4-Ammonio­benzamidinium dichloride

Legrand, Y.M.; Lee, A. van der; Barboiu, M.

doi:10.1107/S1600536808010179

organic compounds

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ISSN: 2056-9890

Volume 64| Part 6| June 2008| Pages o967-o968

doi:10.1107/S1600536808010179

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4-Ammoniobenzamidinium dichloride

Y. M. Legrand,^a ^* A. van der Lee ^a and M. Barboiu ^a

^aInstitut Européen des Membranes, UMR 5635, CC 047 Université de Montpellier II, Montpellier, France
^*Correspondence e-mail: yves-marie.legrand@iemm.univ-montp2.fr

(Received 8 April 2008; accepted 14 April 2008; online 3 May 2008)

The crystal structure of the title compound, C₇H₁₁N₃²⁺·2Cl⁻, has been determined as part of a project focusing on the ability of the benzamidine system to form strong hydrogen bonds in aqueous media. It is commonly used as a ligand in affinity chromatography for purification and immobilization of enzymes. A twofold rotation axis runs along the axis of the cation. The orientation of the amidinium group with respect to the benzene ring is indicated by the N—C—C—C torsion angle of 40.2 (1)°. In the crystal structure, cations and anions are linked via hydrogen bonds. The chloride anion is surrounded by four ammonium cations in a tetrahedral environment. The aromatic rings of the amidinium cations are π-stacked, with a centroid–centroid distance of 4.178 (1) Å.

Related literature

For related literature, see: Boyd (1991 ); Nguyen & Loung (1990 ); Jarak et al. (2005 ); Hranjec et al. (2003 ); Danan et al. (1997 ); Del Poeta, Schell, Dykstra, Jones, Tidwell, Czarny et al. (1998 ); Del Poeta, Schell, Dykstra, Jones, Tidwell, Kumar et al., (1998 ); Janiak (2000 ); Fujita et al. (1995 ); Müller et al. (2006 ); Kimata et al. (1990 ). For examples of related tubular superstructures, see: Barboiu et al. (2003 ); Blondeau et al. (2005 ).

Experimental

Crystal data

C₇H₁₁N₃²⁺·2Cl⁻
M_r = 208.09
Monoclinic, C 2/c
a = 4.1779 (2) Å
b = 20.9388 (10) Å
c = 11.6260 (5) Å
β = 94.920 (4)°
V = 1013.30 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.59 mm⁻¹
T = 175 K
0.49 × 0.09 × 0.05 mm

Data collection

Oxford Diffraction XCalibur diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007 $[Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]$ ) T_min = 0.95, T_max = 0.97
7752 measured reflections
1750 independent reflections
1144 reflections with I > 2σ(I)
R_int = 0.018

Refinement

R[F² > 2σ(F²)] = 0.027
wR(F²) = 0.034
S = 1.00
1144 reflections
59 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H9⋯Cl1ⁱ	0.90	2.35	3.2247 (13)	166
N2—H10⋯Cl1	0.92	2.32	3.2142 (13)	162
N8—H13⋯Cl1ⁱⁱ	0.85	2.26	3.1031 (6)	173
N8—H14⋯Cl1ⁱⁱⁱ	0.94	2.20	3.1369 (6)	176
C5—H11⋯Cl1^iv	1.00	2.70	3.6806 (13)	165
Symmetry codes: (i) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+2]$ ; (ii) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iii) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iv) $[-x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+2]$ .

Data collection: CrysAlis CCD (Oxford Diffraction, 2007 $[Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]$ ); cell refinement: CrysAlis RED (Oxford Diffraction, 2007 $[Oxford Diffraction (2007). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]$ ); data reduction: CrysAlis RED; program(s) used to solve structure: SIR2004 (Burla et al., 2003 ); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ); molecular graphics: CAMERON (Watkin et al., 1996 ) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: CRYSTALS.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808010179/wn2252sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808010179/wn2252Isup2.hkl

checkCIF report

Comment top

Several types of heteroditopic receptors, including the title compound, are being used in our group as bricks for supramolecular construction (Barboiu et al., 2003, Blondeau et al., 2005). Among other functions, amidine compounds have shown antiparasitic (Danan et al., 1997) and antifungal activity (Del Poeta, Schell, Dykstra, Jones, Tidwell, Czarny et al., 1998; Del Poeta, Schell, Dykstra, Jones, Tidwell, Kumar et al., 1998). Indeed, this class of compounds has been widely studied for its biological activities. Surprisingly, only one crystal structure of an aminobenzamidine derivative has been published so far (Jarak et al., 2005). Our project deals with the construction of supramolecular architectures based on hydrogen bonding in aqueous media. This is possible due to the strength of the bonds formed between the very electrophilic amidinium unit and the nucleophilic character of acids, for example. Superstructures made of co-crystals have been designed and surprising results have been achieved by Fujita et al. (1995) and Müller et al. (2006). The amidine group also forms a well recognized class of anticancer compounds (Boyd, 1991, Hranjec et al., 2003) and, based on the same properties, can also be used as ligands in affinity chromatography to immobilize enzymes (Nguyen & Loung, 1990 and Kimata et al., 1990).

The molecule of the title compound (Fig. 1) is not planar. The amidinium group has a synclinal disposition with respect to the benzene ring (N2—C3—C4—C5 = -40.2 (1)°). A twofold rotation axis runs along the axis of the cation. The observed deviation from coplanarity might serve to accommodate the formation of intermolecular hydrogen bonds with chloride ions. The three ammonium protons are free to rotate about the C7—N8 bond. These protons were found by Fourier difference maps at four positions (2 + 2 by symmetry) which appears to be in line with the four chloride anions surrounding the ammonium group (N···Cl = 3.103 Å). The site occupation factors of the four ammonium protons was set at 0.75, as there are, in fact, only three protons attached to this ammonium nitrogen. As Fig. 2 shows, rows of head-to-tail benzamidine are stacked alternately. Interestingly, three of four nitrogen atoms form a plane on which the chloride atom sits, almost perfectly. Each chloride anion is bound to four nitrogen cations by weak hydrogen bonds (N···Cl = 3.103 (1)–3.225 (1) Å), while each amidinium unit is bound to eight chloride anions (four times through the ammonium site, twice through each amidinium nitrogen). This produces a singular pyramidal architecture, as depicted in Fig. 3. The packing is determined by these hydrogen bonds, but also by π-stacking. The aromatic rings of the amidinium cations adopt a parallel offset conformation. The distance Cg···Cg between the centroids of two adjacent rings is 4.178 (1) Å, whereas the angle between the ring-centroid vector and the ring normal of one of the amidine rings is 27.7 (1)° (with a perpendicular interplanar distance of 3.7 Å). The angle between the two benzene rings is 0.02°. These values can be considered to be normal for π-π interactions (Janiak, 2000). Fig. 3 also shows both the hydrogen bonding pattern and the interactions between the aromatic groups held together by π-π non-covalent intermolecular interactions.

Related literature top

For related literature, see: Boyd (1991); Nguyen & Loung (1990); Jarak et al. (2005); Hranjec et al. (2003); Danan et al. (1997); Del Poeta, Schell, Dykstra, Jones, Tidwell, Czarny et al. (1998); Del Poeta, Schell, Dykstra, Jones, Tidwell, Kumar et al., (1998); Janiak (2000); Fujita et al. (1995); Müller et al. (2006); Kimata et al. (1990). For examples of related tubular superstructures, see: Barboiu et al. (2003); Blondeau et al. (2005).

Experimental top

The title compound is commercially available. To purify it, it has been crystallized from a mixture of water and methanol (10:2). The crystals formed over a period of one week.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); program(s) used to solve structure: SIR2004 (Burla et al., 2003); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996) and Mercury (Macrae et al., 2006); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures top

	Fig. 1. Representation of the structure of the title compound, with the numbering scheme adopted. The Cl atoms is light-green, the C atom green, the N atoms blue and the H atoms in grey. Displacement ellipsoids are drawn at the 50% probability level [symmetry code: (i) -x, y, -z + 3/2].
	Fig. 2. The two-dimensional framework of the title compound, viewed down the a cell direction.
	Fig. 3. Representation of the hydrogen bonding network between the cations and the chloride anions, giving rise to a pyramidal scaffold architecture. Hydrogen bonds are denoted by dotted lines.

4-Ammoniobenzamidinium dichloride top

Crystal data top

C₇H₁₁N₃²⁺·2Cl⁻	F(000) = 432
M_r = 208.09	D_x = 1.364 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 4424 reflections
a = 4.1779 (2) Å	θ = 4–32°
b = 20.9388 (10) Å	µ = 0.59 mm⁻¹
c = 11.6260 (5) Å	T = 175 K
β = 94.920 (4)°	Stick, colourless
V = 1013.30 (8) Å³	0.49 × 0.09 × 0.05 mm
Z = 4

Data collection top

Oxford Diffraction XCALIBUR diffractometer	1750 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1144 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.018
Detector resolution: 16.0143 pixels mm^-1	θ_max = 32.7°, θ_min = 3.9°
ω scans	h = −5→6
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007); empirical (using intensity measurements) absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm	k = −31→29
T_min = 0.95, T_max = 0.97	l = −17→15
7752 measured reflections

Refinement top

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.027	H-atom parameters constrained
wR(F²) = 0.034	Method, part 1, Chebychev polynomial [Watkin, D. J. (1994). Acta Cryst. A50, 411-437. Prince, E. (1982). Mathematical Techniques in Crystallography and Materials Science. New York: Springer-Verlag.] [weight] = 1.0/[A₀T₀(x) + A₁T₁(x) ··· + A_n-1]T_n-1(x)] where A_i are the Chebychev coefficients listed below and x = F /Fmax Method = Robust Weighting (Prince, 1982) W = [weight] [1-(deltaF/6*sigmaF)²]² A_i are 20.0 -14.7 15.4
S = 1.01	(Δ/σ)_max = 0.001
1144 reflections	Δρ_max = 0.34 e Å⁻³
59 parameters	Δρ_min = −0.20 e Å⁻³
2 restraints

Crystal data top

C₇H₁₁N₃²⁺·2Cl⁻	V = 1013.30 (8) Å³
M_r = 208.09	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 4.1779 (2) Å	µ = 0.59 mm⁻¹
b = 20.9388 (10) Å	T = 175 K
c = 11.6260 (5) Å	0.49 × 0.09 × 0.05 mm
β = 94.920 (4)°

Data collection top

Oxford Diffraction XCALIBUR diffractometer	1750 independent reflections
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007); empirical (using intensity measurements) absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm	1144 reflections with I > 2σ(I)
T_min = 0.95, T_max = 0.97	R_int = 0.018
7752 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.027	2 restraints
wR(F²) = 0.034	H-atom parameters constrained
S = 1.01	Δρ_max = 0.34 e Å⁻³
1144 reflections	Δρ_min = −0.20 e Å⁻³
59 parameters

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Cl1	0.03602 (8)	0.146532 (14)	0.92627 (3)	0.0297
N2	0.0839 (4)	0.29292 (6)	0.84632 (10)	0.0380
C3	0.0000	0.32303 (8)	0.7500	0.0271
C4	0.0000	0.39368 (8)	0.7500	0.0236
C5	−0.1109 (3)	0.42664 (6)	0.84251 (11)	0.0282
C6	−0.1138 (3)	0.49282 (6)	0.84200 (11)	0.0296
C7	0.0000	0.52485 (8)	0.7500	0.0264
N8	0.000000 (10)	0.59418 (7)	0.750000 (10)	0.0381
H9	0.1600	0.3149	0.9089	0.0500*
H10	0.0659	0.2491	0.8520	0.0500*
H11	−0.1867	0.4022	0.9091	0.0500*
H12	−0.1892	0.5181	0.9058	0.0500*
H13	0.1342	0.6109	0.8006	0.0500*	0.7500
H14	−0.1333	0.6116	0.8033	0.0500*	0.7500

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.04130 (17)	0.02485 (14)	0.02214 (13)	−0.00435 (13)	−0.00233 (9)	−0.00073 (11)
N2	0.0652 (9)	0.0209 (5)	0.0252 (5)	−0.0030 (5)	−0.0122 (5)	0.0038 (4)
C3	0.0386 (9)	0.0198 (7)	0.0218 (7)	0.0000	−0.0043 (6)	0.0000
C4	0.0324 (9)	0.0184 (6)	0.0191 (6)	0.0000	−0.0030 (6)	0.0000
C5	0.0403 (7)	0.0236 (5)	0.0208 (5)	0.0006 (5)	0.0021 (4)	0.0000 (4)
C6	0.0379 (7)	0.0238 (6)	0.0265 (5)	0.0036 (5)	−0.0011 (4)	−0.0043 (4)
C7	0.0275 (8)	0.0180 (6)	0.0319 (8)	0.0000	−0.0074 (6)	0.0000
N8	0.0296 (8)	0.0177 (7)	0.0651 (12)	0.0000	−0.0072 (8)	0.0000

Geometric parameters (Å, º) top

N2—C3	1.3064 (13)	C6—C7	1.3810 (16)
N2—H9	0.896	C6—H12	0.985
N2—H10	0.923	C7—N8	1.452 (2)
C3—C4	1.479 (2)	N8—H14ⁱ	0.942
C4—C5	1.3904 (15)	N8—H13ⁱ	0.852
C5—C6	1.3859 (18)	N8—H13	0.852
C5—H11	1.002	N8—H14	0.942

C3—N2—H9	120.0	C6—C7—N8	119.05 (8)
C3—N2—H10	121.5	C6ⁱ—C7—N8	119.05 (8)
H9—N2—H10	118.5	C7—N8—H14ⁱ	112.8
N2—C3—N2ⁱ	122.30 (16)	C7—N8—H13ⁱ	114.3
N2—C3—C4	118.85 (8)	H14ⁱ—N8—H13ⁱ	77.2
C3—C4—C5	119.75 (8)	C7—N8—H13	114.3
C5ⁱ—C4—C5	120.49 (16)	H14ⁱ—N8—H13	84.5
C4—C5—C6	119.76 (13)	H13ⁱ—N8—H13	131.5
C4—C5—H11	119.5	C7—N8—H14	112.8
C6—C5—H11	120.7	H14ⁱ—N8—H14	134.3
C5—C6—C7	119.04 (13)	H13ⁱ—N8—H14	84.5
C5—C6—H12	122.5	H13—N8—H14	77.2
C7—C6—H12	118.5

C(4)—C(5)—C(6)—C(7)	−1.2 (1)	C(5)—C(6)—C(7)—N(8)	−179.4 (1)
C(5)—C(4)—C(3)—N(2)	−40.2 (1)

Symmetry code: (i) −x, y, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H9···Cl1ⁱⁱ	0.90	2.35	3.2247 (13)	166
N2—H10···Cl1	0.92	2.32	3.2142 (13)	162
N8—H13···Cl1ⁱⁱⁱ	0.85	2.26	3.1031 (6)	173
N8—H14···Cl1^iv	0.94	2.20	3.1369 (6)	176
C5—H11···Cl1^v	1.00	2.70	3.6806 (13)	165

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

Experimental details

Crystal data
Chemical formula	C₇H₁₁N₃²⁺·2Cl⁻
M_r	208.09
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	175
a, b, c (Å)	4.1779 (2), 20.9388 (10), 11.6260 (5)
β (°)	94.920 (4)
V (Å³)	1013.30 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.59
Crystal size (mm)	0.49 × 0.09 × 0.05

Data collection
Diffractometer	Oxford Diffraction XCALIBUR diffractometer
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2007); empirical (using intensity measurements) absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm
T_min, T_max	0.95, 0.97
No. of measured, independent and observed [I > 2σ(I)] reflections	7752, 1750, 1144
R_int	0.018
(sin θ/λ)_max (Å⁻¹)	0.759

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.034, 1.01
No. of reflections	1144
No. of parameters	59
No. of restraints	2
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.34, −0.20

Computer programs: CrysAlis CCD (Oxford Diffraction, 2007), CrysAlis RED (Oxford Diffraction, 2007), SIR2004 (Burla et al., 2003), CRYSTALS (Betteridge et al., 2003), CAMERON (Watkin et al., 1996) and Mercury (Macrae et al., 2006).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H9···Cl1ⁱ	0.90	2.35	3.2247 (13)	166
N2—H10···Cl1	0.92	2.32	3.2142 (13)	162
N8—H13···Cl1ⁱⁱ	0.85	2.26	3.1031 (6)	173
N8—H14···Cl1ⁱⁱⁱ	0.94	2.20	3.1369 (6)	176
C5—H11···Cl1^iv	1.00	2.70	3.6806 (13)	165

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

Acknowledgements

This work, conducted as part of the award `Dynamic Adaptive Materials for Separation and Sensing Microsystems' (to MB) made under the European Heads of Research Councils and European Science Foundation EURYI (European Young Investigator) Awards Scheme in 2004, was supported by funds from the Participating Organizations of EURYI and the EC Sixth Framework Program (see http://www.esf.org/euryi ). This research was also supported in part by the CNRS and the University of Montpellier II.

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