Two concomitant polymorphs of the molecular salt formed by 2,6-dimethoxybenzoic acid, C
9H
10O
4 (Dmb), with benzamidine, C
7H
8N
2 (benzenecarboximidamide, Benzam) from water solution have been identified. Benzamidinidium 2,6-dimethoxybenzoate, C
7H
9N
2+·C
9H
9O
4- (BenzamH
+·Dmb
-), was obtained through protonation at the imino N atom of Benzam as a result of proton transfer from the acidic hydroxy group of Dmb. In the monoclinic polymorph, (I) (space group
P2
1/
n), the asymmetric unit consists of two Dmb
- anions and two monoprotonated BenzamH
+ cations. In the orthorhombic polymorph, (II) (space group
P2
12
12
1), one Dmb
- anion and one BenzamH
+ cation constitute the asymmetric unit. In both polymorphic salts, the amidinium fragments and carboxylate groups are completely delocalized. This delocalization favours the aggregation of the molecular components of these acid-base complexes into nonplanar dimers with an
R22(8) graph-set motif
via N
+-H
O
- charge-assisted hydrogen bonding. Both the monoclinic and orthorhombic forms exhibit one-dimensional isostructurality, as the crystal structures feature identical hydrogen-bonding motifs consisting of dimers and catemers.
Supporting information
CCDC references: 914652; 914653
Equimolar amounts of benzamidine (Fluka, 95%) and 2,6-dimethoxybenzoic acid
(Sigma Aldrich, 99%), dissolved in ethanol (20 ml), were refluxed for 8 h at
323 K. The mixture was cooled to room temperature and the solvent evaporated
under vacuum. The product was then recrystallized from water to give, after
one week, colourless crystals suitable for X-ray analysis. Careful examination
of the batch under a microscope showed crystals in the form of tablets of (I)
and small prisms of (II) [Both given as tablets in CIF tables -
please
clarify]. The majority of the crystals were (II), with a small quantity of
(I). Unfortunately, any attempts to produce more crystals of polymorph (I) by
repeating the crystallization conditions were unsuccessful. Crystallization of
the molecular salt carried out under a wide range of different sets of
conditions (different solvents, different molar ratios) led systematically to
the orthorhombic polymorph, (II).
In both polymorphs all H atoms were found in a difference map, but for the
final refinements all benzene-bound H atoms were positioned with idealized
geometry and included in the calculations as riding on their parent atoms,
with C—H = 0.97 Å and Uiso = 1.2Ueq(C). Methyl-bound H
atoms were located from idealized local difference electron-density
calculations and their C—H distances were allowed to vary during refinement
using a riding model, with Uiso = 1.5Ueq(C). The positional
and displacement parameters of the H atoms of the amidine groups were freely
refined, giving N—H distances in the range 0.84 (3)–1.00 (3) Å. In the
absence of significant anomalous scattering in this light-atom study of
polymorph (II), Friedel pairs were merged.
For both compounds, data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (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 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
(I) Benzamidinidium 2,6-dimethoxybenzoate
top
Crystal data top
C7H9N2+·C9H9O4− | F(000) = 1280 |
Mr = 302.32 | Dx = 1.250 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2yn | Cell parameters from 71996 reflections |
a = 14.7103 (2) Å | θ = 2.7–32.5° |
b = 11.7174 (1) Å | µ = 0.09 mm−1 |
c = 19.7281 (3) Å | T = 298 K |
β = 109.145 (2)° | Tablet, colourless |
V = 3212.39 (8) Å3 | 0.20 × 0.15 × 0.14 mm |
Z = 8 | |
Data collection top
Oxford Xcalibur S CCD area-detector diffractometer | 5682 independent reflections |
Radiation source: Enhance (Mo) X-ray source | 4978 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.041 |
Detector resolution: 16.0696 pixels mm-1 | θmax = 25.1°, θmin = 2.7° |
ω and ϕ scans | h = −17→17 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | k = −13→13 |
Tmin = 0.982, Tmax = 0.987 | l = −23→23 |
248320 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)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.129 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.18 | w = 1/[σ2(Fo2) + (0.0502P)2 + 1.0275P] where P = (Fo2 + 2Fc2)/3 |
5682 reflections | (Δ/σ)max < 0.001 |
437 parameters | Δρmax = 0.18 e Å−3 |
0 restraints | Δρmin = −0.17 e Å−3 |
Crystal data top
C7H9N2+·C9H9O4− | V = 3212.39 (8) Å3 |
Mr = 302.32 | Z = 8 |
Monoclinic, P21/n | Mo Kα radiation |
a = 14.7103 (2) Å | µ = 0.09 mm−1 |
b = 11.7174 (1) Å | T = 298 K |
c = 19.7281 (3) Å | 0.20 × 0.15 × 0.14 mm |
β = 109.145 (2)° | |
Data collection top
Oxford Xcalibur S CCD area-detector diffractometer | 5682 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | 4978 reflections with I > 2σ(I) |
Tmin = 0.982, Tmax = 0.987 | Rint = 0.041 |
248320 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.058 | 0 restraints |
wR(F2) = 0.129 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.18 | Δρmax = 0.18 e Å−3 |
5682 reflections | Δρmin = −0.17 e Å−3 |
437 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 >
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 | Uiso*/Ueq | |
N1 | 0.03204 (13) | −0.09912 (16) | 0.19097 (9) | 0.0442 (4) | |
H1A | −0.0078 (16) | −0.037 (2) | 0.1779 (12) | 0.058 (6)* | |
H1B | 0.0478 (17) | −0.127 (2) | 0.2356 (14) | 0.064 (7)* | |
N2 | 0.05603 (13) | −0.08038 (15) | 0.08423 (8) | 0.0434 (4) | |
H2A | 0.0065 (15) | −0.0247 (19) | 0.0728 (11) | 0.051 (6)* | |
H2B | 0.0836 (16) | −0.1015 (19) | 0.0499 (12) | 0.057 (6)* | |
C1 | 0.15214 (13) | −0.22020 (16) | 0.16763 (9) | 0.0375 (4) | |
C2 | 0.19618 (18) | −0.2465 (2) | 0.23911 (12) | 0.0658 (7) | |
H2 | 0.1780 | −0.2063 | 0.2757 | 0.079* | |
C3 | 0.2663 (2) | −0.3302 (3) | 0.25849 (14) | 0.0894 (10) | |
H3 | 0.2971 | −0.3487 | 0.3087 | 0.107* | |
C4 | 0.29260 (19) | −0.3871 (2) | 0.20706 (14) | 0.0726 (8) | |
H4 | 0.3416 | −0.4460 | 0.2210 | 0.087* | |
C5 | 0.24997 (19) | −0.3609 (2) | 0.13663 (14) | 0.0661 (7) | |
H5 | 0.2692 | −0.4007 | 0.1004 | 0.079* | |
C6 | 0.17957 (16) | −0.27801 (19) | 0.11630 (11) | 0.0539 (6) | |
H6 | 0.1492 | −0.2602 | 0.0659 | 0.065* | |
C7 | 0.07768 (12) | −0.13012 (15) | 0.14702 (9) | 0.0337 (4) | |
O1 | −0.07302 (11) | 0.10458 (12) | 0.16122 (7) | 0.0517 (4) | |
O2 | −0.08607 (10) | 0.08850 (11) | 0.04679 (6) | 0.0468 (3) | |
O3 | −0.28794 (11) | 0.17659 (14) | 0.06376 (10) | 0.0719 (5) | |
O4 | 0.01547 (13) | 0.33083 (15) | 0.10538 (12) | 0.0840 (6) | |
C8 | −0.13889 (14) | 0.26004 (16) | 0.08429 (9) | 0.0397 (4) | |
C9 | −0.23748 (15) | 0.27510 (18) | 0.06566 (11) | 0.0491 (5) | |
C10 | −0.27836 (19) | 0.3830 (2) | 0.05061 (13) | 0.0647 (7) | |
H10 | −0.3474 | 0.3930 | 0.0377 | 0.078* | |
C11 | −0.2192 (2) | 0.4750 (2) | 0.05443 (14) | 0.0752 (8) | |
H11 | −0.2473 | 0.5504 | 0.0436 | 0.090* | |
C12 | −0.1210 (2) | 0.4630 (2) | 0.07318 (14) | 0.0722 (7) | |
H12 | −0.0804 | 0.5293 | 0.0761 | 0.087* | |
C13 | −0.08068 (17) | 0.35450 (19) | 0.08794 (12) | 0.0552 (6) | |
C14 | −0.09559 (13) | 0.14224 (16) | 0.09883 (9) | 0.0352 (4) | |
C15 | −0.39002 (19) | 0.1817 (3) | 0.0417 (2) | 0.1092 (13) | |
H15A | −0.4099 (5) | 0.237 (2) | 0.0725 (11) | 0.164* | |
H15B | −0.4160 (6) | 0.1048 (17) | 0.0464 (14) | 0.164* | |
H15C | −0.4156 (6) | 0.207 (2) | −0.0092 (11) | 0.164* | |
C16 | 0.0817 (3) | 0.4227 (3) | 0.1170 (2) | 0.1181 (14) | |
H16A | 0.0782 (15) | 0.4693 (18) | 0.1579 (13) | 0.177* | |
H16B | 0.0656 (13) | 0.4706 (18) | 0.0734 (11) | 0.177* | |
H16C | 0.1476 (15) | 0.3922 (7) | 0.1279 (16) | 0.177* | |
N1A | −0.03060 (14) | 0.09627 (16) | 0.30888 (9) | 0.0496 (5) | |
H1A1 | 0.0110 (17) | 0.036 (2) | 0.3226 (12) | 0.061 (7)* | |
H1A2 | −0.0469 (17) | 0.125 (2) | 0.2637 (14) | 0.063 (7)* | |
N2A | −0.04005 (13) | 0.09148 (15) | 0.42044 (9) | 0.0440 (4) | |
H2A1 | −0.0029 (15) | 0.0266 (19) | 0.4282 (11) | 0.051 (6)* | |
H2A2 | −0.0631 (16) | 0.115 (2) | 0.4560 (13) | 0.064 (7)* | |
C1A | −0.12632 (13) | 0.24195 (15) | 0.34031 (9) | 0.0377 (4) | |
C2A | −0.16792 (17) | 0.27778 (18) | 0.27002 (11) | 0.0550 (6) | |
H2A3 | −0.1555 | 0.2362 | 0.2315 | 0.066* | |
C3A | −0.2270 (2) | 0.3725 (2) | 0.25458 (13) | 0.0727 (8) | |
H3A | −0.2562 | 0.3968 | 0.2052 | 0.087* | |
C4A | −0.24465 (19) | 0.4325 (2) | 0.30864 (14) | 0.0695 (7) | |
H4A | −0.2862 | 0.4990 | 0.2975 | 0.083* | |
C5A | −0.20335 (18) | 0.3982 (2) | 0.37838 (13) | 0.0620 (6) | |
H5A | −0.2153 | 0.4412 | 0.4166 | 0.074* | |
C6A | −0.14501 (15) | 0.30321 (18) | 0.39470 (11) | 0.0495 (5) | |
H6A | −0.1169 | 0.2790 | 0.4442 | 0.059* | |
C7A | −0.06351 (13) | 0.13984 (15) | 0.35715 (9) | 0.0344 (4) | |
O1A | 0.08851 (11) | −0.09474 (11) | 0.34245 (7) | 0.0477 (4) | |
O2A | 0.06223 (10) | −0.12115 (11) | 0.44559 (7) | 0.0459 (3) | |
O3A | 0.25262 (11) | −0.25549 (13) | 0.47826 (9) | 0.0638 (4) | |
O4A | −0.04000 (12) | −0.29495 (15) | 0.29483 (9) | 0.0738 (5) | |
C8A | 0.10499 (14) | −0.28187 (16) | 0.38908 (10) | 0.0390 (4) | |
C9A | 0.19058 (15) | −0.33014 (17) | 0.43287 (11) | 0.0461 (5) | |
C10A | 0.20891 (19) | −0.4456 (2) | 0.42869 (14) | 0.0643 (6) | |
H10A | 0.2683 | −0.4790 | 0.4597 | 0.077* | |
C11A | 0.1415 (2) | −0.5118 (2) | 0.37979 (16) | 0.0798 (8) | |
H11A | 0.1535 | −0.5929 | 0.3774 | 0.096* | |
C12A | 0.0574 (2) | −0.4663 (2) | 0.33399 (15) | 0.0762 (8) | |
H12A | 0.0111 | −0.5141 | 0.2993 | 0.091* | |
C13A | 0.04010 (16) | −0.35059 (18) | 0.33850 (12) | 0.0540 (5) | |
C14A | 0.08406 (12) | −0.15605 (15) | 0.39317 (9) | 0.0340 (4) | |
C15A | 0.34956 (18) | −0.2927 (2) | 0.51199 (17) | 0.0819 (8) | |
H15D | 0.3773 (7) | −0.3192 (17) | 0.4742 (6) | 0.123* | |
H15E | 0.3505 (2) | −0.3577 (16) | 0.5457 (10) | 0.123* | |
H15F | 0.3892 (8) | −0.2275 (12) | 0.5398 (10) | 0.123* | |
C16A | −0.0970 (2) | −0.3497 (3) | 0.23207 (17) | 0.0950 (10) | |
H16D | −0.1438 (14) | −0.2944 (11) | 0.2015 (8) | 0.143* | |
H16E | −0.1323 (14) | −0.4139 (17) | 0.2448 (3) | 0.143* | |
H16F | −0.0553 (8) | −0.3794 (18) | 0.2055 (8) | 0.143* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0567 (11) | 0.0485 (10) | 0.0307 (9) | 0.0184 (9) | 0.0186 (8) | 0.0060 (8) |
N2 | 0.0488 (10) | 0.0528 (10) | 0.0309 (8) | 0.0144 (8) | 0.0164 (8) | 0.0074 (8) |
C1 | 0.0415 (10) | 0.0392 (10) | 0.0343 (10) | 0.0026 (8) | 0.0157 (8) | 0.0010 (8) |
C2 | 0.0752 (16) | 0.0860 (17) | 0.0402 (12) | 0.0412 (14) | 0.0243 (11) | 0.0112 (12) |
C3 | 0.099 (2) | 0.120 (2) | 0.0519 (14) | 0.0678 (19) | 0.0286 (15) | 0.0290 (15) |
C4 | 0.0754 (17) | 0.0763 (17) | 0.0750 (17) | 0.0401 (14) | 0.0369 (14) | 0.0194 (14) |
C5 | 0.0802 (17) | 0.0654 (15) | 0.0630 (15) | 0.0240 (13) | 0.0376 (13) | −0.0042 (12) |
C6 | 0.0672 (14) | 0.0586 (13) | 0.0387 (11) | 0.0166 (11) | 0.0211 (10) | 0.0006 (10) |
C7 | 0.0364 (9) | 0.0368 (9) | 0.0277 (9) | −0.0015 (8) | 0.0101 (7) | −0.0026 (7) |
O1 | 0.0754 (10) | 0.0533 (8) | 0.0298 (7) | 0.0258 (7) | 0.0218 (7) | 0.0097 (6) |
O2 | 0.0641 (9) | 0.0474 (8) | 0.0301 (7) | 0.0174 (7) | 0.0172 (6) | 0.0016 (6) |
O3 | 0.0472 (9) | 0.0626 (10) | 0.1058 (14) | 0.0119 (8) | 0.0250 (9) | 0.0152 (10) |
O4 | 0.0628 (11) | 0.0574 (10) | 0.1257 (16) | −0.0100 (9) | 0.0227 (11) | −0.0006 (10) |
C8 | 0.0550 (12) | 0.0392 (10) | 0.0258 (9) | 0.0085 (9) | 0.0144 (8) | 0.0022 (8) |
C9 | 0.0556 (13) | 0.0502 (12) | 0.0414 (11) | 0.0154 (10) | 0.0159 (10) | 0.0049 (9) |
C10 | 0.0701 (16) | 0.0607 (15) | 0.0587 (14) | 0.0304 (13) | 0.0149 (12) | 0.0070 (12) |
C11 | 0.106 (2) | 0.0473 (14) | 0.0655 (16) | 0.0296 (15) | 0.0194 (15) | 0.0064 (12) |
C12 | 0.101 (2) | 0.0397 (13) | 0.0734 (17) | 0.0017 (13) | 0.0243 (15) | 0.0010 (12) |
C13 | 0.0663 (15) | 0.0472 (12) | 0.0495 (12) | 0.0051 (11) | 0.0154 (11) | 0.0010 (10) |
C14 | 0.0382 (10) | 0.0400 (10) | 0.0285 (9) | 0.0060 (8) | 0.0126 (8) | 0.0030 (8) |
C15 | 0.0492 (16) | 0.104 (2) | 0.174 (4) | 0.0153 (16) | 0.0370 (19) | 0.022 (2) |
C16 | 0.092 (2) | 0.090 (2) | 0.161 (4) | −0.033 (2) | 0.026 (2) | −0.008 (2) |
N1A | 0.0699 (12) | 0.0519 (10) | 0.0312 (9) | 0.0242 (10) | 0.0223 (8) | 0.0069 (8) |
N2A | 0.0607 (11) | 0.0437 (10) | 0.0306 (9) | 0.0151 (9) | 0.0191 (8) | 0.0038 (7) |
C1A | 0.0441 (10) | 0.0356 (10) | 0.0348 (10) | 0.0009 (8) | 0.0150 (8) | −0.0009 (8) |
C2A | 0.0788 (15) | 0.0495 (12) | 0.0382 (11) | 0.0196 (11) | 0.0210 (11) | 0.0047 (9) |
C3A | 0.101 (2) | 0.0633 (15) | 0.0506 (13) | 0.0349 (14) | 0.0212 (13) | 0.0172 (12) |
C4A | 0.0853 (18) | 0.0506 (13) | 0.0767 (17) | 0.0307 (13) | 0.0321 (14) | 0.0128 (12) |
C5A | 0.0806 (17) | 0.0519 (13) | 0.0614 (14) | 0.0179 (12) | 0.0342 (13) | −0.0037 (11) |
C6A | 0.0618 (13) | 0.0488 (12) | 0.0408 (11) | 0.0124 (10) | 0.0207 (10) | −0.0009 (9) |
C7A | 0.0397 (10) | 0.0357 (9) | 0.0282 (9) | 0.0002 (8) | 0.0115 (8) | −0.0022 (7) |
O1A | 0.0716 (10) | 0.0423 (7) | 0.0379 (7) | 0.0150 (7) | 0.0299 (7) | 0.0098 (6) |
O2A | 0.0665 (9) | 0.0450 (8) | 0.0323 (7) | 0.0154 (7) | 0.0246 (6) | 0.0035 (6) |
O3A | 0.0533 (9) | 0.0563 (9) | 0.0671 (10) | 0.0168 (7) | −0.0003 (8) | −0.0038 (8) |
O4A | 0.0683 (11) | 0.0666 (10) | 0.0649 (10) | 0.0100 (9) | −0.0074 (8) | −0.0177 (9) |
C8A | 0.0499 (11) | 0.0384 (10) | 0.0334 (9) | 0.0065 (9) | 0.0202 (9) | 0.0019 (8) |
C9A | 0.0544 (12) | 0.0431 (11) | 0.0428 (11) | 0.0127 (10) | 0.0186 (10) | 0.0050 (9) |
C10A | 0.0732 (16) | 0.0490 (13) | 0.0703 (15) | 0.0239 (12) | 0.0232 (13) | 0.0100 (12) |
C11A | 0.103 (2) | 0.0378 (13) | 0.097 (2) | 0.0138 (14) | 0.0305 (18) | −0.0053 (13) |
C12A | 0.0861 (19) | 0.0474 (14) | 0.0850 (18) | −0.0016 (13) | 0.0141 (15) | −0.0186 (13) |
C13A | 0.0612 (14) | 0.0479 (12) | 0.0516 (12) | 0.0063 (10) | 0.0165 (11) | −0.0063 (10) |
C14A | 0.0377 (10) | 0.0381 (10) | 0.0268 (9) | 0.0066 (8) | 0.0114 (7) | 0.0010 (8) |
C15A | 0.0538 (15) | 0.0728 (17) | 0.103 (2) | 0.0125 (13) | 0.0030 (14) | 0.0060 (16) |
C16A | 0.086 (2) | 0.088 (2) | 0.084 (2) | −0.0080 (17) | −0.0094 (16) | −0.0218 (17) |
Geometric parameters (Å, º) top
N1—C7 | 1.310 (2) | N1A—C7A | 1.305 (2) |
N1—H1A | 0.92 (2) | N1A—H1A1 | 0.92 (2) |
N1—H1B | 0.90 (3) | N1A—H1A2 | 0.91 (3) |
N2—C7 | 1.310 (2) | N2A—C7A | 1.310 (2) |
N2—H2A | 0.95 (2) | N2A—H2A1 | 0.92 (2) |
N2—H2B | 0.93 (2) | N2A—H2A2 | 0.92 (3) |
C1—C2 | 1.380 (3) | C1A—C2A | 1.385 (3) |
C1—C6 | 1.384 (3) | C1A—C6A | 1.391 (3) |
C1—C7 | 1.479 (3) | C1A—C7A | 1.481 (3) |
C2—C3 | 1.383 (3) | C2A—C3A | 1.381 (3) |
C2—H2 | 0.9700 | C2A—H2A3 | 0.9700 |
C3—C4 | 1.372 (4) | C3A—C4A | 1.371 (3) |
C3—H3 | 0.9700 | C3A—H3A | 0.9700 |
C4—C5 | 1.359 (3) | C4A—C5A | 1.370 (3) |
C4—H4 | 0.9700 | C4A—H4A | 0.9700 |
C5—C6 | 1.380 (3) | C5A—C6A | 1.378 (3) |
C5—H5 | 0.9700 | C5A—H5A | 0.9700 |
C6—H6 | 0.9700 | C6A—H6A | 0.9700 |
O1—C14 | 1.246 (2) | O1A—C14A | 1.251 (2) |
O2—C14 | 1.251 (2) | O2A—C14A | 1.248 (2) |
O3—C9 | 1.366 (3) | O3A—C9A | 1.365 (3) |
O3—C15 | 1.421 (3) | O3A—C15A | 1.430 (3) |
O4—C13 | 1.370 (3) | O4A—C13A | 1.375 (3) |
O4—C16 | 1.419 (3) | O4A—C16A | 1.402 (3) |
C8—C9 | 1.386 (3) | C8A—C13A | 1.389 (3) |
C8—C13 | 1.387 (3) | C8A—C9A | 1.392 (3) |
C8—C14 | 1.508 (3) | C8A—C14A | 1.514 (3) |
C9—C10 | 1.389 (3) | C9A—C10A | 1.387 (3) |
C10—C11 | 1.372 (4) | C10A—C11A | 1.374 (4) |
C10—H10 | 0.9700 | C10A—H10A | 0.9700 |
C11—C12 | 1.375 (4) | C11A—C12A | 1.378 (4) |
C11—H11 | 0.9700 | C11A—H11A | 0.9700 |
C12—C13 | 1.393 (3) | C12A—C13A | 1.387 (3) |
C12—H12 | 0.9700 | C12A—H12A | 0.9700 |
C15—H15A | 0.9946 | C15A—H15D | 1.0080 |
C15—H15B | 0.9946 | C15A—H15E | 1.0080 |
C15—H15C | 0.9946 | C15A—H15F | 1.0080 |
C16—H16A | 0.9886 | C16A—H16D | 0.9925 |
C16—H16B | 0.9886 | C16A—H16E | 0.9925 |
C16—H16C | 0.9886 | C16A—H16F | 0.9925 |
| | | |
C7—N1—H1A | 117.0 (14) | C7A—N1A—H1A1 | 117.3 (14) |
C7—N1—H1B | 121.7 (15) | C7A—N1A—H1A2 | 121.7 (15) |
H1A—N1—H1B | 120 (2) | H1A1—N1A—H1A2 | 121 (2) |
C7—N2—H2A | 117.5 (12) | C7A—N2A—H2A1 | 118.2 (13) |
C7—N2—H2B | 122.8 (14) | C7A—N2A—H2A2 | 123.3 (15) |
H2A—N2—H2B | 119.6 (19) | H2A1—N2A—H2A2 | 118 (2) |
C2—C1—C6 | 119.12 (18) | C2A—C1A—C6A | 118.80 (18) |
C2—C1—C7 | 119.83 (16) | C2A—C1A—C7A | 120.53 (16) |
C6—C1—C7 | 121.04 (17) | C6A—C1A—C7A | 120.68 (16) |
C1—C2—C3 | 119.9 (2) | C3A—C2A—C1A | 120.3 (2) |
C1—C2—H2 | 120.1 | C3A—C2A—H2A3 | 119.9 |
C3—C2—H2 | 120.1 | C1A—C2A—H2A3 | 119.9 |
C4—C3—C2 | 120.4 (2) | C4A—C3A—C2A | 120.4 (2) |
C4—C3—H3 | 119.8 | C4A—C3A—H3A | 119.8 |
C2—C3—H3 | 119.8 | C2A—C3A—H3A | 119.8 |
C5—C4—C3 | 119.9 (2) | C5A—C4A—C3A | 119.7 (2) |
C5—C4—H4 | 120.0 | C5A—C4A—H4A | 120.1 |
C3—C4—H4 | 120.0 | C3A—C4A—H4A | 120.1 |
C4—C5—C6 | 120.5 (2) | C4A—C5A—C6A | 120.6 (2) |
C4—C5—H5 | 119.8 | C4A—C5A—H5A | 119.7 |
C6—C5—H5 | 119.8 | C6A—C5A—H5A | 119.7 |
C5—C6—C1 | 120.2 (2) | C5A—C6A—C1A | 120.14 (19) |
C5—C6—H6 | 119.9 | C5A—C6A—H6A | 119.9 |
C1—C6—H6 | 119.9 | C1A—C6A—H6A | 119.9 |
N1—C7—N2 | 118.95 (18) | N1A—C7A—N2A | 118.76 (18) |
N1—C7—C1 | 120.66 (16) | N1A—C7A—C1A | 120.36 (16) |
N2—C7—C1 | 120.39 (16) | N2A—C7A—C1A | 120.88 (16) |
C9—O3—C15 | 118.9 (2) | C9A—O3A—C15A | 117.38 (18) |
C13—O4—C16 | 119.0 (2) | C13A—O4A—C16A | 118.5 (2) |
C9—C8—C13 | 119.14 (18) | C13A—C8A—C9A | 118.60 (18) |
C9—C8—C14 | 120.48 (18) | C13A—C8A—C14A | 119.93 (17) |
C13—C8—C14 | 120.37 (18) | C9A—C8A—C14A | 121.40 (17) |
O3—C9—C8 | 114.31 (17) | O3A—C9A—C10A | 124.2 (2) |
O3—C9—C10 | 124.7 (2) | O3A—C9A—C8A | 114.88 (17) |
C8—C9—C10 | 121.0 (2) | C10A—C9A—C8A | 120.9 (2) |
C11—C10—C9 | 118.7 (2) | C11A—C10A—C9A | 118.9 (2) |
C11—C10—H10 | 120.6 | C11A—C10A—H10A | 120.6 |
C9—C10—H10 | 120.6 | C9A—C10A—H10A | 120.6 |
C10—C11—C12 | 121.7 (2) | C10A—C11A—C12A | 121.8 (2) |
C10—C11—H11 | 119.1 | C10A—C11A—H11A | 119.1 |
C12—C11—H11 | 119.1 | C12A—C11A—H11A | 119.1 |
C11—C12—C13 | 119.1 (2) | C11A—C12A—C13A | 118.7 (2) |
C11—C12—H12 | 120.4 | C11A—C12A—H12A | 120.7 |
C13—C12—H12 | 120.4 | C13A—C12A—H12A | 120.7 |
O4—C13—C8 | 114.87 (19) | O4A—C13A—C12A | 124.1 (2) |
O4—C13—C12 | 124.8 (2) | O4A—C13A—C8A | 114.90 (18) |
C8—C13—C12 | 120.3 (2) | C12A—C13A—C8A | 121.0 (2) |
O1—C14—O2 | 124.56 (17) | O2A—C14A—O1A | 124.75 (16) |
O1—C14—C8 | 118.12 (15) | O2A—C14A—C8A | 118.39 (15) |
O2—C14—C8 | 117.31 (15) | O1A—C14A—C8A | 116.85 (15) |
O3—C15—H15A | 109.5 | O3A—C15A—H15D | 109.5 |
O3—C15—H15B | 109.5 | O3A—C15A—H15E | 109.5 |
H15A—C15—H15B | 109.5 | H15D—C15A—H15E | 109.5 |
O3—C15—H15C | 109.5 | O3A—C15A—H15F | 109.5 |
H15A—C15—H15C | 109.5 | H15D—C15A—H15F | 109.5 |
H15B—C15—H15C | 109.5 | H15E—C15A—H15F | 109.5 |
O4—C16—H16A | 109.5 | O4A—C16A—H16D | 109.5 |
O4—C16—H16B | 109.5 | O4A—C16A—H16E | 109.5 |
H16A—C16—H16B | 109.5 | H16D—C16A—H16E | 109.5 |
O4—C16—H16C | 109.5 | O4A—C16A—H16F | 109.5 |
H16A—C16—H16C | 109.5 | H16D—C16A—H16F | 109.5 |
H16B—C16—H16C | 109.5 | H16E—C16A—H16F | 109.5 |
| | | |
C6—C1—C2—C3 | −0.4 (4) | C6A—C1A—C2A—C3A | −0.1 (3) |
C7—C1—C2—C3 | −179.6 (2) | C7A—C1A—C2A—C3A | 179.5 (2) |
C1—C2—C3—C4 | 0.2 (5) | C1A—C2A—C3A—C4A | 0.4 (4) |
C2—C3—C4—C5 | 0.3 (5) | C2A—C3A—C4A—C5A | 0.0 (4) |
C3—C4—C5—C6 | −0.6 (5) | C3A—C4A—C5A—C6A | −0.7 (4) |
C4—C5—C6—C1 | 0.4 (4) | C4A—C5A—C6A—C1A | 0.9 (4) |
C2—C1—C6—C5 | 0.1 (3) | C2A—C1A—C6A—C5A | −0.5 (3) |
C7—C1—C6—C5 | 179.3 (2) | C7A—C1A—C6A—C5A | 179.8 (2) |
C2—C1—C7—N1 | −20.8 (3) | C2A—C1A—C7A—N1A | 14.1 (3) |
C6—C1—C7—N1 | 160.0 (2) | C6A—C1A—C7A—N1A | −166.25 (19) |
C2—C1—C7—N2 | 159.5 (2) | C2A—C1A—C7A—N2A | −165.8 (2) |
C6—C1—C7—N2 | −19.7 (3) | C6A—C1A—C7A—N2A | 13.9 (3) |
C15—O3—C9—C8 | −176.9 (2) | C15A—O3A—C9A—C10A | 14.0 (3) |
C15—O3—C9—C10 | 3.1 (4) | C15A—O3A—C9A—C8A | −165.6 (2) |
C13—C8—C9—O3 | −179.92 (18) | C13A—C8A—C9A—O3A | 176.49 (18) |
C14—C8—C9—O3 | 1.4 (3) | C14A—C8A—C9A—O3A | −0.5 (3) |
C13—C8—C9—C10 | 0.1 (3) | C13A—C8A—C9A—C10A | −3.1 (3) |
C14—C8—C9—C10 | −178.58 (18) | C14A—C8A—C9A—C10A | 179.93 (19) |
O3—C9—C10—C11 | −179.9 (2) | O3A—C9A—C10A—C11A | −178.8 (2) |
C8—C9—C10—C11 | 0.1 (3) | C8A—C9A—C10A—C11A | 0.8 (3) |
C9—C10—C11—C12 | −0.5 (4) | C9A—C10A—C11A—C12A | 1.3 (4) |
C10—C11—C12—C13 | 0.7 (4) | C10A—C11A—C12A—C13A | −1.0 (5) |
C16—O4—C13—C8 | −174.1 (3) | C16A—O4A—C13A—C12A | −15.1 (4) |
C16—O4—C13—C12 | 7.0 (4) | C16A—O4A—C13A—C8A | 164.8 (2) |
C9—C8—C13—O4 | −178.76 (19) | C11A—C12A—C13A—O4A | 178.6 (3) |
C14—C8—C13—O4 | −0.1 (3) | C11A—C12A—C13A—C8A | −1.4 (4) |
C9—C8—C13—C12 | 0.1 (3) | C9A—C8A—C13A—O4A | −176.55 (18) |
C14—C8—C13—C12 | 178.79 (19) | C14A—C8A—C13A—O4A | 0.5 (3) |
C11—C12—C13—O4 | 178.3 (2) | C9A—C8A—C13A—C12A | 3.4 (3) |
C11—C12—C13—C8 | −0.5 (4) | C14A—C8A—C13A—C12A | −179.6 (2) |
C9—C8—C14—O1 | −88.9 (2) | C13A—C8A—C14A—O2A | 108.7 (2) |
C13—C8—C14—O1 | 92.5 (2) | C9A—C8A—C14A—O2A | −74.3 (2) |
C9—C8—C14—O2 | 90.2 (2) | C13A—C8A—C14A—O1A | −70.1 (2) |
C13—C8—C14—O2 | −88.4 (2) | C9A—C8A—C14A—O1A | 106.8 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1 | 0.92 (2) | 1.89 (3) | 2.799 (2) | 171 (2) |
N1—H1B···O1A | 0.90 (3) | 2.03 (3) | 2.827 (2) | 148 (2) |
N2—H2A···O2 | 0.95 (2) | 1.85 (2) | 2.796 (2) | 176.3 (19) |
N2—H2B···O2i | 0.93 (2) | 1.93 (2) | 2.763 (2) | 148.7 (19) |
N1A—H1A1···O1A | 0.92 (2) | 1.87 (3) | 2.785 (2) | 175 (2) |
N1A—H1A2···O1 | 0.91 (3) | 1.95 (3) | 2.773 (2) | 150 (2) |
N2A—H2A1···O2A | 0.92 (2) | 1.95 (2) | 2.868 (2) | 173.0 (19) |
N2A—H2A2···O2Aii | 0.92 (3) | 1.94 (3) | 2.789 (2) | 153 (2) |
Symmetry codes: (i) −x, −y, −z; (ii) −x, −y, −z+1. |
(II) Benzamidinidium 2,6-dimethoxybenzoate
top
Crystal data top
C7H9N2+·C9H9O4− | F(000) = 640 |
Mr = 302.32 | Dx = 1.283 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 116123 reflections |
a = 9.8921 (1) Å | θ = 2.8–32.6° |
b = 10.4471 (1) Å | µ = 0.09 mm−1 |
c = 15.1403 (2) Å | T = 298 K |
V = 1564.65 (3) Å3 | Small prism, colourless |
Z = 4 | 0.20 × 0.15 × 0.12 mm |
Data collection top
Oxford Xcalibur S CCD area-detector diffractometer | 3175 independent reflections |
Radiation source: Enhance (Mo) X-ray source | 2872 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.040 |
Detector resolution: 16.0696 pixels mm-1 | θmax = 32.6°, θmin = 2.8° |
ω and ϕ scans | h = −15→14 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008) | k = −15→15 |
Tmin = 0.935, Tmax = 0.986 | l = −22→22 |
327892 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)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.156 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.19 | w = 1/[σ2(Fo2) + (0.0886P)2 + 0.1272P] where P = (Fo2 + 2Fc2)/3 |
3175 reflections | (Δ/σ)max < 0.001 |
219 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
Crystal data top
C7H9N2+·C9H9O4− | V = 1564.65 (3) Å3 |
Mr = 302.32 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 9.8921 (1) Å | µ = 0.09 mm−1 |
b = 10.4471 (1) Å | T = 298 K |
c = 15.1403 (2) Å | 0.20 × 0.15 × 0.12 mm |
Data collection top
Oxford Xcalibur S CCD area-detector diffractometer | 3175 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008) | 2872 reflections with I > 2σ(I) |
Tmin = 0.935, Tmax = 0.986 | Rint = 0.040 |
327892 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.058 | 0 restraints |
wR(F2) = 0.156 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.19 | Δρmax = 0.30 e Å−3 |
3175 reflections | Δρmin = −0.18 e Å−3 |
219 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 >
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 | Uiso*/Ueq | |
N1 | 0.24030 (16) | 0.15399 (19) | −0.03437 (12) | 0.0400 (4) | |
H1A | 0.248 (2) | 0.225 (2) | 0.0091 (16) | 0.034 (6)* | |
H1B | 0.165 (3) | 0.130 (3) | −0.0539 (19) | 0.043 (7)* | |
N2 | 0.46956 (16) | 0.1472 (2) | −0.03504 (13) | 0.0420 (4) | |
H2A | 0.468 (3) | 0.209 (3) | 0.002 (2) | 0.051 (8)* | |
H2B | 0.557 (3) | 0.112 (3) | −0.048 (2) | 0.051 (8)* | |
C1 | 0.34893 (17) | 0.00992 (15) | −0.13753 (11) | 0.0301 (3) | |
C2 | 0.2336 (2) | −0.0641 (2) | −0.14905 (17) | 0.0479 (5) | |
H2 | 0.1576 | −0.0543 | −0.1091 | 0.058* | |
C3 | 0.2269 (3) | −0.1521 (3) | −0.21747 (19) | 0.0569 (6) | |
H3 | 0.1463 | −0.2038 | −0.2253 | 0.068* | |
C4 | 0.3339 (3) | −0.1663 (3) | −0.27409 (18) | 0.0577 (6) | |
H4 | 0.3286 | −0.2270 | −0.3224 | 0.069* | |
C5 | 0.4486 (3) | −0.0945 (3) | −0.26236 (19) | 0.0663 (8) | |
H5 | 0.5244 | −0.1057 | −0.3023 | 0.080* | |
C6 | 0.4578 (2) | −0.0058 (2) | −0.19409 (16) | 0.0501 (6) | |
H6 | 0.5394 | 0.0444 | −0.1862 | 0.060* | |
C7 | 0.35372 (17) | 0.10679 (16) | −0.06615 (12) | 0.0299 (3) | |
O1 | 0.24645 (12) | 0.37862 (14) | 0.06668 (10) | 0.0377 (3) | |
O2 | 0.46808 (13) | 0.35660 (15) | 0.08260 (12) | 0.0438 (4) | |
O3 | 0.4554 (2) | 0.6099 (2) | −0.02050 (12) | 0.0595 (5) | |
O4 | 0.2968 (2) | 0.4922 (2) | 0.25686 (10) | 0.0552 (5) | |
C8 | 0.36935 (16) | 0.55819 (17) | 0.11803 (12) | 0.0318 (3) | |
C9 | 0.4143 (2) | 0.6527 (2) | 0.06053 (15) | 0.0420 (4) | |
C10 | 0.4192 (3) | 0.7809 (2) | 0.0872 (2) | 0.0575 (6) | |
H10 | 0.4480 | 0.8471 | 0.0464 | 0.069* | |
C11 | 0.3826 (3) | 0.8113 (2) | 0.1723 (3) | 0.0680 (8) | |
H11 | 0.3857 | 0.9000 | 0.1910 | 0.082* | |
C12 | 0.3416 (3) | 0.7191 (3) | 0.23192 (19) | 0.0595 (7) | |
H12 | 0.3179 | 0.7424 | 0.2920 | 0.071* | |
C13 | 0.3349 (2) | 0.5912 (2) | 0.20401 (15) | 0.0410 (4) | |
C14 | 0.36127 (16) | 0.42050 (16) | 0.08702 (10) | 0.0286 (3) | |
C15 | 0.5270 (4) | 0.6947 (4) | −0.0758 (3) | 0.0815 (10) | |
H15A | 0.466 (2) | 0.767 (3) | −0.094 (2) | 0.122* | |
H15B | 0.559 (3) | 0.6477 (16) | −0.1298 (18) | 0.122* | |
H15C | 0.607 (3) | 0.730 (3) | −0.0430 (12) | 0.122* | |
C16 | 0.2997 (3) | 0.5119 (4) | 0.35037 (17) | 0.0696 (8) | |
H16A | 0.227 (2) | 0.572 (3) | 0.3672 (5) | 0.104* | |
H16B | 0.388 (3) | 0.548 (2) | 0.3676 (5) | 0.104* | |
H16C | 0.285 (3) | 0.430 (2) | 0.3808 (8) | 0.104* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0227 (6) | 0.0471 (9) | 0.0502 (9) | 0.0013 (6) | −0.0006 (6) | −0.0191 (8) |
N2 | 0.0240 (7) | 0.0473 (9) | 0.0546 (10) | 0.0006 (6) | −0.0022 (6) | −0.0209 (9) |
C1 | 0.0274 (7) | 0.0274 (6) | 0.0354 (7) | −0.0009 (6) | 0.0000 (6) | −0.0047 (6) |
C2 | 0.0304 (8) | 0.0466 (11) | 0.0668 (13) | −0.0078 (8) | 0.0030 (9) | −0.0205 (11) |
C3 | 0.0455 (11) | 0.0490 (12) | 0.0762 (16) | −0.0064 (10) | −0.0115 (11) | −0.0253 (13) |
C4 | 0.0728 (16) | 0.0485 (12) | 0.0518 (12) | −0.0024 (12) | −0.0034 (12) | −0.0192 (10) |
C5 | 0.0710 (16) | 0.0700 (17) | 0.0579 (14) | −0.0136 (15) | 0.0275 (13) | −0.0268 (13) |
C6 | 0.0439 (10) | 0.0511 (12) | 0.0552 (12) | −0.0135 (10) | 0.0188 (10) | −0.0166 (10) |
C7 | 0.0247 (6) | 0.0285 (7) | 0.0366 (7) | −0.0007 (6) | 0.0010 (6) | −0.0042 (6) |
O1 | 0.0240 (5) | 0.0409 (7) | 0.0481 (7) | −0.0046 (5) | −0.0001 (5) | −0.0131 (6) |
O2 | 0.0260 (6) | 0.0437 (7) | 0.0617 (9) | 0.0014 (5) | −0.0011 (6) | −0.0191 (7) |
O3 | 0.0740 (12) | 0.0593 (10) | 0.0451 (8) | −0.0179 (10) | 0.0083 (8) | 0.0012 (7) |
O4 | 0.0642 (11) | 0.0634 (10) | 0.0380 (7) | −0.0107 (9) | 0.0119 (7) | −0.0117 (7) |
C8 | 0.0225 (6) | 0.0339 (7) | 0.0392 (8) | −0.0014 (6) | −0.0016 (6) | −0.0094 (7) |
C9 | 0.0365 (9) | 0.0407 (9) | 0.0486 (10) | −0.0029 (8) | −0.0056 (8) | −0.0022 (8) |
C10 | 0.0570 (14) | 0.0361 (10) | 0.0795 (17) | −0.0045 (10) | −0.0055 (13) | −0.0004 (11) |
C11 | 0.0660 (17) | 0.0393 (11) | 0.099 (2) | 0.0001 (12) | 0.0005 (16) | −0.0243 (13) |
C12 | 0.0561 (14) | 0.0564 (13) | 0.0662 (14) | 0.0015 (11) | 0.0068 (12) | −0.0340 (12) |
C13 | 0.0323 (8) | 0.0453 (10) | 0.0454 (9) | −0.0015 (7) | 0.0034 (7) | −0.0175 (8) |
C14 | 0.0242 (6) | 0.0333 (7) | 0.0283 (6) | −0.0026 (6) | 0.0034 (6) | −0.0067 (6) |
C15 | 0.096 (2) | 0.077 (2) | 0.0720 (19) | −0.017 (2) | 0.0219 (19) | 0.0166 (17) |
C16 | 0.0728 (18) | 0.097 (2) | 0.0388 (11) | 0.0119 (18) | 0.0022 (11) | −0.0101 (13) |
Geometric parameters (Å, º) top
N1—C7 | 1.317 (2) | O3—C9 | 1.368 (3) |
N1—H1A | 1.00 (3) | O3—C15 | 1.410 (4) |
N1—H1B | 0.84 (3) | O4—C13 | 1.361 (3) |
N2—C7 | 1.309 (2) | O4—C16 | 1.431 (3) |
N2—H2A | 0.86 (3) | C8—C13 | 1.389 (3) |
N2—H2B | 0.96 (3) | C8—C9 | 1.389 (3) |
C1—C6 | 1.386 (3) | C8—C14 | 1.515 (2) |
C1—C2 | 1.389 (3) | C9—C10 | 1.400 (3) |
C1—C7 | 1.481 (2) | C10—C11 | 1.376 (5) |
C2—C3 | 1.387 (3) | C10—H10 | 0.9700 |
C2—H2 | 0.9700 | C11—C12 | 1.380 (5) |
C3—C4 | 1.370 (4) | C11—H11 | 0.9700 |
C3—H3 | 0.9700 | C12—C13 | 1.403 (3) |
C4—C5 | 1.371 (4) | C12—H12 | 0.9700 |
C4—H4 | 0.9700 | C15—H15A | 1.0051 |
C5—C6 | 1.391 (3) | C15—H15B | 1.0051 |
C5—H5 | 0.9700 | C15—H15C | 1.0051 |
C6—H6 | 0.9700 | C16—H16A | 0.9863 |
O1—C14 | 1.255 (2) | C16—H16B | 0.9863 |
O2—C14 | 1.252 (2) | C16—H16C | 0.9863 |
| | | |
C7—N1—H1A | 117.3 (14) | C9—C8—C14 | 119.81 (16) |
C7—N1—H1B | 121 (2) | O3—C9—C8 | 115.16 (19) |
H1A—N1—H1B | 121 (2) | O3—C9—C10 | 124.1 (2) |
C7—N2—H2A | 117 (2) | C8—C9—C10 | 120.7 (2) |
C7—N2—H2B | 126.0 (19) | C11—C10—C9 | 118.8 (3) |
H2A—N2—H2B | 116 (3) | C11—C10—H10 | 120.6 |
C6—C1—C2 | 119.64 (17) | C9—C10—H10 | 120.6 |
C6—C1—C7 | 120.47 (16) | C10—C11—C12 | 121.9 (2) |
C2—C1—C7 | 119.88 (16) | C10—C11—H11 | 119.0 |
C3—C2—C1 | 120.1 (2) | C12—C11—H11 | 119.0 |
C3—C2—H2 | 119.9 | C11—C12—C13 | 118.8 (2) |
C1—C2—H2 | 119.9 | C11—C12—H12 | 120.6 |
C4—C3—C2 | 120.1 (2) | C13—C12—H12 | 120.6 |
C4—C3—H3 | 119.9 | O4—C13—C8 | 115.48 (18) |
C2—C3—H3 | 119.9 | O4—C13—C12 | 124.0 (2) |
C3—C4—C5 | 119.9 (2) | C8—C13—C12 | 120.5 (2) |
C3—C4—H4 | 120.0 | O2—C14—O1 | 124.38 (15) |
C5—C4—H4 | 120.0 | O2—C14—C8 | 118.58 (15) |
C4—C5—C6 | 121.0 (2) | O1—C14—C8 | 117.03 (15) |
C4—C5—H5 | 119.5 | O3—C15—H15A | 109.5 |
C6—C5—H5 | 119.5 | O3—C15—H15B | 109.5 |
C1—C6—C5 | 119.2 (2) | H15A—C15—H15B | 109.5 |
C1—C6—H6 | 120.4 | O3—C15—H15C | 109.5 |
C5—C6—H6 | 120.4 | H15A—C15—H15C | 109.5 |
N2—C7—N1 | 119.58 (15) | H15B—C15—H15C | 109.5 |
N2—C7—C1 | 120.72 (15) | O4—C16—H16A | 109.5 |
N1—C7—C1 | 119.69 (15) | O4—C16—H16B | 109.5 |
C9—O3—C15 | 118.4 (2) | H16A—C16—H16B | 109.5 |
C13—O4—C16 | 117.9 (2) | O4—C16—H16C | 109.5 |
C13—C8—C9 | 119.29 (18) | H16A—C16—H16C | 109.5 |
C13—C8—C14 | 120.88 (17) | H16B—C16—H16C | 109.5 |
| | | |
C6—C1—C2—C3 | −0.8 (4) | C14—C8—C9—C10 | 178.4 (2) |
C7—C1—C2—C3 | 178.0 (2) | O3—C9—C10—C11 | −176.1 (3) |
C1—C2—C3—C4 | −0.1 (4) | C8—C9—C10—C11 | 1.9 (4) |
C2—C3—C4—C5 | 0.9 (5) | C9—C10—C11—C12 | 0.1 (5) |
C3—C4—C5—C6 | −0.7 (5) | C10—C11—C12—C13 | −1.2 (5) |
C2—C1—C6—C5 | 0.9 (4) | C16—O4—C13—C8 | 161.5 (2) |
C7—C1—C6—C5 | −177.8 (2) | C16—O4—C13—C12 | −17.9 (4) |
C4—C5—C6—C1 | −0.2 (5) | C9—C8—C13—O4 | −177.59 (18) |
C6—C1—C7—N2 | −23.6 (3) | C14—C8—C13—O4 | 1.1 (3) |
C2—C1—C7—N2 | 157.6 (2) | C9—C8—C13—C12 | 1.8 (3) |
C6—C1—C7—N1 | 155.5 (2) | C14—C8—C13—C12 | −179.5 (2) |
C2—C1—C7—N1 | −23.3 (3) | C11—C12—C13—O4 | 179.6 (3) |
C15—O3—C9—C8 | −167.5 (3) | C11—C12—C13—C8 | 0.2 (4) |
C15—O3—C9—C10 | 10.7 (4) | C13—C8—C14—O2 | −101.0 (2) |
C13—C8—C9—O3 | 175.32 (18) | C9—C8—C14—O2 | 77.7 (2) |
C14—C8—C9—O3 | −3.4 (3) | C13—C8—C14—O1 | 79.5 (2) |
C13—C8—C9—C10 | −2.9 (3) | C9—C8—C14—O1 | −101.8 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1 | 1.00 (3) | 1.82 (3) | 2.802 (2) | 166 (2) |
N1—H1B···O2i | 0.84 (3) | 2.00 (3) | 2.792 (2) | 157 (3) |
N2—H2B···O1ii | 0.96 (3) | 1.90 (3) | 2.794 (2) | 154 (3) |
N2—H2A···O2 | 0.86 (3) | 1.97 (3) | 2.821 (2) | 177 (3) |
Symmetry codes: (i) x−1/2, −y+1/2, −z; (ii) x+1/2, −y+1/2, −z. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C7H9N2+·C9H9O4− | C7H9N2+·C9H9O4− |
Mr | 302.32 | 302.32 |
Crystal system, space group | Monoclinic, P21/n | Orthorhombic, P212121 |
Temperature (K) | 298 | 298 |
a, b, c (Å) | 14.7103 (2), 11.7174 (1), 19.7281 (3) | 9.8921 (1), 10.4471 (1), 15.1403 (2) |
α, β, γ (°) | 90, 109.145 (2), 90 | 90, 90, 90 |
V (Å3) | 3212.39 (8) | 1564.65 (3) |
Z | 8 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.09 | 0.09 |
Crystal size (mm) | 0.20 × 0.15 × 0.14 | 0.20 × 0.15 × 0.12 |
|
Data collection |
Diffractometer | Oxford Xcalibur S CCD area-detector diffractometer | Oxford Xcalibur S CCD area-detector diffractometer |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | Multi-scan (CrysAlis RED; Oxford Diffraction, 2008) |
Tmin, Tmax | 0.982, 0.987 | 0.935, 0.986 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 248320, 5682, 4978 | 327892, 3175, 2872 |
Rint | 0.041 | 0.040 |
(sin θ/λ)max (Å−1) | 0.596 | 0.759 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.129, 1.18 | 0.058, 0.156, 1.19 |
No. of reflections | 5682 | 3175 |
No. of parameters | 437 | 219 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.18, −0.17 | 0.30, −0.18 |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1 | 0.92 (2) | 1.89 (3) | 2.799 (2) | 171 (2) |
N1—H1B···O1A | 0.90 (3) | 2.03 (3) | 2.827 (2) | 148 (2) |
N2—H2A···O2 | 0.95 (2) | 1.85 (2) | 2.796 (2) | 176.3 (19) |
N2—H2B···O2i | 0.93 (2) | 1.93 (2) | 2.763 (2) | 148.7 (19) |
N1A—H1A1···O1A | 0.92 (2) | 1.87 (3) | 2.785 (2) | 175 (2) |
N1A—H1A2···O1 | 0.91 (3) | 1.95 (3) | 2.773 (2) | 150 (2) |
N2A—H2A1···O2A | 0.92 (2) | 1.95 (2) | 2.868 (2) | 173.0 (19) |
N2A—H2A2···O2Aii | 0.92 (3) | 1.94 (3) | 2.789 (2) | 153 (2) |
Symmetry codes: (i) −x, −y, −z; (ii) −x, −y, −z+1. |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1 | 1.00 (3) | 1.82 (3) | 2.802 (2) | 166 (2) |
N1—H1B···O2i | 0.84 (3) | 2.00 (3) | 2.792 (2) | 157 (3) |
N2—H2B···O1ii | 0.96 (3) | 1.90 (3) | 2.794 (2) | 154 (3) |
N2—H2A···O2 | 0.86 (3) | 1.97 (3) | 2.821 (2) | 177 (3) |
Symmetry codes: (i) x−1/2, −y+1/2, −z; (ii) x+1/2, −y+1/2, −z. |
The present study is a continuation of the design and synthesis of hydrogen-bonding systems formed by benzamidine with benzoic acid derivatives carried out in our laboratory. The protonated analogue of benzamidine is a multiple hydrogen-bond donor, and its amidinium group exhibits ideal requirements to couple with carboxylate groups in crystal structures. These acid–base complexes are usually arranged in a dimeric motif similar to that found in carboxylic acid dimers via N+—H···O- (±)(CAHB) (charge-assisted hydrogen bonds with both plus and minus charges on the donor and acceptor atoms, respectively; Gilli & Gilli, 2009), provided that ΔpKa is sufficiently large [ΔpKa = pKa(conjugate acid of the base) - pKa(acid), where the pKa's are for aqueous solutions at 298 K]. It is generally accepted that, for large ΔpKa (i.e. greater than 3), salts of the type B+···A- are formed, while with smaller ΔpKa B···H—A compounds (cocrystals) can be expected, but this parameter seems inappropriate for accurately predicting salt or cocrystal formation in the solid state when ΔpKa is between 0 and 3 (Portalone & Colapietro, 2009; Portalone, 2011a; Delori et al., 2012). This dimeric motif is commonly observed in biological systems between arginine and aspartic and glutamic acids (Saenger, 1984).
In this study, we report the molecular and supramolecular structures of two concomitant polymorphs, i.e. two different polymorphs simultaneously crystallized from the same solvent (Bernstein et al., 1999), of the acid–base complex formed by benzamidine (Benzam) with 2,6-dimethoxybenzoic acid (Dmb). Interestingly, Dmb has two polymorphic modifications: the orthorhombic form (Portalone, 2009) and the tetragonal form (Portalone, 2011b). In the former polymorph, the carboxyl group is twisted away from the plane of the aromatic ring by 56.1 (1)° and the OH group adopts an antiplanar conformation, while in the latter the twist angle is 65.7 (2)° and the OH group is synplanar. The molecular components of the orthorhombic polymorph do not form the conventional R22(8) dimeric units [see Etter et al. (1990), Bernstein et al. (1995) and Motherwell et al. (1999) for graph-set nomenclature of hydrogen bonds] as they do in the tetragonal polymorph, but are associated in the crystal structure as catemers through single O—H···O(carbonyl) hydrogen bonds between adjacent molecules. As the observation of polymorphism in multi-component systems such as cocrystals and molecular salts is scant, although of topical interest given the growing relevance of pharmaceutical cocrystals (Tiekink & Vittal, 2006), we have been attracted by the planned synthesis of polymorphic molecular salts resulting from the combination of two conformationally flexible molecules, such as Dmb and benzamidine. For BenzamH+Dmb-, since ΔpKa = 7.5, the salt is expected. Indeed, in this proton-transfer compound protonation occurs at the imino N atom attached to Benzam as a result of proton transfer from the acidic hydroxyl group of Dmb.
Polymorph (I) crystallizes in the monoclinic space group P21/n, with two crystallographically independent dimers of monoprotonated benzamidinium cations (BenzamH+) and benzoate anions (Dmb-) in the asymmetric unit (Fig. 1). Polymorph (II) crystallizes in the orthorhombic space group P212121, with one BenzamH+ cation and one Dmb- anion in the asymmetric unit (Fig. 2).
The molecular structures of polymorphs (I) and (II) are very similar. In both polymorphic forms, the BenzamH+ cations are not planar. The dihedral angles between the mean plane of the benzene ring and the amidinium group [20.2 (1) and 14.4 (1)° for polymorph (I), and 23.6 (1)° for polymorph (II)] are close to the values observed in benzamidine [22.7 (1)°; Barker et al., 1996], benzamidinium (2-acetamidobenzoyl)formate [16 (3)°; Joshi et al., 1994] and benzamidinium acetylsalicylate [15.2 (2)°; Kolev et al., 2009). For both polymorphs this disposition is a consequence of an overcrowding effect, i.e. steric hindrance between the NH2 group and the benzene ring, as indicated by the N—C(ortho) contacts in the range 2.859 (2)–2.893 (2) Å, and prevents conjugation between the N—C—N system and the benzene ring. Indeed, the C—C(amidine) distances are in the range 1.479 (3)–1.481 (3) Å and compare well with the expected Csp2—Csp2 single-bond length of 1.482 (1) Å (Allen et al., 1987). Interestingly, only the nonplanar conformation has been observed in small-molecule crystal structures, whereas in structures containing benzamidinium in the Protein Data Bank (PDB; Berman et al., 2000) the most frequently encountered one is the planar conformation (Li et al., 2009). The C—N bond lengths are in the range 1.305 (2)–1.317 (2) Å, evidencing the delocalization of the π electrons and double-bond character compared with the corresponding bond lengths found in benzamidine [1.294 (3) and 1.344 (3) Å; Barker et al., 1996] and benzdiamidine [1.283 (2) and 1.349 (2) Å; Jokić et al., 2001].
The benzene rings in the Dmb- anions of polymorphs (I) and (II) are essentially planar, and the methoxy substituents force the carboxylate groups to be almost orthogonal to the plane of the aromatic fragment [the twist angle between the aromatic ring and the carboxylate group is 78.9 (1)° for polymorph (I), and 88.7 (1) and 72.3 (1)° for polymorph (II)]. In these anions, the bond lengths and angles of the benzene ring are in accord with the corresponding values obtained for both the orthorhombic and tetragonal forms of 2,6-dimethoxybenzoic acid (Portalone, 2009, 2011b) and for 4-methoxybenzamidinium 2,6-dimethoxybenzoate (Portalone, 2012). The C—O distances of the carboxylate group range from 1.246 (2) to 1.255 (2) Å, indicating the delocalization of the negative charge.
The molecular components of both polymorphs are joined by two N+—H···O- (±)CAHB hydrogen bonds to form ionic dimers with graph-set motif R22(8). Remarkably, at variance with the well known carboxylic dimer R22(8) motif, in both polymorphs the carboxylate–amidinium pairs are not planar, as the dihedral angles for the planes defined by the CN2+ and CO2- atoms are in the range 26.8–29.5°. Nonetheless, the interface is very stable, as indicated by the N+—H···O- parameters: N+···O- distances in the range 2.785 (2)–2.868 (2) Å) and N+—H···O- angles in the range 148 (2)–177 (2)°. This deviation from planarity of carboxylate–amidinium pairs has previously been observed in the crystal structure of 3-amidinium benzoate (Papoutsakis et al., 1999).
Due to the protonated base, supramolecular aggregations in (I) and (II) are dominated by an extensive series of N+—H···O- (±)CAHB hydrogen bonds (Tables 1 and 2). In the supramolecular structures of polymorphs (I) and (II) (Figs. 3 and 4), eight and four hydrogen bonds, respectively, link the molecular components into a one-dimensional structure. As previously mentioned, each subunit, built from the ion pairs of the asymmetric unit, forms R22(8) dimers via the bidentate interaction of the N—H and C═O groups. These subunits are then joined into linear chains through hydrogen bonding to adjacent antiparallel dimers. Such disposition of dimers and catemers has frequently been observed in the solid-state structures of amides (Meléndez & Hamilton, 1998).
From a supramolecular retrosynthesis perspective, only those synthons that occurr repeatedly in crystal structures, namely, robust synthons of a particular set of functional groups, are useful in crystal design (Nangia & Desiraju, 1998). Moreover, hydrogen bonds are often formed in a hierarchical fashion (Etter, 1990; Allen et al., 1999; Bis et al., 2007; Shattock et al., 2008) and there is a need to ascertain the prevalence of a particular heterosynthon over another in a competitive environment. From the results reported herein, the crystal structures of polymorphs (I) and (II) are both consistent with the R22(8) supramolecular heterosynthon persistence exhibited by the benzamidinium adducts that have been archived in the Cambridge Structural Database (CSD, Version?; Allen, 2002). Consequently, the existence of polymorphism in these molecular salts should be related to the conformational flexibility of the carboxylate and amidinium groups. Polymorphs (I) and (II) therefore represent examples of conformational polymorphism. To the best of our knowledge, the only exception to the complementarity of amidinium and carboxylate groups has been reported for benzamidinium isoorotate (Portalone, 2010).