4-Meth­oxy­benzamidinium chloride monohydrate

Irrera, S.; Portalone, G.

doi:10.1107/S1600536812041219

organic compounds

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ISSN: 2056-9890

Volume 68| Part 11| November 2012| Page o3083

doi:10.1107/S1600536812041219

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4-Methoxybenzamidinium chloride monohydrate

Simona Irrera ^a and Gustavo Portalone ^a ^*

^aChemistry Department, "Sapienza" University of Rome, P.le A. Moro, 5, I-00185 Rome, Italy
^*Correspondence e-mail: g.portalone@caspur.it

(Received 30 September 2012; accepted 1 October 2012; online 6 October 2012)

In the cation of the title compound, C₈H₁₁N₂O⁺·Cl⁻·H₂O, the C—N bonds of the amidinium group are identical within experiemental error [1.305 (2) and 1.304 (2) Å], and its plane forms a dihedral angle of 25.83 (8)° with the phenyl ring. The ionic components are associated in the crystal into polymeric hydrogen-bonded supramolecular tapes stabilized by N—H⁺⋯Cl⁻ and N—H⁺⋯Ow intermolecular hydrogen bonds, and by Ow—H⋯Cl⁻ interactions.

Related literature

For the biological and pharmacological relevance of benzamidine, see: Marquart et al. (1983 ); Sprang et al. (1987 ); Bode et al. (1990 ); Powers & Harper (1999 ); Grzesiak et al. (2000 ). For structural analysis of proton-transfer adducts containing molecules of biological interest, see: Portalone (2011a ); Portalone & Irrera (2011 ). For the supramolecular association in proton-transfer adducts containing benzamidinium cations, see; Portalone (2010 , 2011b , 2012 ). For hydrogen-bond motifs, see: Bernstein et al. (1995 ).

Experimental

Crystal data

C₈H₁₁N₂O⁺·Cl⁻·H₂O
M_r = 204.65
Monoclinic, P 2₁ /c
a = 11.3029 (7) Å
b = 9.3142 (5) Å
c = 9.9983 (6) Å
β = 99.820 (6)°
V = 1037.17 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.34 mm⁻¹
T = 298 K
0.30 × 0.27 × 0.25 mm

Data collection

Oxford Diffraction Xcalibur S CCD diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006 $[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ) T_min = 0.905, T_max = 0.968
7158 measured reflections
2989 independent reflections
1947 reflections with I > 2σ(I)
R_int = 0.018

Refinement

R[F² > 2σ(F²)] = 0.043
wR(F²) = 0.113
S = 0.97
2989 reflections
144 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯Cl1	0.81 (2)	2.85 (2)	3.5523 (18)	145 (2)
N1—H1B⋯O2W	0.75 (2)	2.06 (2)	2.805 (2)	168 (2)
N2—H2A⋯Cl1	0.96 (2)	2.25 (2)	3.1850 (16)	164.4 (16)
N2—H2B⋯Cl1ⁱ	0.82 (2)	2.43 (2)	3.201 (2)	157.5 (18)
O2W—HWA⋯Cl1ⁱⁱ	0.82 (3)	2.36 (3)	3.1731 (18)	170 (3)
O2W—HWB⋯Cl1ⁱⁱⁱ	0.87 (2)	2.29 (2)	3.1603 (17)	174.8 (19)
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) -x+1, -y+1, -z+1; (iii) $[-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 $[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006 $[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812041219/qm2085sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812041219/qm2085Isup2.hkl

checkCIF report

Comment top

This Laboratory is currently engaged in systematic structural analysis of proton-transfer adducts containing molecules of biological interest (Portalone, 2011a; Portalone & Irrera, 2011). In this context benzamidine derivatives, which have shown strong biological and pharmacological activity (Powers & Harper, 1999; Grzesiak et al., 2000), are being used in our group as bricks for supramolecular construction (Portalone, 2010, 2011b, 2012). Indeed, these molecules are strong Lewis bases and their cations can be easily anchored onto numerous inorganic and organic anions and polyanions, largely because of the presence of four potential donor sites for hydrogen-bonding. Benzamidinium ions have also been included in a number of protein structures (Marquart et al., 1983; Sprang et al., 1987; Bode et al., 1990).

The asymmetric unit of (I) comprises one non-planar 4-methoxybenzamidinium cation, one chloride anion and one water molecule of crystallization (Fig. 1).

In the cation the amidinium group forms a dihedral angle of 25.83 (8)° with the mean plane of the phenyl ring, which agrees with the values observed in protonated benzamidinium ions (23.2 - 30.4°, Portalone, 2010, 2012). The lack of planarity in all these systems is obviously caused by steric hindrances between the H atoms of the aromatic ring and the amidine moiety. This conformation is rather common in benzamidinium-containing small-molecule crystal structures, with the exception of benzamidinium diliturate, where the benzamidinium cation is planar (Portalone, 2010). The pattern of bond lengths and bond angles of the 4-methoxybenzamidinium cation agrees with that reported in previous structural investigations (Portalone, 2010, 2012). In particular the amidinium group, true to one's expectations, features similar C—N bonds [1.305 (2) and 1.304 (2) Å], evidencing the delocalization of the π electrons and their double-bond character.

Analysis of the crystal packing of (I), (Fig. 2), shows that the ions are associated in the crystal by six distinct N—H⁺···Cl^-, N—H⁺···Ow and Ow—H···Cl^- intermolecular hydrogen bonds (Table 1). Each amidinium unit is bound to two chloride anions by three weak hydrogen bonds (N⁺···Cl^- = 3.185 (2) - 3.552 (2) Å) and to one water molecule by one N—H⁺···Ow interaction, just forming two R³₅(10) and one R¹₂(6) supramolecular synthons (Bernstein et al., 1995). Both of these R³₅(10) and R¹₂(6) motifs lead to the formation of one dimensional polymeric hydrogen-bonded supramolecular tapes approximately along the crystallographic b axis. The water molecule, which plays a dual role as both donor and acceptor in hydrogen bonding interactions, acts as a bridge between tapes through the remaining two Ow—H···Cl^- intermolecular interactions.

Related literature top

For the biological and pharmacological relevance of benzamidine, see: Marquart et al. (1983); Sprang et al. (1987); Bode et al. (1990); Powers & Harper (1999); Grzesiak et al. (2000). For structural analysis of proton-transfer adducts containing molecules of biological interest, see: Portalone (2011a); Portalone & Irrera (2011). For the supramolecular association in proton-transfer adducts containing benzamidinium cations, see; Portalone (2010, 2011b, 2012). For hydrogen-bond motifs, see: Bernstein et al. (1995).

Experimental top

4-methoxybenzamidine (1 mmol, Fluka at 96% purity) was dissolved without further purification in 6 ml of hot water and heated under reflux for 3 h. While stirring, HCl (6 mol L^-1) was added dropwise until the pH reached 2. After cooling the solution to ambient temperature, colourless crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation of the solvent over two weeks.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. The asymmetric unit of (I), showing the atom-labelling scheme. Displacements ellipsoids are at the 50% probability level. H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. Crystal packing diagram for (I), viewed approximately down a. Displacements ellipsoids are at the 50% probability level. H atoms are shown as small spheres of arbitrary radii. For the sake of clarity, H atoms not involved in hydrogen bonding have been omitted. Hydrogen bonding is indicated by dashed lines.

4-Methoxybenzamidinium chloride monohydrate top

Crystal data top

C₈H₁₁N₂O⁺·Cl⁻·H₂O	F(000) = 432
M_r = 204.65	D_x = 1.311 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 3182 reflections
a = 11.3029 (7) Å	θ = 2.8–32.2°
b = 9.3142 (5) Å	µ = 0.34 mm⁻¹
c = 9.9983 (6) Å	T = 298 K
β = 99.820 (6)°	Tablets, colourless
V = 1037.17 (11) Å³	0.30 × 0.27 × 0.25 mm
Z = 4

Data collection top

Oxford Diffraction Xcalibur S CCD diffractometer	2989 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1947 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.018
Detector resolution: 16.0696 pixels mm^-1	θ_max = 30.0°, θ_min = 2.9°
ω and ϕ scans	h = −15→13
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006)	k = −13→13
T_min = 0.905, T_max = 0.968	l = −14→14
7158 measured reflections

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)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.113	H atoms treated by a mixture of independent and constrained refinement
S = 0.97	w = 1/[σ²(F_o²) + (0.0667P)²] where P = (F_o² + 2F_c²)/3
2989 reflections	(Δ/σ)_max < 0.001
144 parameters	Δρ_max = 0.22 e Å⁻³
0 restraints	Δρ_min = −0.15 e Å⁻³

Crystal data top

C₈H₁₁N₂O⁺·Cl⁻·H₂O	V = 1037.17 (11) Å³
M_r = 204.65	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 11.3029 (7) Å	µ = 0.34 mm⁻¹
b = 9.3142 (5) Å	T = 298 K
c = 9.9983 (6) Å	0.30 × 0.27 × 0.25 mm
β = 99.820 (6)°

Data collection top

Oxford Diffraction Xcalibur S CCD diffractometer	2989 independent reflections
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006)	1947 reflections with I > 2σ(I)
T_min = 0.905, T_max = 0.968	R_int = 0.018
7158 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.043	0 restraints
wR(F²) = 0.113	H atoms treated by a mixture of independent and constrained refinement
S = 0.97	Δρ_max = 0.22 e Å⁻³
2989 reflections	Δρ_min = −0.15 e Å⁻³
144 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
Cl1	0.59874 (3)	0.29686 (5)	0.19860 (4)	0.06143 (17)
O1	0.02187 (9)	0.02872 (12)	0.72746 (11)	0.0585 (3)
N1	0.37553 (14)	0.36637 (18)	0.40096 (17)	0.0577 (4)
H1A	0.4215 (18)	0.391 (3)	0.351 (2)	0.087 (7)*
H1B	0.3457 (16)	0.424 (2)	0.4357 (19)	0.070 (7)*
N2	0.40806 (13)	0.1372 (2)	0.34687 (16)	0.0609 (4)
H2A	0.4716 (18)	0.167 (2)	0.300 (2)	0.082 (6)*
H2B	0.3898 (16)	0.052 (3)	0.3475 (19)	0.077 (7)*
C1	0.26509 (11)	0.18152 (15)	0.49586 (13)	0.0400 (3)
C2	0.17291 (12)	0.26955 (17)	0.52024 (16)	0.0499 (4)
H2	0.1669	0.3620	0.4847	0.060*
C3	0.08913 (12)	0.22277 (17)	0.59666 (16)	0.0497 (4)
H3	0.0273	0.2832	0.6120	0.060*
C4	0.09816 (11)	0.08562 (16)	0.64994 (14)	0.0425 (3)
C5	0.19078 (12)	−0.00346 (17)	0.62752 (15)	0.0489 (4)
H5	0.1974	−0.0953	0.6645	0.059*
C6	0.27322 (12)	0.04365 (16)	0.55054 (14)	0.0460 (3)
H6	0.3348	−0.0171	0.5350	0.055*
C7	0.35238 (11)	0.22994 (17)	0.41160 (14)	0.0460 (4)
C8	−0.07725 (14)	0.1140 (2)	0.75071 (19)	0.0684 (5)
H8A	−0.0482 (3)	0.2006 (11)	0.7969 (13)	0.103*
H8B	−0.1241 (9)	0.0612 (8)	0.8055 (12)	0.103*
H8C	−0.1263 (8)	0.1375 (12)	0.6654 (9)	0.103*
O2W	0.27853 (14)	0.61140 (16)	0.50438 (18)	0.0783 (4)
HWA	0.319 (3)	0.631 (4)	0.579 (3)	0.155 (14)*
HWB	0.3124 (17)	0.667 (2)	0.452 (2)	0.077 (6)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0604 (3)	0.0699 (3)	0.0594 (3)	−0.00364 (19)	0.02536 (19)	0.0085 (2)
O1	0.0518 (6)	0.0581 (7)	0.0737 (7)	0.0039 (5)	0.0337 (5)	0.0110 (6)
N1	0.0595 (8)	0.0550 (9)	0.0642 (9)	−0.0047 (7)	0.0267 (7)	0.0125 (8)
N2	0.0583 (8)	0.0688 (11)	0.0628 (9)	−0.0090 (8)	0.0311 (7)	−0.0027 (8)
C1	0.0358 (6)	0.0472 (8)	0.0373 (7)	−0.0039 (6)	0.0072 (5)	0.0001 (6)
C2	0.0510 (8)	0.0403 (8)	0.0604 (9)	0.0036 (6)	0.0156 (7)	0.0089 (7)
C3	0.0437 (7)	0.0463 (9)	0.0629 (9)	0.0077 (6)	0.0195 (6)	0.0020 (7)
C4	0.0384 (6)	0.0464 (8)	0.0443 (7)	−0.0017 (6)	0.0117 (5)	0.0002 (6)
C5	0.0496 (7)	0.0421 (8)	0.0584 (9)	0.0047 (7)	0.0191 (6)	0.0082 (7)
C6	0.0420 (7)	0.0449 (8)	0.0541 (8)	0.0078 (6)	0.0167 (6)	0.0032 (7)
C7	0.0405 (7)	0.0559 (10)	0.0420 (7)	−0.0040 (6)	0.0084 (6)	0.0045 (7)
C8	0.0503 (8)	0.0838 (13)	0.0787 (12)	0.0101 (8)	0.0329 (8)	0.0039 (10)
O2W	0.1035 (11)	0.0605 (8)	0.0747 (10)	−0.0175 (8)	0.0258 (9)	0.0015 (7)

Geometric parameters (Å, º) top

O1—C4	1.3613 (16)	C2—H2	0.9300
O1—C8	1.4243 (18)	C3—C4	1.381 (2)
N1—C7	1.305 (2)	C3—H3	0.9300
N1—H1A	0.81 (2)	C4—C5	1.3837 (19)
N1—H1B	0.75 (2)	C5—C6	1.3776 (19)
N2—C7	1.304 (2)	C5—H5	0.9300
N2—H2A	0.96 (2)	C6—H6	0.9300
N2—H2B	0.82 (2)	C8—H8A	0.9596
C1—C2	1.3798 (19)	C8—H8B	0.9596
C1—C6	1.3926 (19)	C8—H8C	0.9596
C1—C7	1.4731 (18)	O2W—HWA	0.82 (3)
C2—C3	1.385 (2)	O2W—HWB	0.87 (2)

C4—O1—C8	117.92 (13)	C3—C4—C5	120.02 (12)
C7—N1—H1A	119.0 (17)	C6—C5—C4	120.14 (14)
C7—N1—H1B	123.3 (15)	C6—C5—H5	119.9
H1A—N1—H1B	118 (2)	C4—C5—H5	119.9
C7—N2—H2A	120.7 (11)	C5—C6—C1	120.49 (12)
C7—N2—H2B	119.6 (14)	C5—C6—H6	119.8
H2A—N2—H2B	119.7 (18)	C1—C6—H6	119.8
C2—C1—C6	118.68 (12)	N2—C7—N1	118.95 (15)
C2—C1—C7	121.24 (13)	N2—C7—C1	120.53 (15)
C6—C1—C7	120.07 (12)	N1—C7—C1	120.52 (15)
C1—C2—C3	121.24 (14)	O1—C8—H8A	109.5
C1—C2—H2	119.4	O1—C8—H8B	109.5
C3—C2—H2	119.4	H8A—C8—H8B	109.5
C4—C3—C2	119.43 (13)	O1—C8—H8C	109.5
C4—C3—H3	120.3	H8A—C8—H8C	109.5
C2—C3—H3	120.3	H8B—C8—H8C	109.5
O1—C4—C3	124.57 (12)	HWA—O2W—HWB	100 (3)
O1—C4—C5	115.41 (13)

C6—C1—C2—C3	−0.4 (2)	C3—C4—C5—C6	−0.9 (2)
C7—C1—C2—C3	178.39 (14)	C4—C5—C6—C1	0.7 (2)
C1—C2—C3—C4	0.2 (2)	C2—C1—C6—C5	−0.1 (2)
C8—O1—C4—C3	2.8 (2)	C7—C1—C6—C5	−178.88 (14)
C8—O1—C4—C5	−178.22 (14)	C2—C1—C7—N2	−153.81 (15)
C2—C3—C4—O1	179.33 (14)	C6—C1—C7—N2	25.0 (2)
C2—C3—C4—C5	0.4 (2)	C2—C1—C7—N1	26.4 (2)
O1—C4—C5—C6	−179.90 (14)	C6—C1—C7—N1	−154.78 (15)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1	0.81 (2)	2.85 (2)	3.5523 (18)	145 (2)
N1—H1B···O2W	0.75 (2)	2.06 (2)	2.805 (2)	168 (2)
N2—H2A···Cl1	0.96 (2)	2.25 (2)	3.1850 (16)	164.4 (16)
N2—H2B···Cl1ⁱ	0.82 (2)	2.43 (2)	3.201 (2)	157.5 (18)
O2W—HWA···Cl1ⁱⁱ	0.82 (3)	2.36 (3)	3.1731 (18)	170 (3)
O2W—HWB···Cl1ⁱⁱⁱ	0.87 (2)	2.29 (2)	3.1603 (17)	174.8 (19)

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

Experimental details

Crystal data
Chemical formula	C₈H₁₁N₂O⁺·Cl⁻·H₂O
M_r	204.65
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	11.3029 (7), 9.3142 (5), 9.9983 (6)
β (°)	99.820 (6)
V (Å³)	1037.17 (11)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.34
Crystal size (mm)	0.30 × 0.27 × 0.25

Data collection
Diffractometer	Oxford Diffraction Xcalibur S CCD diffractometer
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2006)
T_min, T_max	0.905, 0.968
No. of measured, independent and observed [I > 2σ(I)] reflections	7158, 2989, 1947
R_int	0.018
(sin θ/λ)_max (Å⁻¹)	0.704

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.043, 0.113, 0.97
No. of reflections	2989
No. of parameters	144
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.15

Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1	0.81 (2)	2.85 (2)	3.5523 (18)	145 (2)
N1—H1B···O2W	0.75 (2)	2.06 (2)	2.805 (2)	168 (2)
N2—H2A···Cl1	0.96 (2)	2.25 (2)	3.1850 (16)	164.4 (16)
N2—H2B···Cl1ⁱ	0.82 (2)	2.43 (2)	3.201 (2)	157.5 (18)
O2W—HWA···Cl1ⁱⁱ	0.82 (3)	2.36 (3)	3.1731 (18)	170 (3)
O2W—HWB···Cl1ⁱⁱⁱ	0.87 (2)	2.29 (2)	3.1603 (17)	174.8 (19)

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

References

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Volume 68| Part 11| November 2012| Page o3083

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