The crystal structure of the proton-transfer compound of 1,1′-biphenyl-4,4′-diamine (benzidine) with 3,5-dinitrosalicylic acid, viz. 1,1′-biphenyl-4,4′-diaminium bis(4′-amino-1,1′-biphenyl-4-aminium) tetrakis(2-carboxy-4,6-dinitrophenolate) ethanol disolvate, C12H14N22+·2C12H13N2+·4C7H3N2O7−·2C2H6O, shows the presence of both diprotonated and monoprotonated benzidine cations. The diprotonated species lie across crystallographic inversion centres in the unit cell, while the monoprotonated species occupy general sites. All amine H atoms participate in hydrogen bonding with carboxyl, phenolate and nitro O-atom acceptors of the salicylate anions, which also participate in hydrogen bonding with the disordered ethanol solvent molecules. Significant inter-ring anion–anion and anion–monocation π–π interactions are also present, giving a three-dimensional framework structure.
Supporting information
CCDC reference: 616274
The title compound was synthesized by heating 1 mmol quantities of DNSA and benzidine in 80% ethanol/water (50 ml) for 10 min under reflux. After concentration to ca 30 ml, partial room-temperature evaporation of the hot-filtered solution gave yellow–brown prismatic crystals of (I) (m.p. 480–483 K).
H atoms potentially involved in hydrogen-bonding interactions were located by difference methods and their positional and isotropic displacement parameters were refined. Other H atoms were included in the refinement in calculated positions [C—H = 0.93–0.99 Å], using the riding-model approximation, with Uiso(H) fixed at 1.2Ueq(C).
Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL (Bruker, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON.
1,1'-biphenyl-4,4'-diaminium bis(4'-amino-1,1'-biphenyl-4-aminium) tetrakis(2-carboxy-4,6-dinitrophenolate) ethanol disolvate
top
Crystal data top
C12H14N22+·2C12H13N2+·4C7H3N2O7−·2C2H6O | F(000) = 1620 |
Mr = 1557.34 | Dx = 1.447 Mg m−3 |
Monoclinic, P21/c | Melting point: 479.7–482.9 (dec) K |
Hall symbol: -P 2ybc | Mo Kα radiation, λ = 0.71073 Å |
a = 18.862 (2) Å | Cell parameters from 1773 reflections |
b = 10.5138 (11) Å | θ = 2.3–19.1° |
c = 19.081 (2) Å | µ = 0.12 mm−1 |
β = 109.154 (2)° | T = 295 K |
V = 3574.6 (7) Å3 | Prism, yellow–brown |
Z = 2 | 0.45 × 0.15 × 0.08 mm |
Data collection top
Bruker SMART CCD diffractometer | 3072 reflections with I > 2σ(I) |
Radiation source: sealed tube | Rint = 0.063 |
Graphite monochromator | θmax = 27.6°, θmin = 2.2° |
ϕ and ω scans | h = −24→16 |
22178 measured reflections | k = −11→13 |
8165 independent reflections | l = −24→24 |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.098 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.87 | w = 1/[σ2(Fo2) + (0.0239P)2] where P = (Fo2 + 2Fc2)/3 |
8165 reflections | (Δ/σ)max = 0.002 |
549 parameters | Δρmax = 0.19 e Å−3 |
0 restraints | Δρmin = −0.15 e Å−3 |
Crystal data top
C12H14N22+·2C12H13N2+·4C7H3N2O7−·2C2H6O | V = 3574.6 (7) Å3 |
Mr = 1557.34 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 18.862 (2) Å | µ = 0.12 mm−1 |
b = 10.5138 (11) Å | T = 295 K |
c = 19.081 (2) Å | 0.45 × 0.15 × 0.08 mm |
β = 109.154 (2)° | |
Data collection top
Bruker SMART CCD diffractometer | 3072 reflections with I > 2σ(I) |
22178 measured reflections | Rint = 0.063 |
8165 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.098 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.87 | Δρmax = 0.19 e Å−3 |
8165 reflections | Δρmin = −0.15 e Å−3 |
549 parameters | |
Special details top
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'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 | Uiso*/Ueq | Occ. (<1) |
N4D | 0.43574 (15) | 0.1927 (2) | 0.16941 (13) | 0.0429 (9) | |
C1D | 0.48955 (14) | 0.4535 (2) | 0.02470 (12) | 0.0369 (9) | |
C2D | 0.51012 (13) | 0.3270 (2) | 0.02723 (12) | 0.0431 (10) | |
C3D | 0.49182 (14) | 0.2413 (2) | 0.07314 (13) | 0.0455 (10) | |
C4D | 0.45242 (13) | 0.2816 (2) | 0.11734 (13) | 0.0374 (9) | |
C5D | 0.43044 (15) | 0.4054 (2) | 0.11621 (14) | 0.0558 (11) | |
C6D | 0.44887 (15) | 0.4898 (2) | 0.06944 (14) | 0.0602 (11) | |
N4C | 0.10555 (16) | 0.9872 (3) | 0.49959 (14) | 0.0598 (11) | |
N41C | 0.37076 (18) | 0.9499 (2) | 0.12627 (17) | 0.0549 (11) | |
C1C | 0.21828 (15) | 0.9816 (2) | 0.33928 (14) | 0.0406 (9) | |
C2C | 0.14193 (16) | 0.9628 (3) | 0.32006 (14) | 0.0620 (11) | |
C3C | 0.10484 (16) | 0.9647 (3) | 0.37120 (15) | 0.0686 (13) | |
C4C | 0.14459 (16) | 0.9866 (2) | 0.44408 (15) | 0.0497 (11) | |
C5C | 0.21944 (17) | 1.0045 (2) | 0.46612 (14) | 0.0607 (11) | |
C6C | 0.25613 (15) | 1.0023 (2) | 0.41433 (14) | 0.0598 (11) | |
C11C | 0.25797 (15) | 0.9758 (2) | 0.28410 (13) | 0.0405 (9) | |
C21C | 0.33445 (15) | 0.9617 (2) | 0.30435 (14) | 0.0518 (11) | |
C31C | 0.37132 (15) | 0.9513 (2) | 0.25312 (14) | 0.0502 (10) | |
C41C | 0.33200 (16) | 0.9548 (2) | 0.17830 (14) | 0.0421 (10) | |
C51C | 0.25602 (16) | 0.9707 (2) | 0.15665 (14) | 0.0554 (11) | |
C61C | 0.21961 (15) | 0.9815 (2) | 0.20846 (14) | 0.0531 (11) | |
O2A | 0.19965 (10) | 0.64259 (16) | 0.12008 (10) | 0.0568 (7) | |
O31A | 0.05855 (11) | 0.5914 (2) | 0.12155 (11) | 0.0813 (9) | |
O32A | 0.03550 (13) | 0.6965 (3) | 0.20652 (14) | 0.1420 (13) | |
O51A | 0.21813 (15) | 0.6419 (2) | 0.45221 (12) | 0.1118 (11) | |
O52A | 0.33430 (15) | 0.6507 (2) | 0.46371 (11) | 0.1010 (11) | |
O71A | 0.41757 (11) | 0.62515 (18) | 0.24999 (11) | 0.0737 (8) | |
O72A | 0.33586 (13) | 0.64814 (18) | 0.13806 (13) | 0.0607 (8) | |
N3A | 0.07911 (15) | 0.6437 (3) | 0.18152 (15) | 0.0747 (11) | |
N5A | 0.2681 (2) | 0.6474 (2) | 0.42585 (14) | 0.0732 (13) | |
C1A | 0.28934 (15) | 0.6402 (2) | 0.23949 (14) | 0.0435 (10) | |
C2A | 0.21433 (15) | 0.6406 (2) | 0.19032 (15) | 0.0449 (10) | |
C3A | 0.15841 (15) | 0.6422 (2) | 0.22624 (15) | 0.0490 (10) | |
C4A | 0.17515 (16) | 0.6464 (2) | 0.30195 (15) | 0.0549 (11) | |
C5A | 0.24900 (18) | 0.6458 (2) | 0.34559 (14) | 0.0509 (10) | |
C6A | 0.30597 (15) | 0.6427 (2) | 0.31512 (14) | 0.0496 (11) | |
C7A | 0.35296 (18) | 0.6370 (2) | 0.21045 (18) | 0.0516 (11) | |
O2B | 0.32386 (10) | 0.31570 (15) | 0.21442 (9) | 0.0537 (7) | |
O31B | 0.46337 (11) | 0.2989 (2) | 0.31660 (12) | 0.0854 (10) | |
O32B | 0.47081 (11) | 0.41536 (17) | 0.41125 (11) | 0.0698 (8) | |
O51B | 0.28318 (12) | 0.3210 (2) | 0.52540 (11) | 0.0820 (9) | |
O52B | 0.16754 (13) | 0.3205 (2) | 0.45598 (11) | 0.0973 (10) | |
O71B | 0.10119 (11) | 0.3095 (2) | 0.18682 (10) | 0.0835 (9) | |
O72B | 0.18955 (13) | 0.31358 (19) | 0.13545 (10) | 0.0701 (9) | |
N3B | 0.43459 (14) | 0.3500 (2) | 0.35821 (13) | 0.0566 (10) | |
N5B | 0.23424 (17) | 0.3226 (2) | 0.46471 (14) | 0.0654 (11) | |
C1B | 0.22656 (15) | 0.3139 (2) | 0.26719 (14) | 0.0430 (10) | |
C2B | 0.30369 (15) | 0.3182 (2) | 0.27207 (14) | 0.0436 (10) | |
C3B | 0.35465 (15) | 0.3321 (2) | 0.34556 (14) | 0.0445 (12) | |
C4B | 0.33251 (16) | 0.3351 (2) | 0.40770 (14) | 0.0517 (10) | |
C5B | 0.25779 (16) | 0.3243 (2) | 0.39910 (14) | 0.0468 (10) | |
C6B | 0.20481 (15) | 0.3158 (2) | 0.32950 (15) | 0.0501 (11) | |
C7B | 0.16737 (18) | 0.3113 (3) | 0.19375 (16) | 0.0546 (11) | |
O1E | 1.01662 (12) | 0.3206 (2) | 0.04173 (12) | 0.0744 (9) | |
C1E | 1.0060 (3) | 0.1916 (4) | 0.0164 (3) | 0.144 (3) | |
C2E | 0.9594 (6) | 0.1286 (6) | 0.0536 (9) | 0.246 (8) | 0.806 (13) |
C21E | 0.9356 (12) | 0.1340 (19) | −0.0278 (18) | 0.149 (11) | 0.194 (13) |
H2D | 0.537000 | 0.298900 | −0.002800 | 0.0520* | |
H3D | 0.506200 | 0.156600 | 0.074000 | 0.0550* | |
H5D | 0.403500 | 0.432600 | 0.146400 | 0.0670* | |
H6D | 0.433300 | 0.573900 | 0.068100 | 0.0720* | |
H41D | 0.4132 (13) | 0.125 (2) | 0.1462 (12) | 0.047 (9)* | |
H42D | 0.3982 (17) | 0.234 (2) | 0.1845 (15) | 0.106 (11)* | |
H43D | 0.4864 (18) | 0.169 (2) | 0.1972 (16) | 0.118 (12)* | |
H2C | 0.114400 | 0.948200 | 0.270500 | 0.0750* | |
H3C | 0.053300 | 0.951300 | 0.356300 | 0.0820* | |
H5C | 0.246200 | 1.018200 | 0.516000 | 0.0730* | |
H6C | 0.307800 | 1.015100 | 0.430100 | 0.0720* | |
H21C | 0.362400 | 0.959000 | 0.354600 | 0.0620* | |
H31C | 0.423200 | 0.942000 | 0.269200 | 0.0600* | |
H41C | 0.0900 (17) | 1.065 (3) | 0.5050 (16) | 0.097 (14)* | |
H42C | 0.138 (2) | 0.943 (3) | 0.541 (2) | 0.192 (16)* | |
H43C | 0.0659 (15) | 0.928 (2) | 0.4857 (13) | 0.061 (10)* | |
H44C | 0.3401 (17) | 0.926 (3) | 0.0798 (17) | 0.114 (14)* | |
H45C | 0.4122 (16) | 0.907 (3) | 0.1402 (16) | 0.094 (14)* | |
H51C | 0.228400 | 0.974300 | 0.106400 | 0.0660* | |
H61C | 0.167900 | 0.993100 | 0.192200 | 0.0640* | |
H4A | 0.137200 | 0.649500 | 0.323000 | 0.0660* | |
H6A | 0.355800 | 0.642300 | 0.345900 | 0.0600* | |
H72A | 0.2861 (16) | 0.647 (3) | 0.1215 (15) | 0.084 (12)* | |
H4B | 0.367800 | 0.344400 | 0.454700 | 0.0620* | |
H6B | 0.154100 | 0.311300 | 0.324500 | 0.0600* | |
H72B | 0.2409 (17) | 0.314 (2) | 0.1548 (16) | 0.094 (11)* | |
H1E | 1.0476 (17) | 0.315 (3) | 0.0904 (17) | 0.106 (13)* | |
H3E | 0.958600 | 0.038700 | 0.044400 | 0.296* | 0.806 |
H4E | 0.909200 | 0.161600 | 0.034900 | 0.296* | 0.806 |
H2E | 0.979600 | 0.143900 | 0.106000 | 0.296* | 0.806 |
H5E | 0.930400 | 0.140300 | −0.079500 | 0.180* | 0.194 |
H6E | 0.894700 | 0.177500 | −0.018800 | 0.180* | 0.194 |
H7E | 0.935200 | 0.046000 | −0.014400 | 0.180* | 0.194 |
H11E | 0.98200 | 0.190000 | −0.03600 | 0.170* | |
H12E | 1.05300 | 0.150000 | 0.02800 | 0.170* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N4D | 0.0479 (17) | 0.0407 (15) | 0.0429 (14) | −0.0037 (14) | 0.0185 (13) | 0.0036 (12) |
C1D | 0.0386 (16) | 0.0345 (15) | 0.0401 (16) | 0.0010 (13) | 0.0164 (13) | 0.0017 (12) |
C2D | 0.0507 (18) | 0.0438 (16) | 0.0424 (16) | −0.0011 (14) | 0.0257 (14) | −0.0039 (13) |
C3D | 0.0579 (19) | 0.0367 (15) | 0.0443 (16) | 0.0037 (14) | 0.0201 (15) | 0.0035 (13) |
C4D | 0.0361 (16) | 0.0414 (16) | 0.0332 (15) | −0.0038 (13) | 0.0093 (13) | 0.0032 (12) |
C5D | 0.071 (2) | 0.0463 (17) | 0.070 (2) | 0.0127 (16) | 0.0501 (18) | 0.0107 (15) |
C6D | 0.081 (2) | 0.0393 (17) | 0.081 (2) | 0.0166 (16) | 0.0547 (19) | 0.0164 (15) |
N4C | 0.0563 (19) | 0.079 (2) | 0.0497 (17) | 0.0005 (19) | 0.0251 (15) | 0.0004 (16) |
N41C | 0.061 (2) | 0.0577 (17) | 0.0569 (19) | −0.0035 (17) | 0.0341 (16) | −0.0013 (15) |
C1C | 0.0441 (17) | 0.0402 (15) | 0.0394 (16) | 0.0011 (14) | 0.0161 (14) | 0.0037 (12) |
C2C | 0.051 (2) | 0.100 (2) | 0.0339 (16) | 0.0123 (19) | 0.0124 (16) | 0.0000 (16) |
C3C | 0.0442 (19) | 0.115 (3) | 0.0471 (19) | 0.0146 (18) | 0.0158 (17) | 0.0069 (18) |
C4C | 0.053 (2) | 0.0585 (18) | 0.0437 (18) | 0.0085 (16) | 0.0243 (16) | 0.0055 (14) |
C5C | 0.060 (2) | 0.086 (2) | 0.0377 (17) | −0.0112 (19) | 0.0184 (16) | −0.0024 (15) |
C6C | 0.0485 (19) | 0.084 (2) | 0.0488 (19) | −0.0149 (16) | 0.0187 (16) | −0.0010 (16) |
C11C | 0.0448 (17) | 0.0386 (15) | 0.0387 (16) | 0.0036 (14) | 0.0145 (14) | 0.0050 (12) |
C21C | 0.052 (2) | 0.0630 (19) | 0.0385 (16) | 0.0090 (16) | 0.0122 (15) | 0.0058 (14) |
C31C | 0.0439 (18) | 0.0593 (18) | 0.0504 (18) | 0.0081 (14) | 0.0196 (16) | 0.0098 (15) |
C41C | 0.0538 (19) | 0.0335 (15) | 0.0455 (17) | −0.0051 (14) | 0.0250 (16) | −0.0001 (13) |
C51C | 0.052 (2) | 0.077 (2) | 0.0385 (16) | −0.0123 (17) | 0.0166 (16) | 0.0017 (15) |
C61C | 0.0418 (18) | 0.073 (2) | 0.0463 (18) | 0.0000 (15) | 0.0171 (15) | 0.0066 (15) |
O2A | 0.0540 (13) | 0.0783 (13) | 0.0401 (11) | −0.0069 (11) | 0.0181 (10) | −0.0070 (10) |
O31A | 0.0558 (14) | 0.1349 (19) | 0.0545 (14) | −0.0151 (13) | 0.0197 (12) | −0.0188 (13) |
O32A | 0.0570 (16) | 0.238 (3) | 0.131 (2) | 0.0069 (19) | 0.0310 (16) | −0.087 (2) |
O51A | 0.128 (2) | 0.162 (2) | 0.0612 (16) | −0.0241 (19) | 0.0526 (16) | −0.0012 (14) |
O52A | 0.101 (2) | 0.136 (2) | 0.0519 (15) | −0.0118 (18) | 0.0058 (14) | 0.0054 (14) |
O71A | 0.0436 (13) | 0.0902 (15) | 0.0834 (16) | −0.0006 (12) | 0.0155 (12) | −0.0240 (12) |
O72A | 0.0537 (15) | 0.0681 (14) | 0.0687 (15) | −0.0027 (13) | 0.0317 (13) | −0.0060 (11) |
N3A | 0.0533 (19) | 0.106 (2) | 0.072 (2) | −0.0087 (17) | 0.0304 (17) | −0.0237 (17) |
N5A | 0.098 (3) | 0.0713 (18) | 0.0501 (19) | −0.009 (2) | 0.0242 (19) | 0.0021 (15) |
C1A | 0.0471 (19) | 0.0390 (16) | 0.0443 (17) | −0.0009 (14) | 0.0148 (15) | −0.0053 (13) |
C2A | 0.0488 (19) | 0.0424 (16) | 0.0451 (18) | −0.0038 (14) | 0.0177 (16) | −0.0040 (14) |
C3A | 0.0419 (18) | 0.0584 (18) | 0.0476 (18) | −0.0056 (15) | 0.0159 (15) | −0.0060 (14) |
C4A | 0.064 (2) | 0.0582 (19) | 0.0520 (19) | −0.0116 (17) | 0.0320 (17) | −0.0039 (15) |
C5A | 0.065 (2) | 0.0490 (17) | 0.0375 (17) | −0.0043 (17) | 0.0151 (17) | −0.0006 (14) |
C6A | 0.051 (2) | 0.0400 (16) | 0.0511 (19) | −0.0013 (14) | 0.0075 (16) | 0.0004 (14) |
C7A | 0.052 (2) | 0.0439 (17) | 0.058 (2) | −0.0024 (16) | 0.0169 (18) | −0.0139 (16) |
O2B | 0.0551 (13) | 0.0680 (12) | 0.0443 (11) | 0.0039 (10) | 0.0247 (11) | 0.0039 (10) |
O31B | 0.0567 (14) | 0.1201 (19) | 0.0827 (16) | 0.0006 (13) | 0.0275 (13) | −0.0318 (14) |
O32B | 0.0694 (15) | 0.0759 (14) | 0.0603 (13) | −0.0220 (12) | 0.0163 (11) | −0.0080 (11) |
O51B | 0.0876 (18) | 0.1149 (17) | 0.0446 (13) | −0.0044 (14) | 0.0233 (13) | −0.0028 (13) |
O52B | 0.0708 (16) | 0.158 (2) | 0.0768 (16) | 0.0065 (18) | 0.0428 (15) | 0.0089 (14) |
O71B | 0.0468 (14) | 0.142 (2) | 0.0579 (14) | 0.0004 (14) | 0.0119 (12) | 0.0100 (13) |
O72B | 0.0578 (15) | 0.1067 (17) | 0.0455 (13) | 0.0117 (14) | 0.0166 (12) | 0.0081 (11) |
N3B | 0.0587 (19) | 0.0587 (17) | 0.0517 (16) | −0.0043 (15) | 0.0170 (15) | −0.0003 (13) |
N5B | 0.075 (2) | 0.0756 (18) | 0.0532 (18) | 0.0017 (18) | 0.0313 (18) | 0.0016 (15) |
C1B | 0.0466 (18) | 0.0446 (16) | 0.0412 (16) | 0.0041 (14) | 0.0190 (15) | 0.0062 (13) |
C2B | 0.0527 (19) | 0.0386 (16) | 0.0422 (17) | 0.0036 (15) | 0.0194 (16) | 0.0061 (13) |
C3B | 0.0413 (18) | 0.0427 (16) | 0.0503 (18) | −0.0003 (14) | 0.0161 (15) | 0.0034 (14) |
C4B | 0.060 (2) | 0.0477 (17) | 0.0450 (17) | 0.0014 (16) | 0.0139 (16) | 0.0031 (14) |
C5B | 0.0527 (19) | 0.0506 (17) | 0.0397 (17) | −0.0002 (16) | 0.0186 (16) | 0.0011 (14) |
C6B | 0.0484 (19) | 0.0472 (17) | 0.0596 (19) | 0.0046 (14) | 0.0245 (17) | 0.0058 (15) |
C7B | 0.053 (2) | 0.066 (2) | 0.0477 (19) | 0.0038 (18) | 0.0205 (18) | 0.0082 (16) |
O1E | 0.0632 (15) | 0.0954 (18) | 0.0551 (15) | 0.0043 (14) | 0.0063 (12) | 0.0036 (14) |
C1E | 0.160 (5) | 0.098 (4) | 0.173 (5) | −0.034 (3) | 0.053 (4) | −0.030 (3) |
C2E | 0.210 (10) | 0.148 (6) | 0.46 (2) | −0.106 (6) | 0.218 (15) | −0.143 (9) |
C21E | 0.14 (2) | 0.123 (19) | 0.11 (2) | 0.008 (17) | −0.061 (17) | −0.056 (15) |
Geometric parameters (Å, º) top
O2A—C2A | 1.277 (3) | C2C—C3C | 1.375 (4) |
O31A—N3A | 1.213 (3) | C3C—C4C | 1.366 (4) |
O32A—N3A | 1.212 (4) | C4C—C5C | 1.348 (4) |
O51A—N5A | 1.207 (5) | C5C—C6C | 1.380 (4) |
O52A—N5A | 1.221 (4) | C11C—C21C | 1.374 (4) |
O71A—C7A | 1.211 (4) | C11C—C61C | 1.387 (3) |
O72A—C7A | 1.317 (4) | C21C—C31C | 1.377 (4) |
O72A—H72A | 0.89 (3) | C31C—C41C | 1.377 (4) |
O2B—C2B | 1.277 (3) | C41C—C51C | 1.365 (4) |
O31B—N3B | 1.223 (3) | C51C—C61C | 1.381 (4) |
O32B—N3B | 1.229 (3) | C2C—H2C | 0.9300 |
O51B—N5B | 1.222 (3) | C3C—H3C | 0.9300 |
O52B—N5B | 1.214 (4) | C5C—H5C | 0.9300 |
O71B—C7B | 1.212 (4) | C6C—H6C | 0.9300 |
O72B—C7B | 1.311 (4) | C21C—H21C | 0.9300 |
O72B—H72B | 0.92 (3) | C31C—H31C | 0.9300 |
O1E—C1E | 1.432 (5) | C51C—H51C | 0.9300 |
O1E—H1E | 0.92 (3) | C61C—H61C | 0.9300 |
N4D—C4D | 1.471 (3) | C1A—C6A | 1.373 (4) |
N4D—H41D | 0.87 (2) | C1A—C2A | 1.418 (4) |
N4D—H43D | 0.96 (3) | C1A—C7A | 1.478 (5) |
N4D—H42D | 0.95 (3) | C2A—C3A | 1.434 (4) |
N4C—C4C | 1.475 (4) | C3A—C4A | 1.375 (4) |
N41C—C41C | 1.414 (4) | C4A—C5A | 1.368 (4) |
N4C—H43C | 0.94 (3) | C5A—C6A | 1.380 (4) |
N4C—H41C | 0.89 (3) | C4A—H4A | 0.9300 |
N4C—H42C | 0.95 (4) | C6A—H6A | 0.9300 |
N41C—H45C | 0.87 (3) | C1B—C6B | 1.379 (4) |
N41C—H44C | 0.92 (3) | C1B—C7B | 1.478 (4) |
N3A—C3A | 1.459 (4) | C1B—C2B | 1.428 (4) |
N5A—C5A | 1.454 (4) | C2B—C3B | 1.424 (4) |
N3B—C3B | 1.459 (4) | C3B—C4B | 1.381 (4) |
N5B—C5B | 1.459 (4) | C4B—C5B | 1.369 (4) |
C1D—C6D | 1.376 (4) | C5B—C6B | 1.378 (4) |
C1D—C1Di | 1.498 (3) | C4B—H4B | 0.9300 |
C1D—C2D | 1.382 (3) | C6B—H6B | 0.9300 |
C2D—C3D | 1.377 (3) | C1E—C2E | 1.458 (14) |
C3D—C4D | 1.362 (4) | C1E—C21E | 1.45 (3) |
C4D—C5D | 1.364 (3) | C1E—H11E | 0.9500 |
C5D—C6D | 1.381 (3) | C1E—H12E | 0.9500 |
C2D—H2D | 0.9300 | C2E—H2E | 0.9600 |
C3D—H3D | 0.9300 | C2E—H3E | 0.9600 |
C5D—H5D | 0.9300 | C2E—H4E | 0.9600 |
C6D—H6D | 0.9300 | C21E—H5E | 0.9600 |
C1C—C6C | 1.392 (4) | C21E—H6E | 0.9600 |
C1C—C2C | 1.379 (4) | C21E—H7E | 0.9600 |
C1C—C11C | 1.480 (4) | | |
| | | |
C7A—O72A—H72A | 103.8 (18) | C4C—C5C—H5C | 120.00 |
C7B—O72B—H72B | 104.3 (18) | C6C—C5C—H5C | 120.00 |
C1E—O1E—H1E | 105 (2) | C1C—C6C—H6C | 119.00 |
C4D—N4D—H43D | 98.2 (17) | C5C—C6C—H6C | 119.00 |
C4D—N4D—H41D | 110.6 (15) | C11C—C21C—H21C | 119.00 |
H41D—N4D—H43D | 107 (2) | C31C—C21C—H21C | 119.00 |
H41D—N4D—H42D | 104 (2) | C41C—C31C—H31C | 120.00 |
H42D—N4D—H43D | 131 (2) | C21C—C31C—H31C | 120.00 |
C4D—N4D—H42D | 105.0 (14) | C61C—C51C—H51C | 120.00 |
H41C—N4C—H43C | 112 (3) | C41C—C51C—H51C | 120.00 |
H42C—N4C—H43C | 98 (3) | C11C—C61C—H61C | 119.00 |
C4C—N4C—H41C | 111 (2) | C51C—C61C—H61C | 119.00 |
C4C—N4C—H43C | 109.4 (16) | C2A—C1A—C7A | 120.6 (2) |
C4C—N4C—H42C | 105 (2) | C6A—C1A—C7A | 117.5 (3) |
H41C—N4C—H42C | 120 (3) | C2A—C1A—C6A | 122.0 (3) |
C41C—N41C—H44C | 112 (2) | C1A—C2A—C3A | 114.5 (2) |
H44C—N41C—H45C | 112 (3) | O2A—C2A—C3A | 124.2 (3) |
C41C—N41C—H45C | 115 (2) | O2A—C2A—C1A | 121.4 (3) |
O31A—N3A—C3A | 119.7 (3) | C2A—C3A—C4A | 123.5 (3) |
O31A—N3A—O32A | 122.1 (3) | N3A—C3A—C4A | 116.9 (3) |
O32A—N3A—C3A | 118.2 (3) | N3A—C3A—C2A | 119.6 (2) |
O51A—N5A—C5A | 118.8 (3) | C3A—C4A—C5A | 118.5 (3) |
O51A—N5A—O52A | 122.8 (3) | C4A—C5A—C6A | 121.5 (2) |
O52A—N5A—C5A | 118.4 (3) | N5A—C5A—C6A | 119.1 (3) |
O31B—N3B—C3B | 119.4 (2) | N5A—C5A—C4A | 119.5 (3) |
O31B—N3B—O32B | 122.4 (3) | C1A—C6A—C5A | 120.2 (3) |
O32B—N3B—C3B | 118.3 (2) | O71A—C7A—C1A | 122.9 (3) |
O52B—N5B—C5B | 118.4 (2) | O72A—C7A—C1A | 116.2 (3) |
O51B—N5B—C5B | 117.7 (3) | O71A—C7A—O72A | 120.9 (3) |
O51B—N5B—O52B | 123.8 (3) | C3A—C4A—H4A | 121.00 |
C1Di—C1D—C6D | 121.7 (2) | C5A—C4A—H4A | 121.00 |
C1Di—C1D—C2D | 121.4 (2) | C5A—C6A—H6A | 120.00 |
C2D—C1D—C6D | 116.9 (2) | C1A—C6A—H6A | 120.00 |
C1D—C2D—C3D | 121.7 (2) | C2B—C1B—C7B | 119.9 (2) |
C2D—C3D—C4D | 119.5 (2) | C2B—C1B—C6B | 121.9 (2) |
N4D—C4D—C5D | 119.1 (2) | C6B—C1B—C7B | 118.2 (3) |
N4D—C4D—C3D | 120.1 (2) | O2B—C2B—C3B | 123.7 (3) |
C3D—C4D—C5D | 120.8 (2) | C1B—C2B—C3B | 114.3 (2) |
C4D—C5D—C6D | 118.9 (2) | O2B—C2B—C1B | 121.9 (2) |
C1D—C6D—C5D | 122.2 (2) | C2B—C3B—C4B | 123.5 (3) |
C1D—C2D—H2D | 119.00 | N3B—C3B—C2B | 120.2 (2) |
C3D—C2D—H2D | 119.00 | N3B—C3B—C4B | 116.3 (2) |
C4D—C3D—H3D | 120.00 | C3B—C4B—C5B | 119.0 (2) |
C2D—C3D—H3D | 120.00 | C4B—C5B—C6B | 120.9 (3) |
C6D—C5D—H5D | 120.00 | N5B—C5B—C6B | 119.8 (3) |
C4D—C5D—H5D | 121.00 | N5B—C5B—C4B | 119.3 (2) |
C5D—C6D—H6D | 119.00 | C1B—C6B—C5B | 120.3 (3) |
C1D—C6D—H6D | 119.00 | O72B—C7B—C1B | 116.9 (3) |
C6C—C1C—C11C | 122.0 (3) | O71B—C7B—O72B | 120.8 (3) |
C2C—C1C—C6C | 115.8 (3) | O71B—C7B—C1B | 122.3 (3) |
C2C—C1C—C11C | 122.2 (2) | C5B—C4B—H4B | 120.00 |
C1C—C2C—C3C | 122.7 (2) | C3B—C4B—H4B | 121.00 |
C2C—C3C—C4C | 119.2 (3) | C1B—C6B—H6B | 120.00 |
C3C—C4C—C5C | 120.7 (3) | C5B—C6B—H6B | 120.00 |
N4C—C4C—C5C | 119.6 (2) | O1E—C1E—C2E | 107.8 (5) |
N4C—C4C—C3C | 119.7 (3) | O1E—C1E—C21E | 126.3 (9) |
C4C—C5C—C6C | 119.6 (2) | O1E—C1E—H11E | 109.9 |
C1C—C6C—C5C | 122.1 (3) | O1E—C1E—H12E | 109.9 |
C21C—C11C—C61C | 116.0 (2) | C2E—C1E—H11E | 109.9 |
C1C—C11C—C21C | 122.3 (2) | C2E—C1E—H12E | 109.9 |
C1C—C11C—C61C | 121.7 (3) | H11E—C1E—H12E | 109.5 |
C11C—C21C—C31C | 122.5 (2) | C1E—C2E—H3E | 110.00 |
C21C—C31C—C41C | 120.6 (3) | C1E—C2E—H4E | 109.00 |
N41C—C41C—C51C | 121.7 (3) | H2E—C2E—H3E | 109.00 |
C31C—C41C—C51C | 118.2 (3) | H2E—C2E—H4E | 109.00 |
N41C—C41C—C31C | 120.0 (3) | H3E—C2E—H4E | 109.00 |
C41C—C51C—C61C | 120.8 (2) | C1E—C21E—H5E | 109.00 |
C11C—C61C—C51C | 121.9 (3) | C1E—C21E—H6E | 109.00 |
C3C—C2C—H2C | 119.00 | C1E—C21E—H7E | 109.00 |
C1C—C2C—H2C | 119.00 | H5E—C21E—H6E | 109.00 |
C4C—C3C—H3C | 120.00 | H5E—C21E—H7E | 109.00 |
C2C—C3C—H3C | 120.00 | H6E—C21E—H7E | 110.00 |
| | | |
O32A—N3A—C3A—C4A | 28.5 (4) | C21C—C11C—C61C—C51C | 1.4 (3) |
O31A—N3A—C3A—C4A | −150.5 (3) | C11C—C21C—C31C—C41C | 0.0 (3) |
O31A—N3A—C3A—C2A | 31.5 (4) | C21C—C31C—C41C—N41C | 177.1 (2) |
O32A—N3A—C3A—C2A | −149.5 (3) | C21C—C31C—C41C—C51C | 1.0 (3) |
O52A—N5A—C5A—C4A | −177.8 (2) | C31C—C41C—C51C—C61C | −0.7 (3) |
O52A—N5A—C5A—C6A | 2.7 (3) | N41C—C41C—C51C—C61C | −176.8 (2) |
O51A—N5A—C5A—C6A | −175.3 (2) | C41C—C51C—C61C—C11C | −0.5 (3) |
O51A—N5A—C5A—C4A | 4.2 (3) | C6A—C1A—C7A—O72A | −173.1 (2) |
O32B—N3B—C3B—C2B | 147.7 (2) | C6A—C1A—C2A—C3A | −0.7 (3) |
O31B—N3B—C3B—C2B | −33.0 (3) | C6A—C1A—C7A—O71A | 6.8 (3) |
O32B—N3B—C3B—C4B | −29.6 (3) | C6A—C1A—C2A—O2A | 177.6 (2) |
O31B—N3B—C3B—C4B | 149.6 (2) | C7A—C1A—C2A—O2A | −2.4 (3) |
O51B—N5B—C5B—C6B | 174.8 (2) | C2A—C1A—C7A—O72A | 6.9 (3) |
O51B—N5B—C5B—C4B | −5.6 (3) | C2A—C1A—C7A—O71A | −173.2 (2) |
O52B—N5B—C5B—C6B | −3.9 (3) | C7A—C1A—C6A—C5A | 180.0 (2) |
O52B—N5B—C5B—C4B | 175.7 (2) | C2A—C1A—C6A—C5A | 0.0 (3) |
C6D—C1D—C1Di—C6Di | 180.0 (3) | C7A—C1A—C2A—C3A | 179.25 (19) |
C2D—C1D—C6D—C5D | 1.4 (4) | C1A—C2A—C3A—N3A | 179.6 (2) |
C2D—C1D—C1Di—C6Di | −0.2 (4) | O2A—C2A—C3A—C4A | −176.7 (2) |
C6D—C1D—C1Di—C2Di | 0.2 (4) | C1A—C2A—C3A—C4A | 1.6 (3) |
C2D—C1D—C1Di—C2Di | 180.0 (2) | O2A—C2A—C3A—N3A | 1.3 (3) |
C1Di—C1D—C2D—C3D | 179.3 (2) | N3A—C3A—C4A—C5A | −179.7 (2) |
C1Di—C1D—C6D—C5D | −178.8 (2) | C2A—C3A—C4A—C5A | −1.7 (3) |
C6D—C1D—C2D—C3D | −0.9 (4) | C3A—C4A—C5A—N5A | −178.7 (2) |
C1D—C2D—C3D—C4D | 0.0 (4) | C3A—C4A—C5A—C6A | 0.8 (3) |
C2D—C3D—C4D—C5D | 0.5 (4) | N5A—C5A—C6A—C1A | 179.5 (2) |
C2D—C3D—C4D—N4D | −176.9 (2) | C4A—C5A—C6A—C1A | 0.0 (3) |
C3D—C4D—C5D—C6D | −0.1 (4) | C7B—C1B—C2B—O2B | −2.3 (3) |
N4D—C4D—C5D—C6D | 177.4 (2) | C6B—C1B—C2B—C3B | −3.5 (3) |
C4D—C5D—C6D—C1D | −0.9 (4) | C7B—C1B—C6B—C5B | −176.9 (2) |
C2C—C1C—C11C—C21C | −162.9 (2) | C7B—C1B—C2B—C3B | 174.5 (2) |
C6C—C1C—C11C—C61C | −166.5 (2) | C2B—C1B—C6B—C5B | 1.2 (3) |
C2C—C1C—C6C—C5C | −0.3 (3) | C6B—C1B—C7B—O71B | −0.8 (4) |
C2C—C1C—C11C—C61C | 15.7 (3) | C6B—C1B—C7B—O72B | 177.9 (2) |
C11C—C1C—C6C—C5C | −178.3 (2) | C2B—C1B—C7B—O71B | −178.9 (3) |
C6C—C1C—C11C—C21C | 15.0 (3) | C2B—C1B—C7B—O72B | −0.2 (4) |
C6C—C1C—C2C—C3C | 0.3 (4) | C6B—C1B—C2B—O2B | 179.6 (2) |
C11C—C1C—C2C—C3C | 178.3 (3) | O2B—C2B—C3B—N3B | 2.6 (3) |
C1C—C2C—C3C—C4C | 0.3 (5) | O2B—C2B—C3B—C4B | 179.8 (2) |
C2C—C3C—C4C—C5C | −0.9 (4) | C1B—C2B—C3B—N3B | −174.17 (19) |
C2C—C3C—C4C—N4C | −179.2 (3) | C1B—C2B—C3B—C4B | 3.0 (3) |
N4C—C4C—C5C—C6C | 179.2 (2) | C2B—C3B—C4B—C5B | 0.0 (3) |
C3C—C4C—C5C—C6C | 0.8 (3) | N3B—C3B—C4B—C5B | 177.25 (19) |
C4C—C5C—C6C—C1C | −0.2 (3) | C3B—C4B—C5B—C6B | −2.7 (3) |
C61C—C11C—C21C—C31C | −1.2 (3) | C3B—C4B—C5B—N5B | 177.7 (2) |
C1C—C11C—C21C—C31C | 177.4 (2) | N5B—C5B—C6B—C1B | −178.3 (2) |
C1C—C11C—C61C—C51C | −177.2 (2) | C4B—C5B—C6B—C1B | 2.1 (3) |
Symmetry code: (i) −x+1, −y+1, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O72A—H72A···O2A | 0.89 (3) | 1.62 (3) | 2.479 (3) | 161 (3) |
O72B—H72B···O2B | 0.92 (3) | 1.61 (3) | 2.487 (3) | 160 (3) |
O1E—H1E···O71Bii | 0.92 (3) | 1.79 (3) | 2.706 (3) | 175 (3) |
O1E—H1E···O72Bii | 0.92 (3) | 2.53 (3) | 3.165 (3) | 126 (3) |
N4C—H41C···O1Eiii | 0.89 (3) | 2.12 (3) | 2.903 (4) | 147 (3) |
N4C—H42C···O2Aiv | 0.95 (4) | 1.81 (4) | 2.761 (3) | 180 (4) |
N4C—H42C···O31Aiv | 0.95 (4) | 2.50 (4) | 2.870 (3) | 103 (3) |
N4C—H43C···O1Ev | 0.94 (3) | 1.85 (3) | 2.794 (4) | 176 (2) |
N4D—H41D···N41Cvi | 0.87 (2) | 1.99 (2) | 2.835 (3) | 162 (2) |
N4D—H42D···O2B | 0.95 (3) | 1.89 (3) | 2.838 (3) | 180 (3) |
N4D—H42D···O31B | 0.95 (3) | 2.51 (3) | 2.906 (3) | 105 (2) |
N4D—H43D···O71Avii | 0.96 (3) | 1.82 (3) | 2.781 (3) | 180 (3) |
N41C—H44C···O52Aviii | 0.92 (3) | 2.33 (3) | 3.133 (4) | 146 (3) |
N41C—H45C···O31Bv | 0.87 (3) | 2.49 (3) | 3.356 (4) | 176 (3) |
Symmetry codes: (ii) x+1, y, z; (iii) x−1, −y+3/2, z+1/2; (iv) x, −y+3/2, z+1/2; (v) −x+1, y+1/2, −z+1/2; (vi) x, y−1, z; (vii) −x+1, y−1/2, −z+1/2; (viii) x, −y+3/2, z−1/2. |
Experimental details
Crystal data |
Chemical formula | C12H14N22+·2C12H13N2+·4C7H3N2O7−·2C2H6O |
Mr | 1557.34 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 295 |
a, b, c (Å) | 18.862 (2), 10.5138 (11), 19.081 (2) |
β (°) | 109.154 (2) |
V (Å3) | 3574.6 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.45 × 0.15 × 0.08 |
|
Data collection |
Diffractometer | Bruker SMART CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 22178, 8165, 3072 |
Rint | 0.063 |
(sin θ/λ)max (Å−1) | 0.651 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.098, 0.87 |
No. of reflections | 8165 |
No. of parameters | 549 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.19, −0.15 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O72A—H72A···O2A | 0.89 (3) | 1.62 (3) | 2.479 (3) | 161 (3) |
O72B—H72B···O2B | 0.92 (3) | 1.61 (3) | 2.487 (3) | 160 (3) |
O1E—H1E···O71Bi | 0.92 (3) | 1.79 (3) | 2.706 (3) | 175 (3) |
O1E—H1E···O72Bi | 0.92 (3) | 2.53 (3) | 3.165 (3) | 126 (3) |
N4C—H41C···O1Eii | 0.89 (3) | 2.12 (3) | 2.903 (4) | 147 (3) |
N4C—H42C···O2Aiii | 0.95 (4) | 1.81 (4) | 2.761 (3) | 180 (4) |
N4C—H42C···O31Aiii | 0.95 (4) | 2.50 (4) | 2.870 (3) | 103 (3) |
N4C—H43C···O1Eiv | 0.94 (3) | 1.85 (3) | 2.794 (4) | 176 (2) |
N4D—H41D···N41Cv | 0.87 (2) | 1.99 (2) | 2.835 (3) | 162 (2) |
N4D—H42D···O2B | 0.95 (3) | 1.89 (3) | 2.838 (3) | 180 (3) |
N4D—H42D···O31B | 0.95 (3) | 2.51 (3) | 2.906 (3) | 105 (2) |
N4D—H43D···O71Avi | 0.96 (3) | 1.82 (3) | 2.781 (3) | 180 (3) |
N41C—H44C···O52Avii | 0.92 (3) | 2.33 (3) | 3.133 (4) | 146 (3) |
N41C—H45C···O31Biv | 0.87 (3) | 2.49 (3) | 3.356 (4) | 176 (3) |
Symmetry codes: (i) x+1, y, z; (ii) x−1, −y+3/2, z+1/2; (iii) x, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+1/2; (v) x, y−1, z; (vi) −x+1, y−1/2, −z+1/2; (vii) x, −y+3/2, z−1/2. |
3,5-Dinitrosalicylic acid (DNSA) has proved to be a particularly useful compound for the promotion of the crystallization of Lewis bases as chemically stable proton-transfer compounds. We have previously determined the crystal structures of more than 40 of these compounds (Smith et al., 1995, 2002, 2003, 2006) while adduct formation has been found with molecules such as urea (Smith et al., 1997), 1,1-diethylurea (Smith et al., 2000) and phenazine (Kumar et al., 2002). These are analogous to the set of pseudopolymorphic solvates formed with DNSA, namely two monohydrates (Smith et al., 1995; Kumar et al., 1999), four dioxine solvates and a tert-butyl alcohol solvate (Kumar et al., 1999). However, among the proton-transfer compounds of DNSA for which the crystal structures are known, only rarely are solvates formed, although most compounds are obtained from ethanol or ethanol–water mixtures. The only known examples of solvates are 2-aminopyridinium–3,5-dinitrosalicylate–ethanol (4/4/1) (Smith et al., 2002) and brucinium 3,5-dinitrosalicylate monohydrate (Smith et al., 2006). Generally, reaction of DNSA with aniline-type Lewis bases results in the formation of 1:1 anilinium cations, which usually enhance molecular self-assembly through extensive hydrogen-bonding interactions. Seldom are π–π interactions significant in this process, occurring only among polycyclic heteroaromatic Lewis base–DNSA compounds (Smith et al., 2006).
To extend the investigation of the systematics of the hydrogen bonding in proton-transfer compounds of DNSA with Lewis bases, we decided to prepare and crystallographically characterize the compounds with certain aromatic polyamines. The 1:1 and 2:1 compounds of DNSA with 1,1'-biphenyl-4,4'-diamine (benzidine, BD) had been synthesized and investigated spectroscopically by Issa et al. (1981). However, our attempted preparation of the 1:1 compound in 80% ethanol–water solvent surprisingly gave instead the compound reported here, the ethanol solvate of the proton-transfer compound, (I), which contains both dicationic and monocationic benzidine cation species, and corresponds to neither of the compounds reported by Issa et al. (1981). Compound (I) is best described in terms of the centrosymmetric molecular unit, [BD2+·2(BD+)·4(DNSA−)·2(EtOH)] (Fig. 1). The crystallographic asymmetric unit of (I) comprises two DNSA anions (anions A and B), a BD+ monocation (cation C), a BD2+ dication (cation D) lying across an inversion centre in the cell, and a disordered ethanol molecule of solvation (molecule E). The methyl group of the ethanol molecule occupies two partial sites, C2E [0.806 (17) occupancy] and C21E [0.194 (17) occupancy]. The monoprotonated C cations differ conformationally from the essentially planar doubly protonated D cations [C2C—C1C—C11C—C61C = 15.7 (3)°, cf. 0.2 (4)° for the equivalent angle in D]. The six aminium H atoms on cation D are involved in eight hydrogen-bonding interactions, viz. six to DNSA anions (carboxyl, phenol and nitro groups) and two to the unprotonated N-acceptors of benzidine cations C (Table 1). Included in this set is the primary linear H(aminium)···O(carboxyl) interaction [N4D—H43D···O71Avi; symmetry code: (vi) −x + 1, y − 1/2, −z + 1/2], whereas the carboxyl group of the second DNSA anion is not involved in any such interaction. Instead it forms a three-centred asymmetric R21(4) interaction with the hydroxyl H atom of the ethanol molecule of solvation [O1E—H1E··· O71Bi,O72Bi; symmetry code: (i) x + 1, y, z]. Anion C participates in four interactions via the protonated amine group (N4C), including two to ethanol (E) molecules. The unprotonated amine (N41C) forms only weak interactions with O atoms of the nitro groups but acts as an acceptor to a C-cation aminium H atom.
The result is a stable three-dimensional cage structure (Fig. 2), which has in addition significant π–π interactions between adjacent DNSA anion species [A···B; the ring centroid separation (CgA···CgB) is 3.605 (3) Å; the dihedral angle (α) is 4.7 (1)°] and A-anion–unprotonated C-cation species [CgA···CgC = 3.753 (3) Å and α = 6.2 (1)°]. Similar interactions have been found in the structures of a number of benzidine compounds (Herbstein, 1971), where it was observed that in the formation of ternary complexes involvement of the third species in π bonding did not occur. This is apparent in the series of pseudopolymorphic 1:1 benzidene complexes with 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), the solvent-free complex (Yakushi et al., 1974a), the benzene solvate (Yakushi et al., 1974b) and the dichloromethane solvate (Ikemoto et al., 1972). These structures are somewhat analogous to the structure of (I), where, in addition, it would appear that the lack of flexibility of the protonated benzidine molecule together with the enforced π–π interactions place constraints on the availability of suitable O-acceptor sites on DNSA, resulting in the incorporation of the unusual molecule of ethanol in the structure. As indicated previously, ethanol or water solvent molecules are rare in DNSA proton-transfer compounds and it can only be speculated that ethanol incorporation in (I) (rather than water) has to do with a space-filling requirement.
With the DNSA anions, the expected intramolecular hydrogen bond is found between the phenol and carboxylate substituent groups of the DNSA anions [O72—H72···O2 = 2.479 (3) Å [−173.2 (2)?] (A) and 2.487 (3) Å (B)], with the H atoms located on the carboxylate O atoms. The carboxyl group is therefore essentially coplanar with the benzene ring [C2—C1—C7—O71 = 177.6 (2) [−173.2 (2)?] (A) and −178.9 (3)° (B)], as are the nitro substituent groups at C5 [C4—C5—N5—O52 = −177.8 (2) (A) and −175.7 (2)° (B)]. However, in both anion species, the nitro group at C3 is rotated out of the plane [C2—C3—N3—O32 = −149.5 (3) (A) and 147.7 (2)° (B)].