
N13—H13D···O1A^v	0.86	2.04	2.805 (2)	148
N14—H14C···Cl1^iii	0.86	2.47	3.240 (2)	150
N14—H14D···O1B^vi	0.86	2.18	2.942 (2)	147
N21—H21A···Cl2	0.89	2.28	3.145 (2)	166
N21—H21B···O1A^v	0.89	2.04	2.876 (2)	156
N21—H21C···O2B^vii	0.89	2.04	2.835 (2)	148
N22—H22A···Cl1^viii	0.86	2.33	3.171 (2)	164
N23—H23C···Cl2^i	0.86	2.43	3.193 (2)	149
N23—H23D···O2B^iv	0.86	2.10	2.953 (2)	170
N24—H24C···O2A^iv	0.86	2.22	2.963 (2)	144
N24—H24D···Cl1^viii	0.86	2.78	3.499 (2)	142

Symmetry codes: (i) x, y, z+1; (ii) x, y+1, z+1; (iii) x+1, y, z; (iv) x−1, y, z+1; (v) x, y, z−1; (vi) x+1, y, z−1; (vii) x−1, y, z; (viii) x, y−1, z.