(2,4,6-Trinitro­phen­yl)guanidine

Smith, G.; Wermuth, U.D.; White, J.M.

doi:10.1107/S1600536807038068

(2,4,6-Trinitrophenyl)guanidine

(2,4,6-Trinitrophenyl)guanidine (picrylguanidine), C₇H₆N₆O₆, from the reaction of picrylsulfonic acid with guanidine carbonate, forms a three-dimensional framework structure through extensive hydrogen-bonding interactions, extending the centrosymmetric cyclic R₂²(16) dimer association which includes duplex R₂²(8) guanidine N—H

O_nitro interactions. The guanidine substituent chain has an endo [Ph—N=C(NH₂)₂] bond sequence rather than the less sterically encumbered exo [Ph—NH—C=NH(NH₂)] sequence of the tautomeric form. As a result, there is significant bond-angle distortion about C(—N=) of the aromatic ring.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807038068/bt2462sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807038068/bt2462Isup2.hkl Contains datablock I

CCDC reference: 660251

checkCIF report

Key indicators

Single-crystal X-ray study
T = 130 K
Mean (C-C) = 0.003 Å
R factor = 0.038
wR factor = 0.083
Data-to-parameter ratio = 9.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       9.25
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O42    -   N4      ..       5.18 su
PLAT430_ALERT_2_C Short Inter D...A Contact  O21    ..  O62     ..       2.89 Ang.
PLAT430_ALERT_2_C Short Inter D...A Contact  O22    ..  O22     ..       2.87 Ang.

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 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

2,4,6-trinitrobenzenesulfonic acid (picrylsulfonic acid) is a very strong acid which is capable of protonating water, such as is found in the crystalline 'tetrahydrate', which has the formula C₆H₂N₃O₉S^-. H₅O₂⁺. 2H₂O [Lundgren, 1972 (X-ray); Lundgren & Tellgren, 1974 (neutron)]. It will therefore readily protonate most Lewis bases, e.g. the 1:1 anhydrous salts with guanidine (Russell & Ward, 1997) and quinoline (Smith et al., 2006), and the adduct 2-carboxyquinolinium-picrylsulfonate-quinoline-2-carboxylic acid (1/1/1) (Smith et al., 2007). However, certain Lewis base types are capable of displacing the sulfonic acid substituent group (or chloride in the case of picryl chloride) to give amino addition compounds, such as with the three isomeric aminobenzoic acids (Crocker & Matthews, 1911) and with amino acids and proteins (Goldfarb, 1966). The structure of the 4-aminobenzoic acid compound 4-(2,4,6-trinitrophenylanilino)benzoic acid (Smith et al., 2007) is one of very few of this type which have been determined.

The 1:1 stoichiometric reaction of picrylsulfonic acid with guanidine carbonate in methanol was expected to give the previously reported proton-transfer compound guanidinium 2,4,6-trinitrobenzenesulfonate (Russell & Ward, 1997). However, the title compound, the addition compound (2,4,6-trinitrophenyl)guanidine C₇H₆N₆O₆ was formed as the only reaction product and the structure is reported here.

The title compound (Fig. 1) is found to have the endo [Ph–N═ C(NH₂)₂] bond sequence in the guanidine substituent chain rather than the sterically favoured Ph–NH–C═NH(NH₂) sequence of the tautomeric form of picrylguanidine (C·A. registry number 134282–41-1), which has the double bond exo. The bond arrangement with the double bond endo results in significant distortion in the aromatic ring angles associated with the C1 guanidine substituent group [C2–C1–N1, 128.4 (2) °; C6–C1–N1, 119.56 (19) °; C2–C1–C6, 111.81 (17) °]. The plane of the guanidine double bond is also twisted [torsion angle C1–N1–C71–N72, 151.3 (2) °]. As expected, the nitro groups of the picryl moiety ortho to the guanidine substituent are rotated out of the plane of the benzene ring [torsion angles C1–C2–N2–O22, 140.4 (2) Å; C1–C6–N6–O61, 136.2 (2) °], while the para-related group is essentially coplanar [C3–C4–N4–O42, -172.1 (2) °].

In the packing of the molecules in the unit cell, all guanidine protons give hydrogen-bonding associations with nitro-O acceptors (Table 1). The basic intermolecular interaction provides a centrosymmetric cyclic R₂²(16) dimer unit (Fig. 2) which incorporates duplex cyclic R₂²(8) guanidine N–H···O_nitro group associations [N71,N72···O41ⁱⁱ,O42ⁱⁱ: symmetry code; (ii) -x + 1, -y, -z + 1]. The overall result is a three-dimensional framework structure. (Fig. 3).

Related literature top

For related literature, see: Crocker & Matthews (1911); Goldfarb (1966); Lundgren (1972); Lundgren & Tellgren (1974); Russell & Ward (1997); Smith et al. (2006, 2007).

Experimental top

The title compound was synthesized by heating together 1 mmol quantities of 2,4,6-trinitrobenzenesulfonic acid (picrylsulfonic acid) and guanidine carbonate in 50 ml of methanol under reflux for 10 minutes. This reaction is analogous to the reaction of picryl chloride with the isomeric aminobenzoic acids (Crocker & Matthews, 1911) to give the picrylaminobenzoic acids. After concentration to ca 30 ml, partial room temperature evaporation of the hot-filtered solution gave a small quantity of pale yellow short crystal prisms of (I).

Structure description top

For related literature, see: Crocker & Matthews (1911); Goldfarb (1966); Lundgren (1972); Lundgren & Tellgren (1974); Russell & Ward (1997); Smith et al. (2006, 2007).

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON.

Figures top

	Fig. 1. Molecular configuration and atom naming scheme (I). Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The cyclic R₂²(16) hydrogen-bonded dimer incorporating duplex R₂²(8) N–H···O_nitro associations between centrosymmetrically related molecule pairs in the structure of (I), together with other extending interactions shown as dashed lines. For symmetry codes, see Table 1.
	Fig. 3. The three-dimensional framework structure of (I) viewed down the a cell direction.

(2,4,6-Trinitrophenyl)guanidine top

Crystal data top

C₇H₆N₆O₆	Z = 2
M_r = 270.18	F(000) = 276
Triclinic, P1	D_x = 1.794 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.6596 (10) Å	Cell parameters from 870 reflections
b = 7.7316 (10) Å	θ = 2.4–26.8°
c = 9.0411 (12) Å	µ = 0.16 mm⁻¹
α = 104.045 (3)°	T = 130 K
β = 95.004 (2)°	Block, pale yellow
γ = 103.121 (2)°	0.15 × 0.10 × 0.10 mm
V = 500.08 (11) Å³

Data collection top

Bruker CCD area-detector diffractometer	1344 reflections with I > 2σ(I)
Radiation source: sealed tube	R_int = 0.055
Graphite monochromator	θ_max = 25.0°, θ_min = 2.4°
φ and ω scans	h = −9→9
2614 measured reflections	k = −8→9
1739 independent reflections	l = −9→10

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.083	H atoms treated by a mixture of independent and constrained refinement
S = 0.92	w = 1/[σ²(F_o²) + (0.0265P)²] where P = (F_o² + 2F_c²)/3
1739 reflections	(Δ/σ)_max < 0.001
188 parameters	Δρ_max = 0.22 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₇H₆N₆O₆	γ = 103.121 (2)°
M_r = 270.18	V = 500.08 (11) Å³
Triclinic, P1	Z = 2
a = 7.6596 (10) Å	Mo Kα radiation
b = 7.7316 (10) Å	µ = 0.16 mm⁻¹
c = 9.0411 (12) Å	T = 130 K
α = 104.045 (3)°	0.15 × 0.10 × 0.10 mm
β = 95.004 (2)°

Data collection top

Bruker CCD area-detector diffractometer	1344 reflections with I > 2σ(I)
2614 measured reflections	R_int = 0.055
1739 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	0 restraints
wR(F²) = 0.083	H atoms treated by a mixture of independent and constrained refinement
S = 0.92	Δρ_max = 0.22 e Å⁻³
1739 reflections	Δρ_min = −0.21 e Å⁻³
188 parameters

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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 (Å²) top

	x	y	z	U_iso*/U_eq
O21	0.55099 (19)	0.2258 (2)	0.77212 (16)	0.0256 (5)
O22	0.5482 (2)	−0.0210 (2)	0.84817 (16)	0.0266 (5)
O41	1.0096 (2)	0.1267 (2)	1.29934 (15)	0.0252 (6)
O42	1.2715 (2)	0.3153 (2)	1.30851 (16)	0.0257 (5)
O61	1.3738 (2)	0.5820 (2)	0.86527 (16)	0.0238 (5)
O62	1.2606 (2)	0.3618 (2)	0.65498 (16)	0.0230 (5)
N1	0.8963 (2)	0.3241 (2)	0.66327 (19)	0.0188 (6)
N2	0.6276 (2)	0.1290 (3)	0.83048 (19)	0.0195 (6)
N4	1.1174 (3)	0.2305 (2)	1.24375 (19)	0.0198 (6)
N6	1.2622 (2)	0.4378 (2)	0.79090 (19)	0.0182 (6)
N71	0.7296 (3)	0.0290 (3)	0.5177 (2)	0.0202 (7)
N72	0.6838 (3)	0.2908 (3)	0.4587 (2)	0.0246 (7)
C1	0.9402 (3)	0.2847 (3)	0.7955 (2)	0.0170 (7)
C2	0.8224 (3)	0.1947 (3)	0.8841 (2)	0.0167 (7)
C3	0.8779 (3)	0.1727 (3)	1.0261 (2)	0.0175 (7)
C4	1.0577 (3)	0.2486 (3)	1.0925 (2)	0.0160 (7)
C5	1.1831 (3)	0.3402 (3)	1.0166 (2)	0.0176 (7)
C6	1.1241 (3)	0.3516 (3)	0.8732 (2)	0.0155 (7)
C7	0.7699 (3)	0.2148 (3)	0.5494 (2)	0.0187 (7)
H3	0.79440	0.10670	1.07740	0.0210*
H5	1.30590	0.39310	1.06320	0.0210*
H71A	0.810 (3)	−0.016 (3)	0.553 (2)	0.033 (8)*
H71B	0.658 (3)	−0.040 (3)	0.431 (3)	0.033 (7)*
H72A	0.694 (3)	0.414 (4)	0.486 (3)	0.041 (8)*
H72B	0.612 (3)	0.231 (3)	0.382 (2)	0.015 (6)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O21	0.0228 (9)	0.0305 (10)	0.0241 (9)	0.0108 (8)	−0.0001 (7)	0.0059 (7)
O22	0.0240 (9)	0.0245 (9)	0.0258 (9)	−0.0042 (7)	0.0026 (7)	0.0066 (7)
O41	0.0292 (10)	0.0291 (10)	0.0230 (9)	0.0093 (8)	0.0092 (7)	0.0141 (7)
O42	0.0211 (9)	0.0325 (10)	0.0204 (9)	0.0054 (8)	−0.0037 (7)	0.0050 (7)
O61	0.0212 (9)	0.0190 (9)	0.0266 (9)	−0.0002 (7)	0.0022 (7)	0.0032 (7)
O62	0.0282 (9)	0.0250 (9)	0.0171 (8)	0.0093 (7)	0.0070 (7)	0.0047 (7)
N1	0.0189 (10)	0.0173 (10)	0.0181 (10)	0.0016 (8)	−0.0020 (8)	0.0056 (8)
N2	0.0201 (10)	0.0221 (11)	0.0146 (10)	0.0051 (9)	0.0025 (8)	0.0021 (8)
N4	0.0243 (11)	0.0198 (10)	0.0185 (10)	0.0113 (9)	0.0043 (9)	0.0053 (8)
N6	0.0175 (10)	0.0200 (11)	0.0194 (10)	0.0078 (9)	0.0028 (8)	0.0070 (8)
N71	0.0218 (12)	0.0192 (11)	0.0176 (11)	0.0041 (9)	−0.0024 (9)	0.0040 (9)
N72	0.0289 (12)	0.0200 (12)	0.0206 (12)	0.0033 (10)	−0.0075 (10)	0.0042 (10)
C1	0.0222 (13)	0.0123 (11)	0.0158 (11)	0.0062 (10)	0.0027 (9)	0.0007 (9)
C2	0.0170 (12)	0.0130 (11)	0.0180 (12)	0.0036 (9)	0.0013 (9)	0.0013 (9)
C3	0.0226 (13)	0.0124 (11)	0.0195 (12)	0.0063 (10)	0.0063 (10)	0.0050 (9)
C4	0.0228 (13)	0.0148 (11)	0.0116 (11)	0.0083 (10)	0.0025 (9)	0.0024 (9)
C5	0.0166 (12)	0.0149 (11)	0.0191 (12)	0.0049 (9)	0.0005 (9)	0.0004 (9)
C6	0.0201 (12)	0.0121 (11)	0.0152 (11)	0.0052 (9)	0.0046 (9)	0.0037 (9)
C7	0.0183 (12)	0.0217 (13)	0.0171 (12)	0.0047 (10)	0.0041 (9)	0.0068 (10)

Geometric parameters (Å, º) top

O21—N2	1.233 (3)	N71—H71B	0.89 (3)
O22—N2	1.236 (3)	N71—H71A	0.85 (2)
O41—N4	1.243 (2)	N72—H72A	0.91 (3)
O42—N4	1.228 (3)	N72—H72B	0.812 (19)
O61—N6	1.237 (2)	C1—C2	1.432 (3)
O62—N6	1.224 (2)	C1—C6	1.437 (3)
N1—C1	1.337 (3)	C2—C3	1.379 (3)
N1—C7	1.321 (3)	C3—C4	1.385 (3)
N2—C2	1.459 (3)	C4—C5	1.392 (3)
N4—C4	1.453 (3)	C5—C6	1.365 (3)
N6—C6	1.475 (3)	C3—H3	0.9500
N71—C7	1.351 (3)	C5—H5	0.9500
N72—C7	1.330 (3)

C1—N1—C7	124.54 (18)	N2—C2—C1	120.30 (17)
O21—N2—O22	123.64 (17)	N2—C2—C3	115.16 (19)
O21—N2—C2	118.8 (2)	C1—C2—C3	124.4 (2)
O22—N2—C2	117.56 (18)	C2—C3—C4	118.7 (2)
O41—N4—O42	123.57 (17)	C3—C4—C5	121.37 (18)
O41—N4—C4	117.74 (19)	N4—C4—C5	119.2 (2)
O42—N4—C4	118.68 (18)	N4—C4—C3	119.42 (19)
O61—N6—O62	124.34 (16)	C4—C5—C6	118.0 (2)
O61—N6—C6	117.29 (16)	N6—C6—C5	116.8 (2)
O62—N6—C6	118.37 (16)	N6—C6—C1	117.58 (16)
C7—N71—H71B	119.9 (16)	C1—C6—C5	125.6 (2)
H71A—N71—H71B	117 (2)	N71—C7—N72	118.72 (19)
C7—N71—H71A	116.2 (15)	N1—C7—N71	122.7 (2)
H72A—N72—H72B	116 (2)	N1—C7—N72	118.5 (2)
C7—N72—H72A	120.5 (16)	C2—C3—H3	121.00
C7—N72—H72B	123.2 (17)	C4—C3—H3	121.00
N1—C1—C6	119.56 (19)	C4—C5—H5	121.00
N1—C1—C2	128.4 (2)	C6—C5—H5	121.00
C2—C1—C6	111.81 (17)

C7—N1—C1—C2	−38.7 (3)	N1—C1—C2—N2	1.5 (3)
C7—N1—C1—C6	147.8 (2)	C2—C1—C6—N6	176.51 (18)
C1—N1—C7—N72	151.3 (2)	N1—C1—C2—C3	−174.5 (2)
C1—N1—C7—N71	−31.4 (3)	C2—C1—C6—C5	−2.6 (3)
O21—N2—C2—C1	−40.4 (3)	C6—C1—C2—N2	175.47 (19)
O22—N2—C2—C1	140.4 (2)	N1—C1—C6—C5	172.0 (2)
O22—N2—C2—C3	−43.1 (3)	N1—C1—C6—N6	−9.0 (3)
O21—N2—C2—C3	136.0 (2)	C6—C1—C2—C3	−0.6 (3)
O41—N4—C4—C3	9.1 (3)	C1—C2—C3—C4	2.9 (3)
O41—N4—C4—C5	−170.2 (2)	N2—C2—C3—C4	−173.4 (2)
O42—N4—C4—C5	8.6 (3)	C2—C3—C4—C5	−2.2 (3)
O42—N4—C4—C3	−172.1 (2)	C2—C3—C4—N4	178.5 (2)
O62—N6—C6—C5	134.5 (2)	N4—C4—C5—C6	178.6 (2)
O61—N6—C6—C5	−44.7 (3)	C3—C4—C5—C6	−0.7 (3)
O61—N6—C6—C1	136.2 (2)	C4—C5—C6—C1	3.3 (4)
O62—N6—C6—C1	−44.7 (3)	C4—C5—C6—N6	−175.84 (19)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N71—H71A···O41ⁱ	0.85 (2)	2.28 (2)	3.108 (3)	165.7 (18)
N71—H71B···O21ⁱⁱ	0.89 (3)	2.27 (3)	3.155 (2)	173 (2)
N72—H72A···O42ⁱⁱⁱ	0.91 (3)	2.38 (3)	3.180 (3)	147 (2)
N72—H72A···O62^iv	0.91 (3)	2.37 (3)	3.058 (3)	132 (2)
N72—H72B···O22ⁱⁱ	0.812 (19)	2.342 (19)	3.139 (2)	168 (2)
C5—H5···O61^v	0.95	2.43	3.339 (3)	159

Symmetry codes: (i) −x+2, −y, −z+2; (ii) −x+1, −y, −z+1; (iii) −x+2, −y+1, −z+2; (iv) −x+2, −y+1, −z+1; (v) −x+3, −y+1, −z+2.

Experimental details

Crystal data
Chemical formula	C₇H₆N₆O₆
M_r	270.18
Crystal system, space group	Triclinic, P1
Temperature (K)	130
a, b, c (Å)	7.6596 (10), 7.7316 (10), 9.0411 (12)
α, β, γ (°)	104.045 (3), 95.004 (2), 103.121 (2)
V (Å³)	500.08 (11)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.16
Crystal size (mm)	0.15 × 0.10 × 0.10

Data collection
Diffractometer	Bruker CCD area-detector diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	2614, 1739, 1344
R_int	0.055
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.083, 0.92
No. of reflections	1739
No. of parameters	188
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.21

Computer programs: SMART (Bruker, 2000), SMART, SAINT (Bruker, 1999), SHELXS97 Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), PLATON.