L-Argininium trifluoro­acetate

In the title compound, C₆H₁₆N₄O₂⁺·C₂F₃O₂⁻, the amino acid exists as a zwitterionic argininium cation, with positively charged amino and guanidinium groups and a negatively charged carboxyl­ate group. The trifluoroacetic acid mol­ecule is deprotonated. The stoichiometry between the argininium ion and the trifluoro­acetate anion is 1:1. The aggregation of argininium cations and trifluoro­acetate anions is strikingly similar to those observed in the 1:2 stoichiometric analogue.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.060
• wR factor = 0.150
• Data-to-parameter ratio = 7.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.11
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C8
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.23
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5

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           25.03
           From the CIF: _reflns_number_total               1223
           Count of symmetry unique reflns         1236
           Completeness (_total/calc)             98.95%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

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

   0 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
   2 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97.

L-argininium trifluoroacetic acid

Crystal data

C6H15N4O2^+·C2F3O2^−	F(000) = 300
Mr = 288.24	Dx = 1.526 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1223 reflections
a = 10.5860 (6) Å	θ = 2–25°
b = 5.6880 (4) Å	µ = 0.15 mm^−1
c = 10.8780 (7) Å	T = 295 K
β = 106.770 (1)°	Block, colourless
V = 627.14 (7) Å^3	0.26 × 0.18 × 0.12 mm
Z = 2

Data collection

Nonius MACH3 four-circle diffractometer	1097 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.032
Graphite monochromator	θmax = 25.0°, θmin = 2.0°
ω scans	h = 0→12
Absorption correction: ψ scan (North et al., 1968)	k = −1→6
Tmin = 0.97, Tmax = 0.98	l = −12→12
1539 measured reflections	3 standard reflections every 60 min
1223 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.151	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.1263P)^2 + 0.0434P] where P = (Fo^2 + 2Fc^2)/3
1223 reflections	(Δ/σ)max < 0.001
172 parameters	Δρmax = 0.30 e Å^−3
1 restraint	Δρmin = −0.38 e Å^−3

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
O1	0.5373 (2)	0.2646 (5)	0.4198 (3)	0.0404 (7)
O2	0.7427 (3)	0.1263 (5)	0.4699 (3)	0.0409 (7)
N2	1.1220 (3)	0.4209 (7)	0.2830 (3)	0.0377 (8)
H2A	1.1841	0.4932	0.3388	0.045*
N3	1.2801 (3)	0.1560 (8)	0.2699 (3)	0.0438 (9)
H3C	1.3029	0.0285	0.2394	0.053*
H3D	1.3380	0.2366	0.3257	0.053*
C2	0.7108 (3)	0.5309 (7)	0.4195 (3)	0.0261 (7)
H2	0.7752	0.5755	0.5006	0.031*
C4	0.9141 (3)	0.4356 (8)	0.3449 (3)	0.0356 (8)
H4A	0.9639	0.4726	0.4326	0.043*
H4B	0.9034	0.2663	0.3380	0.043*
C1	0.6600 (3)	0.2876 (6)	0.4373 (3)	0.0267 (7)
C3	0.7786 (3)	0.5522 (7)	0.3138 (3)	0.0314 (8)
H3A	0.7883	0.7176	0.2968	0.038*
H3B	0.7221	0.4824	0.2359	0.038*
N4	1.0687 (3)	0.1024 (7)	0.1454 (3)	0.0429 (9)
H4C	0.9869	0.1429	0.1214	0.052*
H4D	1.0940	−0.0212	0.1136	0.052*
N1	0.5998 (3)	0.7046 (6)	0.3937 (3)	0.0318 (7)
H1A	0.6301	0.8472	0.3837	0.048*
H1B	0.5658	0.7062	0.4596	0.048*
H1C	0.5376	0.6637	0.3226	0.048*
C5	0.9896 (3)	0.5197 (8)	0.2539 (3)	0.0378 (9)
H5A	0.9406	0.4773	0.1668	0.045*
H5B	0.9959	0.6898	0.2582	0.045*
C6	1.1545 (3)	0.2290 (8)	0.2305 (3)	0.0325 (8)
F2	0.2764 (4)	0.2887 (6)	−0.0143 (3)	0.0841 (12)
F1	0.3384 (4)	0.5534 (7)	−0.1197 (3)	0.0797 (10)
O3	0.3711 (3)	0.7280 (8)	0.1804 (3)	0.0569 (9)
O4	0.1828 (3)	0.7411 (8)	0.0229 (3)	0.0599 (9)
F3	0.4711 (3)	0.4273 (10)	0.0537 (4)	0.1064 (16)
C7	0.2965 (3)	0.6685 (8)	0.0751 (3)	0.0398 (9)
C8	0.3464 (4)	0.4837 (9)	−0.0010 (4)	0.0486 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0213 (11)	0.0461 (17)	0.0551 (14)	−0.0060 (12)	0.0130 (10)	0.0056 (13)
O2	0.0286 (12)	0.0350 (15)	0.0620 (15)	0.0038 (11)	0.0175 (11)	0.0113 (12)
N2	0.0190 (13)	0.053 (2)	0.0416 (14)	−0.0073 (15)	0.0101 (11)	−0.0080 (15)
N3	0.0192 (13)	0.067 (2)	0.0433 (14)	0.0035 (16)	0.0052 (11)	−0.0076 (17)
C2	0.0143 (13)	0.0337 (18)	0.0303 (14)	0.0045 (14)	0.0064 (11)	0.0005 (14)
C4	0.0215 (16)	0.048 (2)	0.0418 (17)	0.0053 (17)	0.0163 (13)	0.0070 (18)
C1	0.0204 (15)	0.0336 (19)	0.0274 (14)	0.0014 (14)	0.0090 (12)	0.0014 (13)
C3	0.0250 (16)	0.037 (2)	0.0355 (14)	0.0037 (16)	0.0133 (12)	0.0063 (15)
N4	0.0224 (13)	0.057 (2)	0.0455 (15)	0.0024 (15)	0.0031 (12)	−0.0084 (16)
N1	0.0220 (13)	0.0335 (17)	0.0418 (15)	0.0020 (13)	0.0122 (11)	0.0012 (13)
C5	0.0281 (16)	0.046 (2)	0.0460 (18)	0.0052 (18)	0.0208 (14)	0.0049 (18)
C6	0.0200 (15)	0.048 (2)	0.0304 (14)	−0.0039 (16)	0.0095 (12)	0.0035 (16)
F2	0.131 (3)	0.052 (2)	0.085 (2)	−0.027 (2)	0.056 (2)	−0.0171 (17)
F1	0.110 (3)	0.081 (2)	0.0637 (15)	−0.013 (2)	0.0491 (16)	−0.0042 (17)
O3	0.0356 (14)	0.075 (2)	0.0485 (14)	0.0120 (16)	−0.0060 (11)	−0.0151 (17)
O4	0.0303 (14)	0.073 (2)	0.0636 (17)	0.0088 (16)	−0.0073 (12)	−0.015 (2)
F3	0.063 (2)	0.125 (4)	0.116 (3)	0.045 (2)	0.0026 (18)	−0.044 (3)
C7	0.0272 (17)	0.046 (2)	0.0405 (17)	−0.0005 (18)	0.0015 (13)	−0.0007 (17)
C8	0.046 (2)	0.045 (2)	0.053 (2)	0.000 (2)	0.0121 (18)	−0.0016 (19)

Geometric parameters (Å, º)

O1—C1	1.264 (4)	C3—H3A	0.9700
O2—C1	1.247 (4)	C3—H3B	0.9700
N2—C6	1.322 (6)	N4—C6	1.310 (5)
N2—C5	1.458 (4)	N4—H4C	0.8600
N2—H2A	0.8600	N4—H4D	0.8600
N3—C6	1.340 (5)	N1—H1A	0.8900
N3—H3C	0.8600	N1—H1B	0.8900
N3—H3D	0.8600	N1—H1C	0.8900
C2—N1	1.498 (4)	C5—H5A	0.9700
C2—C1	1.517 (5)	C5—H5B	0.9700
C2—C3	1.525 (4)	F2—C8	1.319 (6)
C2—H2	0.9800	F1—C8	1.330 (6)
C4—C5	1.518 (5)	O3—C7	1.236 (5)
C4—C3	1.526 (5)	O4—C7	1.244 (5)
C4—H4A	0.9700	F3—C8	1.321 (5)
C4—H4B	0.9700	C7—C8	1.524 (6)
C6—N2—C5	125.3 (3)	C6—N4—H4C	120.0
C6—N2—H2A	117.3	C6—N4—H4D	120.0
C5—N2—H2A	117.3	H4C—N4—H4D	120.0
C6—N3—H3C	120.0	C2—N1—H1A	109.5
C6—N3—H3D	120.0	C2—N1—H1B	109.5
H3C—N3—H3D	120.0	H1A—N1—H1B	109.5
N1—C2—C1	109.7 (2)	C2—N1—H1C	109.5
N1—C2—C3	108.7 (3)	H1A—N1—H1C	109.5
C1—C2—C3	115.5 (3)	H1B—N1—H1C	109.5
N1—C2—H2	107.5	N2—C5—C4	113.0 (3)
C1—C2—H2	107.5	N2—C5—H5A	109.0
C3—C2—H2	107.5	C4—C5—H5A	109.0
C5—C4—C3	110.9 (3)	N2—C5—H5B	109.0
C5—C4—H4A	109.5	C4—C5—H5B	109.0
C3—C4—H4A	109.5	H5A—C5—H5B	107.8
C5—C4—H4B	109.5	N4—C6—N2	123.0 (3)
C3—C4—H4B	109.5	N4—C6—N3	118.6 (4)
H4A—C4—H4B	108.1	N2—C6—N3	118.4 (3)
O2—C1—O1	125.0 (3)	O3—C7—O4	127.4 (4)
O2—C1—C2	117.5 (3)	O3—C7—C8	117.6 (4)
O1—C1—C2	117.5 (3)	O4—C7—C8	115.0 (3)
C2—C3—C4	114.5 (3)	F2—C8—F3	107.6 (5)
C2—C3—H3A	108.6	F2—C8—F1	105.5 (4)
C4—C3—H3A	108.6	F3—C8—F1	106.6 (4)
C2—C3—H3B	108.6	F2—C8—C7	111.6 (4)
C4—C3—H3B	108.6	F3—C8—C7	112.4 (4)
H3A—C3—H3B	107.6	F1—C8—C7	112.8 (4)
N1—C2—C1—O2	−174.3 (3)	C5—N2—C6—N4	−0.8 (6)
C3—C2—C1—O2	62.5 (4)	C5—N2—C6—N3	−178.1 (3)
N1—C2—C1—O1	4.7 (4)	O3—C7—C8—F2	115.2 (5)
C3—C2—C1—O1	−118.6 (3)	O4—C7—C8—F2	−64.3 (6)
N1—C2—C3—C4	164.5 (3)	O3—C7—C8—F3	−5.7 (7)
C1—C2—C3—C4	−71.7 (4)	O4—C7—C8—F3	174.7 (5)
C5—C4—C3—C2	−164.5 (3)	O3—C7—C8—F1	−126.3 (5)
C6—N2—C5—C4	93.6 (4)	O4—C7—C8—F1	54.2 (6)
C3—C4—C5—N2	177.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O2^i	0.89	2.04	2.829 (4)	147
N1—H1B···O1^ii	0.89	1.96	2.835 (4)	167
N1—H1C···O3	0.89	2.01	2.832 (4)	152
N2—H2A···O2^iii	0.86	2.14	2.902 (4)	148
N3—H3C···O3^iv	0.86	2.03	2.888 (6)	175
N3—H3D···O1^v	0.86	2.07	2.808 (4)	144
N4—H4C···O4^vi	0.86	2.09	2.872 (4)	151
N4—H4D···O4^iv	0.86	2.05	2.896 (5)	166
C5—H5A···O4^vi	0.97	2.49	3.426 (5)	161

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