Hydrogen bonding in two benzene-1,2-diaminium pyridine-2-carboxylate salts and a cocrystal of benzene-1,2-diamine and benzoic acid

Article abstract of DOI:10.1107/S2053229619002262

The isostructural salts benzene-1,2-diaminium bis(pyridine-2-carboxylate), 0.5C₆H₁₀N₂²⁺·C₆H₄NO₂^?, (1), and 4,5-dimethylbenzene-1,2-diaminium bis(pyridine-2-carboxylate

Full text of DOI:10.1107/S2053229619002262

research papers
Hydrogen bonding in two benzene-1,2-diaminium
pyridine-2-carboxylate salts and a cocrystal of
benzene-1,2-diamine and benzoic acid
ISSN 2053-2296
Kyle A. Powers and David K. Geiger*
Department of Chemistry, SUNY-College at Geneseo, Geneseo, NY 14454, USA. *Correspondence e-mail:
geiger@geneseo.edu
Received 18 December 2018
Accepted 11 February 2019
The isostructural salts benzene-1,2-diaminium bis(pyridine-2-carboxylate),
2+
Edited by P. Fanwick, Purdue University, USA
0.5C6H10N2 ꢀC6H4NO2ꢁ, (1), and 4,5-dimethylbenzene-1,2-diaminium bis(pyri-
2+
dine-2-carboxylate), 0.5C8H14N2 ꢀC6H4NO2ꢁ, (2), and the 1:2 benzene-1,2-
Keywords: density functional theory; DFT;
Hirshfeld plots; crystal structure; interaction
energy; hydrogen bonds; diamine.
diamine–benzoic acid cocrystal, 0.5C6H8N2ꢀC7H6O2, (3), are reported. All of the
compounds exhibit extensive N—Hꢀ ꢀ ꢀO hydrogen bonding that results in
interconnected rings. O—Hꢀ ꢀ ꢀN hydrogen bonding is observed in (3).
Additional ꢀ–ꢀ and C—Hꢀ ꢀ ꢀꢀ interactions are found in each compound.
Hirshfeld and fingerprint plot analyses reveal the primary intermolecular
interactions and density functional theory was used to calculate their strengths.
Salt formation by (1) and (2), and cocrystallization by (3) are rationalized by
examining pKa differences. The R22(9) hydrogen-bonding motif is common to
each of these structures.
CCDC references: 1896669; 1896668;
1896667
Supporting information: this article has
supporting information at journals.iucr.org/c
1. Introduction
Hydrogen bonding plays an important role in the strategic
design of solid-state structures with desirable architectures.
Weaker intermolecular interactions (e.g. those involving
ꢀ-stacking and/or C—Hꢀ ꢀ ꢀꢀ interactions) can play a role in
the self-assembly process, leading to nucleation and crystal
growth, as well as cocrystal versus salt formation (Bora et al.,
2018). An understanding of the relative strengths of these
interactions is of importance in the preparation of pharma-
ceuticals with consistent formulations (Anderson et al., 2009;
Thakuria et al., 2007). When a formulation contains a weak
acid and a weak base, the analytical characteristics of the
components (i.e. relative acid/base strength) is a decisive
determinant of salt versus cocrystal formation (Rajput et al.,
2017; Cruz-Cabeza, 2012).
The synthon benzene-1,2-diamine and its analogues provide
multiple sites in close proximity for hydrogen bonding and an
aromatic system with the potential to engage in ꢀ–ꢀ and C—
Hꢀ ꢀ ꢀꢀ interactions (Deng et al., 2012). We have taken
advantage of these attributes to prepare a variety of coordi-
nation polymers containing benzenediamine ligands (Geiger
et al., 2016; Geiger, Parsons & Zick, 2014; Geiger & Parsons,
2014).
We recently reported the preparation, structural char-
acterization and calculated interaction energies of several
protonated benzenediamines with inorganic anions (Zick &
Geiger, 2018). Herein, we explore the structures of two
isostructural salts, namely, benzene-1,2-diaminium bis(pyri-
dine-2-carboxylate), (1), and 4,5-dimethylbenzene-1,2-diami-
nium bis(pyridine-2-carboxylate), (2). We also report the 1:2
benzene-1,2-diamine–benzoic acid cocrystal, (3). The results
# 2019 International Union of Crystallography
Acta Cryst. (2019). C75
https://doi.org/10.1107/S2053229619002262 1 of 7

research papers
Table 1
Experimental details.
(1)
(2)
(3)
Crystal data
Chemical formula
Mr
2+
0.5C6H10N2 ꢀC6H4NO2
ꢁ
2+
0.5C8H14N2 ꢀC6H4NO2
ꢁ
0.5C6H8N2ꢀC7H6O2
176.19
177.18
191.21
Crystal system, space group
Temperature (K)
Monoclinic, C2/c
200
21.467 (5), 7.675 (2), 12.837 (3)
Monoclinic, C2/c
200
21.451 (4), 9.0100 (19), 12.585 (3)
Orthorhombic, Pbcn
200
20.061 (3), 7.8464 (10),
11.6895 (12)
90, 90, 90
1840.0 (4)
8
Mo Kꢂ
0.09
˚
a, b, c (A)
ꢂ, ꢃ, ꢄ (ꢃ)
90, 125.362 (7), 90
1724.8 (7)
8
Mo Kꢂ
0.10
0.50 ꢄ 0.30 ꢄ 0.25
90, 123.447 (6), 90
2029.5 (7)
8
Mo Kꢂ
0.09
0.60 ꢄ 0.50 ꢄ 0.25
3
˚
V (A )
Z
Radiation type
ꢅ (mmꢁ1
Crystal size (mm)
)
0.60 ꢄ 0.48 ꢄ 0.20
Data collection
Diffractometer
Bruker SMART X2S benchtop
Bruker SMART X2S benchtop
diffractometer
Bruker SMART X2S benchtop
Absorption correction
Multi-scan (SADABS; Bruker,
2015)
0.61, 0.98
Multi-scan (SADABS; Bruker,
2015)
0.61, 0.98
Multi-scan (SADABS; Bruker,
2015)
0.64, 0.98
Tmin, Tmax
No. of measured, independent and
observed [I > 2ꢆ(I)] reflections
Rint
8287, 1573, 1161
7764, 1794, 1201
30170, 1638, 1337
0.063
0.602
0.080
0.603
0.064
0.598
ꢁ1
˚
(sin ꢇ/ꢈ)max (A
)
Refinement
R[F2 > 2ꢆ(F2)], wR(F2), S
No. of reflections
0.047, 0.138, 1.04
1573
0.044, 0.128, 1.01
1794
0.030, 0.087, 1.05
1638
No. of parameters
No. of restraints
H-atom treatment
130
3
140
3
131
0
H atoms treated by a mixture of
independent and constrained
refinement
0.20, ꢁ0.26
H atoms treated by a mixture of
independent and constrained
refinement
H atoms treated by a mixture of
independent and constrained
refinement
0.12, ꢁ0.12
ꢁ3
˚
Áꢉmax, Áꢉmin (e A
)
0.14, ꢁ0.19
Computer programs: APEX2 (Bruker, 2015), SAINT (Bruker, 2015), SHELXS97 (Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015), PLATON (Spek, 2009), Mercury (Macrae et al.,
2008), and publCIF (Westrip, 2010).
of an exploration of the primary intermolecular interactions,
including the calculation of hydrogen bond, ꢀ–ꢀ, and C—
Hꢀ ꢀ ꢀꢀ energies, are reported.
stirring until the solid was dissolved. 2-Picolinic acid (2.30 g)
was added to the reaction mixture with continued heating and
stirring. The mixture was stirred at room temperature for a
week. A white precipitate formed. The product (2.59 g) was
collected by vacuum filtration (78.9% yield). 1H NMR
(400 MHz, DMSO, ppm): ꢁ 8.67 (d, 2H), 8.02 (d, 2H), 7.96 (t,
2H), 7.58 (t, 2H), 6.55 (s, 2H), 6.43 (s, 2H). Single crystals were
obtained via vapor diffusion of hexane into an ethyl acetate
solution of the product at room temperature.
2.1.2. Preparation of 4,5-dimethylbenzene-1,2-diaminium
bis(pyridine-2-carboxylate), (2). 4,5-Dimethylbenzene-1,2-di-
amine (1.10 g) was dissolved in absolute ethanol (20 ml) with
stirring. A solution of 2-picolinic acid (2.00 g) in absolute
ethanol (20 ml) was added with stirring. The resulting mixture
was stirred for a week, during which time a pink-colored
precipitate formed. The product (yield 2.52 g, 81.7%) was
1
collected by vacuum filtration. H NMR (400 MHz, DMSO,
ppm): ꢁ 8.66 (d, 2H), 8.02 (d, 2H), 7.95 (t, 2H), 7.59 (t, 2H), 6.35
(s, 2H), 1.96 (s, 6H). Single crystals were obtained via slow
evaporation of a solution of the product in ethyl acetate at
room temperature.
2. Experimental
2.1. Synthesis and crystallization
2.1.1. Preparation of benzene-1,2-diaminium bis(pyridine-
2-carboxylate), (1). Benzene-1,2-diamine (1.00 g) was added
to absolute ethanol (30 ml). The mixture was heated with
2.1.3. Preparation of benzene-1,2-diamine–benzoic acid
(1/2), (3). Benzene-1,2-diamine (1.60 g) was dissolved in
absolute ethanol (45 ml) with heating and stirring. Benzoic
ꢂ
2 of 7 Powers and Geiger
Hydrogen bonding in benzene-1,2-diamine salts and cocrystal
Acta Cryst. (2019). C75

research papers
acid (3.60 g) was added to the reaction mixture. Heating was
stopped once the reagents dissolved, and the mixture was
stirred at room temperature for a week. Ethanol (20 ml) was
removed via rotary evaporation and hexane (15 ml) was
added. After chilling, an orange precipitate formed. The
product (yield 0.81 g, 15.7%) was collected by vacuum filtra-
tion. 1H NMR (400 MHz, DMSO, ppm): ꢁ 7.91 (d, 4H), 7.58 (t,
2H), 7.47 (t, 4H), 6.53 (m, 2H), 6.40 (m, 2H). Single crystals
were obtained via vapor diffusion of hexane into a chloroform
solution of the product at room temperature.
normalized values determined by neutron diffraction results
(Allen et al., 2004) for (1) and (2). An additional pyridine-2-
carboxylate was included in interaction energy calculations for
(1) and (2) in order to maintain charge neutrality. For (3),
H-atom positions were optimized to their energy minima using
the M06-2X/6-31G(d,p) functional/basis set combination.
3. Results and discussion
Compounds (1) and (2) are isostructural salts. Views of (1) and
(2) displaying the atom-labeling schemes are shown in Figs. 1
and 2. The cation resides across a crystallographically imposed
twofold rotation axis and the asymmetric unit contains the
pyridine-2-carboxylate (paꢁ) anion and one-half of the
benzene-1,2-diaminium (bdaH22+) dication for (1) and the 4,5-
dimethylbenzene-1,2-diaminium (Me2bdaH22+) dication for
(2). A search of the Cambridge Structural Database (CSD;
Groom et al., 2016) yielded only one organic structure con-
taining a benzene-1,2-diaminium moiety (CSD refcode
ZEXBEM; Amirthakumar et al., 2018).
The hydrogen-bonding network for (1) is shown in Fig. 3.
An extensive ring system involving protonated amine donors
with a pyridine-ring N atom and carboxylate O atoms as
acceptors is observed. The carboxylate and diaminium
synthons result in R22(9) rings with each aminium group as
donor to a different oxygen acceptor. An R21(5) ring is the
product of a bifurcated aminium donor with a pyridine N atom
and one of the carboxylate O atoms as acceptors. This
hydrogen-bonding motif has been observed for other pyri-
2.2. Refinement
Crystal data, data collection and structure refinement
details are summarized in Table 1. For all compounds, H atoms
bonded to C atoms were refined using a riding model, with
˚
C—H = 0.95 A for aromatic C atoms and, for (2), C—H =
˚
0.98 A for methyl H atoms. For all structures, Uiso(H) =
kUeq(C), where k = 1.2 for H atoms bonded to aromatic C
atoms and 1.5 for H atoms bonded to methyl C atoms. For (1)
˚
and (2), the N—H bond lengths were restrained to 0.91 (2) A;
for (3), the N—H bond lengths were refined freely. For all
compounds, the isotropic diplacement parameters of the H
atoms bonded to N and O atoms were refined freely.
Large K values were noted in the analysis of variance for (1)
and (2). However, the K value is large only for weak reflec-
tions [Fc/Fc(max) is lower than 0.005 for (1) and 0.020 for (2)].
2.3. Hirshfeld surface, fingerprint plots, and interaction
energy calculations
Hirshfeld surfaces, fingerprint plots, interaction energies,
and energy frameworks (Turner et al., 2015) were calculated
using CrystalExplorer17 (Turner et al., 2017). Interaction
energies for (3) were calculated employing the CE-B3LYP/6-
31G(d,p) functional/basis set combination and are corrected
for basis set superposition energy (BSSE) using the counter-
poise (CP) method (Boys & Bernardi, 1970). The interaction
energy is broken down as
˙
dine-2-carboxylate salts (Zesławska et al., 2017). A third ring,
R24(8), involves a single O atom from two different carboxylate
acceptors and a single aminium group from two different
cations, each behaving as a two-H-atom donor. The joined
rings propagate along [001].
A weak ꢀ–ꢀ interaction is observed in (1) with
ꢁ
ꢁ
ꢁ
˚
Cg(pa )ꢀ ꢀ ꢀCg(pa ) = 3.9360 (16) A, where Cg(pa ) is the
pyridine ring centroid. The corresponding distance in (2) is
˚
4.6018 (15) A. As seen in Fig. 3, rings involved in the ꢀ-
Etot ¼ keleE0ele þ kpolE0pol þ kdisEd0 is þ krepE0rep
;
stacking are related by the twofold screw axes. The large
difference in stacking distance can be accounted for by the
disparity in the b-axis lengths (Table 1 and Fig. 4). Both (1)
where the k values are scale factors, E0ele represen0ts the
electrostatic component, E0pol the polarization energy, E dis the
dispersion energy, and E0rep the exchange–repulsion energy
(Turner et al., 2014; Mackenzie et al., 2017). The C—H bond
lengths were converted to normalized values based on neutron
diffraction results (Allen et al., 2004).
Interaction energy calculations were also performed on
molecules in the gas phase using SPARTAN’16 (Wavefunc-
tion, 2016). Density functional theory (DFT) calculations
using the M06-2X (Zhao & Truhlar, 2008) functional with a
6-31G(d,p) basis set were employed for the determination of
interaction energies, which were corrected for BSSE
employing the CP method (Boys & Bernardi, 1970). Atomic
coordinates obtained from the crystallographic analysis were
used for all non-H atoms. Because bond lengths obtained for
H atoms from X-ray crystallographic analyses are inaccurate,
the positions of the H atoms were adjusted based on
Figure 1
View of the molecular structure of (1), showing the atom-labeling scheme.
Displacement ellipsoids for non-H atoms are drawn at the 50%
3
probability level. [Symmetry code: (a) ꢁx + 1, y, ꢁz + .]
2
ꢂ
Acta Cryst. (2019). C75
Powers and Geiger
Hydrogen bonding in benzene-1,2-diamine salts and cocrystal 3 of 7

research papers
Table 2
Hydrogen-bond geometry (A, ) for (1).
ꢃ
˚
Cg(bdaH22+) refers to the ring centroid of the benzene-1,2-diaminium cation.
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N1—H1Aꢀ ꢀ ꢀO1i
N1—H1Aꢀ ꢀ ꢀN2i
N1—H1Bꢀ ꢀ ꢀO2ii
N1—H1Cꢀ ꢀ ꢀO1
C8—H8ꢀ ꢀ ꢀCg(bdaH2
0.93 (2)
0.93 (2)
0.96 (2)
0.97 (2)
0.95
2.24 (2)
2.08 (2)
1.78 (2)
1.70 (2)
2.65
2.958 (2)
2.907 (2)
2.7137 (19)
2.6533 (19)
3.592 (3)
135 (2)
149 (2)
164 (2)
168 (2)
170
2+ iii
)
3
2
1
1
Symmetry codes: (i) ꢁx þ 1; ꢁy þ 1; ꢁz þ 1; (ii) ꢁx þ 1; y; ꢁz þ ; (iii) x þ ; y ꢁ ; z.
2
2
Figure 2
View of the molecular structure of (2), showing the atom-labeling scheme.
Table 3
Hydrogen-bond geometry (A, ) for (2).
ꢃ
˚
The atomic coordinates of the carboxylate anion have been transformed
1
Cg(Me2bdaH22+) refers to the ring centroid of the 4,5-dimethylbenzene-1,2-
diaminium cation.
by (ꢁx + 1, y ꢁ 1, ꢁz + ) to show hydrogen bonding. Displacement
2
ellipsoids for non-H atoms are drawn at the 50% probability level.
1
2
[Symmetry code: (a) ꢁx + 1, y, ꢁz + .]
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N2—H2Aꢀ ꢀ ꢀO2i
N2—H2Cꢀ ꢀ ꢀO1iii
N2—H2Cꢀ ꢀ ꢀN1iii
C5—H5ꢀ ꢀ ꢀCg(Me2bdaH2
0.96 (2) 1.78 (2) 2.729 (2)
0.98 (2) 1.67 (2) 2.639 (2)
0.91 (1) 2.14 (2) 2.9032 (19) 141 (2)
171 (2)
169 (2)
and (2) exhibit a weak C—Hꢀ ꢀ ꢀꢀ interaction involving a H
atom belonging to the anion and the cation ꢀ-system (Tables 2
and 3). Together, the C—Hꢀ ꢀ ꢀꢀ and the ꢀ–ꢀ contacts result in
chains parallel to [110].
The Hirshfeld surface and fingerprint plots of (1) are shown
in Fig. 5 and of (2) are in the supporting information. The
surface coverage for bdaH22+and baꢁ are, respectively, Hꢀ ꢀ ꢀH
39.0 and 29.0%, Cꢀ ꢀ ꢀC 0.0 and 9.7%, Nꢀ ꢀ ꢀH 9.7 and 7.2%,
Oꢀ ꢀ ꢀH 32.7 and 34.6%, Cꢀ ꢀ ꢀH 18.4 and 16.9%, and Nꢀ ꢀ ꢀC 0.0
and 3.4%. The primary intermolecular interactions are clearly
observable in the fingerprint plot.
N2—H2Bꢀ ꢀ ꢀO1ii
0.91 (1) 2.22 (2) 2.999 (2)
0.95 2.77 3.682 (3)
144 (2)
160
2+ iv
)
1
2
Symmetry codes: (i) ꢁx þ 1; y ꢁ 1; ꢁz þ ; (ii) x; y ꢁ 1; z; (iii) ꢁx þ 1; ꢁy þ 1; ꢁz þ 1;
1
2
1
2
(iv) x ꢁ ; y þ ; z.
asymmetric unit contains one molecule of ba and one-half
molecule of bda. A view of (3) showing the atom-labeling
scheme is shown in Fig. 6. Searches of the CSD for related
structures containing benzoic acid or benzene-1,2-diamine
yielded a total of three results [CSD refcodes VOCZET02
(Meng et al., 2009), URILAJ (Landenberger & Matzger,
2010), and ZEZHOD (Landenberger & Matzger, 2012)].
Compound (3) is a 1:2 cocrystal of benzene-1,2-diamine
(bda) and benzoic acid (ba). The bda resides across a crys-
tallographically imposed twofold rotation axis. As a result, the
Figure 3
Partial packing diagram of (1), showing the hydrogen bonding resulting in strips along [001]. Only H atoms involved in the interactions are shown. For
symmetry codes, see Table 2; additionally, (iv) ꢁx + 1, y, ꢁz + 32.
ꢂ
4 of 7 Powers and Geiger
Hydrogen bonding in benzene-1,2-diamine salts and cocrystal
Acta Cryst. (2019). C75

research papers
Figure 4
Partial packing diagram of (1), showing the ꢀ–ꢀ and C—Hꢀ ꢀ ꢀꢀ interactions leading to chains parallel to [110]. Only H atoms involved in these interations
3
2
1
2
1
2
1
2
3
2
are shown. [Symmetry codes: (i) ꢁx + 32, y + 21, ꢁz + 23; (ii) ꢁx + 1, y, ꢁz + ; (iii) x ꢁ , y + , z; (iv) ꢁx + 32, y ꢁ , ꢁz + .]
An extensive hydrogen-bonding network composed of both
N—Hꢀ ꢀ ꢀO and O—Hꢀ ꢀ ꢀN interactions exists. Alternating
R22(9) and R24(8) rings result in chains parallel to [001], as seen
in Table 4 and Fig. 7. In the R22(9) rings, both N—Hꢀ ꢀ ꢀO and
O—Hꢀ ꢀ ꢀN hydrogen bonds are found, whereas the R24(8) rings
are composed of only N—Hꢀ ꢀ ꢀO hydrogen bonds.
Table 4
Hydrogen-bond geometry (A, ) for (3).
ꢃ
˚
Cg(bda) refers to the ring centroid of the benzene-1,2-diamine ring.
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
O1—H1Cꢀ ꢀ ꢀN1
0.994 (19)
0.916 (15)
0.916 (16)
0.95
1.706 (19)
2.163 (16)
2.136 (16)
2.81
2.6852 (13)
3.0681 (14)
3.0160 (14)
3.7163 (16)
167.8 (16)
169.8 (12)
160.8 (12)
161
N1—H1Aꢀ ꢀ ꢀO2i
N1—H1Bꢀ ꢀ ꢀO2ii
C6—H6ꢀ ꢀ ꢀCg(bda)iii
In addition to N—Hꢀ ꢀ ꢀO and O–H-ꢀ ꢀ ꢀN hydrogen bonding,
the extended structure of (3) exhibits C—Hꢀ ꢀ ꢀꢀ interactions
(Table 4 and Fig. 8) in which the ba serves as the donor to the
bda ꢀ-ring. Finally, the superstructure exhibits a weak ꢀ–ꢀ
1
2
1
2
1
2
1
2
1
2
Symmetry codes: (i) x; ꢁy þ 1; z ꢁ ; (ii) ꢁx þ 1; y; ꢁz þ ; (iii) x ꢁ ; y þ ; ꢁz þ .
interaction between adjacent ba molecules, with
a
Cg(ba)ꢀ ꢀ ꢀCg(ba)iii distance of 4.0487 (10) A (see Table 4 for
˚
symmetry code).
The ÁpKa rule can be used to rationalize observed salt
formation versus cocrystallization of a weak acid and a weak
base. Simply stated, if the difference in pKa values of the acid
and base is greater than 3, proton transfer from acid to base
occurs resulting in salt formation. If the difference is less than
1, the acid remains protonated and cocrystallization results.
For ÁpKa values between 1 and 3, proton transfer is usually
incomplete, resulting in greater ambiguity, referred to as the
‘salt–cocrystal continuum’ (Rajput et al., 2017). In the present
case, pyridine-2-carboxylic acid, benzoic acid, benzene-1,2-
diaminium, and 4,5-dimethylbenzene-1,2-diaminium have pKa
Figure 6
View of the molecular structure of (3), showing the atom-labeling scheme.
Figure 5
(a) Hirshfeld surfaces and (b) fingerprint plots for (1). The diaminium
cation is on the left and the carboxylate anion is on the right.
Displacement ellipsoids for non-H atoms are drawn at the 50%
1
probability level. [Symmetry code: (a) ꢁx + 1, y, ꢁz + .]
2
ꢂ
Acta Cryst. (2019). C75
Powers and Geiger
Hydrogen bonding in benzene-1,2-diamine salts and cocrystal 5 of 7

research papers
Table 5
Interaction energies (kJ molꢁ1) calculated for (3).
Interaction energies were calculated employing the CE-B3LYP/6-31G(d,p)
functional/basis set combination and are corrected for BSSE using the CP
method.
Interaction(s)
E0ele
E0pol
E0dis
E0rep
Etot
O—Hꢀ ꢀ ꢀN/N—Hꢀ ꢀ ꢀO
N—Hꢀ ꢀ ꢀO
ꢀ–ꢀ
C—Hꢀ ꢀ ꢀꢀ
ꢁ98.5
ꢁ20.5
ꢁ2.7
ꢁ22.7
ꢁ4.4
ꢁ0.6
ꢁ1.0
ꢁ17.0
ꢁ9.2
119.5
20.2
11.7
7.3
ꢁ61.9
ꢁ20.5
ꢁ17.8
ꢁ12.1
ꢁ24.8
ꢁ13.3
ꢁ4.1
Scale factors used to determine Etot: kele = 1.057, kpol = 0.740, kdis = 0.871, and krep = 0.618
(Mackenzie et al., 2017). See Section 2.3 for calculation details.
values of 1.01, 4.20, 4.47, and 5.12, respectively (Dean, 1985;
Haynes, 2010). The resulting ÁpKa values for (1), (2) and (3)
are thus 3.46, 4.11 and 0.27, respectively. As predicted using
the ÁpKa rule, (1) and (2) are salts and (3) is a cocrystal.
Hirshfeld and fingerprint plots (Mackenzie et al., 2017) for
(3) are shown in Fig. 9. The principal interactions are clearly
visible in the fingerprint plots. The surface coverage for bda
and ba are, respectively, Hꢀ ꢀ ꢀH 59.7 and 40.4%, Cꢀ ꢀ ꢀC 0 and
9.8%, Nꢀ ꢀ ꢀH 5.4 and 2.6%, Oꢀ ꢀ ꢀH 17.0 and 23.8%, Cꢀ ꢀ ꢀH 17.9
and 21.3%, and Cꢀ ꢀ ꢀO 0.1 and 2.0%.
Figure 8
Partial packing diagram of (3), emphasizing the ꢀ–ꢀ and C—Hꢀ ꢀ ꢀꢀ
interactions. Only H atoms involved in these interations are shown.
[Symmetry codes: (i) x + 21, y ꢁ , ꢁz + 21; (ii) ꢁx + 21, y ꢁ , z; (iii) ꢁx + 21,
1
2
1
2
1
y + , z.]
2
Using SPARTAN’16 (Wavefunction, 2016) and the M06-2X
functional, as described in Section 2.3, value of
a
ꢁ56.0 kJ molꢁ1 was obtained for the R22(9) ring interactions
and a value of ꢁ20.6 kJ for the N—Hꢀ ꢀ ꢀO interaction in the
R24(8) ring. The M06 suite of density functionals are reported
to outperform B3LYP for dispersion and ionic hydrogen-
bonding interactions (Walker et al., 2013; Zhao & Truhlar,
2008; Zick & Geiger, 2018). For comparison, a value of
Interaction energies for (3) were calculated using two
different methods, as described in Section 2.3. The results for
the principal intermolecular interactions obtained using
CrystalExplorer (Turner et al., 2014; Mackenzie et al., 2017) are
shown in Table 5. The O—Hꢀ ꢀ ꢀN and N—Hꢀ ꢀ ꢀO hydrogen-
bonding interactions that result in the R22(9) rings
(ꢁ61.9 kJ molꢁ1) are stronger than the two N—Hꢀ ꢀ ꢀO inter-
actions resulting in the R42(8) rings (ꢁ20.5 kJ molꢁ1 each). As
expected for a traditional hydrogen bond, the primary
contributor to the total energy is the electrostatic component.
Figure 7
Partial packing diagram of (3), showing the linked chains parallel to [001].
Figure 9
(a) Hirshfeld surfaces and (b) fingerprint plots for (3). The benzene-1,2-
diamine molecule is on the left and the benzoic acid molecule is on the
right.
Only H atoms involved in these interactions are shown. [Symmetry codes:
1
1
(i) ꢁx + 1, y, ꢁz + ; (ii) x, ꢁy + 1, z ꢁ .]
2
2
ꢂ
6 of 7 Powers and Geiger
Hydrogen bonding in benzene-1,2-diamine salts and cocrystal
Acta Cryst. (2019). C75

research papers
ꢁ70.3 kJ molꢁ1 has been reported for the R22(8) ring com-
posed of two fused pyridine rings as acceptors and two fused
4-pyridone rings as donors, i.e. two N—Hꢀ ꢀ ꢀN interactions
(Rozas, 2007). In the same study, an interaction energy of
ꢁ47.2 kJ molꢁ1 was calculated for an R12(6) ring composed of a
pyridine acceptor and a fused 4-pyridone donor (i.e. two N—H
donors and one N-atom acceptor) and ꢁ42.09 kJ molꢁ1 for a
four-membered ring with a bifurcated hydrogen bond (a
4-pyridone donor and two fused pyridine rings as acceptors).
A value of ꢁ94.9 kJ molꢁ1 obtained using the M06-2X func-
tional has been reported for an N—Hꢀ ꢀ ꢀN interaction
between two benzene-1,3-diaminium cations (Zick & Geiger,
2018) and a value of ꢁ79.5 kJ molꢁ1 was reported for
[H2Nꢀ ꢀ ꢀHꢀ ꢀ ꢀNH3]+ (Steiner, 2002).
Amirthakumar, C., Pandi, P., Kumar, R. M. & Chakkaravarthi, G.
(2018). IUCrData, 3, x180437.
Anderson, K. M., Probert, M. R., Whiteley, C. N., Rowland, A. M.,
Goeta, A. E. & Steed, J. W. (2009). Cryst. Growth Des. 9, 1082–
1087.
Bora, P., Saikia, B. & Sarma, B. (2018). Cryst. Growth Des. 18, 1448–
1458.
Boys, S. F. & Bernardi, F. (1970). Mol. Phys. 19, 553–566.
Bruker (2015). APEX2, SAINT and SADABS. Bruker AXS Inc.,
Madison, Wisconsin, USA.
Cruz-Cabeza, A. J. (2012). CrystEngComm, 14, 6362–6365.
Dean, J. A. (1985). Lange’s Handbook of Chemistry, 13th ed., pp.
5-14–5-60. New York: McGraw-Hill.
Defazio, S., Tamasi, G. & Cini, R. (2005). C. R. Chim. 8, 1584–1609.
Deng, Z.-P., Huo, L.-H., Zhao, H. & Gao, S. (2012). Cryst. Growth
Des. 12, 3342–3355.
Geiger, D. K., Geiger, H. C. & Deck, J. M. (2014). Acta Cryst. C70,
1125–1132.
Geiger, D. K. & Parsons, D. E. (2014). Acta Cryst. E70, m247–m248.
Geiger, D. K., Parsons, D. E. & Pagano, B. A. (2016). Acta Cryst. E72,
1718–1723.
Geiger, D. K., Parsons, D. E. & Zick, P. L. (2014). Acta Cryst. E70,
566–572.
Grimme, S. (2008). Angew. Chem. Int. Ed. 47, 3430–3434.
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta
Cryst. B72, 171–179.
Haynes, W. M. (2010). In CRC Handbook of Chemistry and Physics,
91st ed. Boca Raton: CRC Press.
Landenberger, K. B. & Matzger, A. J. (2010). Cryst. Growth Des. 10,
5342–5347.
Landenberger, K. B. & Matzger, A. J. (2012). Cryst. Growth Des. 12,
3603–3609.
Mackenzie, C. F., Spackman, P. R., Jayatilaka, D. & Spackman, M. A.
(2017). IUCrJ, 4, 575–587.
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe,
P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. &
Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.
Meng, A.-L., Huang, J.-E., Zheng, B. & Li, Z.-J. (2009). Acta Cryst.
E65, o1595.
Rajput, L., Banik, M., Yarava, J. R., Joseph, S., Pandey, M. K.,
Nishiyama, Y. & Desiraju, G. R. (2017). IUCrJ, 4, 466–475.
Rozas, I. (2007). Phys. Chem. Chem. Phys. 9, 2782–2790.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Sheldrick, G. M. (2015). Acta Cryst. A71, 3–8.
Sherrill, C. D., Takatani, T. & Hohenstein, E. G. (2009). J. Phys.
Chem. A, 113, 10146–10159.
Spek, A. L. (2009). Acta Cryst. D65, 148–155.
Steiner, R. (2002). Angew. Chem. Int. Ed. 41, 48–76.
Thakuria, H., Borah, B. M., Pramanik, A. & Das, G. (2007). J. Chem.
Crystallogr. 37, 807–816.
Turner, M. J., Grabowsky, S., Jayatilaka, D. & Spackman, M. A.
(2014). J. Phys. Chem. Lett. 5, 4249–4255.
The C—Hꢀ ꢀ ꢀꢀ (ꢁ12.1 kJ molꢁ1) and ꢀ–ꢀ (ꢁ17.8 kJ molꢁ1
)
interactions are dominated by the dispersion energy. Although
much weaker than the calculated traditional hydrogen-bond
energies, these values compare favorably with the value of
ꢁ7.7 kJ molꢁ1 for a C—Hꢀ ꢀ ꢀꢀ interaction between furan
molecules (Geiger, Geiger
& Deck, 2014) and the
ꢁ9.4 kJ molꢁ1 reported for a ‘T-shaped’ benzene dimer
(Sherrill et al., 2009). A value of ꢁ20.7 kJ molꢁ1 was reported
for a ꢀ–ꢀ interaction between benzene rings of a benzimidazole
derivative (Geiger, Geiger & Deck, 2014) and ꢁ11 kJ molꢁ1
for benzene rings in a coplanar orientation (Grimme, 2008).
Calculations were also performed on (1) and (2) to estimate
the charge-assisted hydrogen-bonding energy between the
diaminium cation and the carboxylate counter-ion. For the
R22(9) ring (two N—Hꢀ ꢀ ꢀO), the BSSE-corrected interaction
energies found were ꢁ546 and ꢁ543 kJ molꢁ1 for (1) and (2),
respectively. The values obtained for the R21(5) ring (bifur-
cated N—Hꢀ ꢀ ꢀN,O) were ꢁ412 and ꢁ437 kJ molꢁ1. The
results suggest that the slight difference in basicities of the two
diamines does not play a major role in determining the
strengths of these hydrogen bonds. These values are less than
that of ꢁ665 kJ molꢁ1 found for the charge-assisted N—
Hꢀ ꢀ ꢀO hydrogen bonds in 3-aminoanilinium perchlorate (Zick
& Geiger, 2018) and are close to the values found for the
methylammoniumꢀ ꢀ ꢀClꢁ and methylamineꢀ ꢀ ꢀClꢁ energies, i.e.
ꢁ507 and ꢁ413 kJ molꢁ1, respectively (Defazio et al., 2005).
The results demonstrate that an aromatic-1,2-diamine and a
carboxylic acid combine in an energetically favorable way to
form a tecton with an R22(9) motif, regardless of the formation
of a salt (i.e. deprotonation of the acid/protonation of the
amine) or cocrystallization.
Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J.,
Spackman, P. R., Jayatilaka, D. & Spackman, M. A. (2017).
CrystalExplorer17. University of Western Australia. http://crystal-
explorer.scb.uwa.edu.au.
Turner, M. J., Thomas, S. P., Shi, M. W., Jayatilaka, D. & Spackman, M.
A. (2015). Chem. Commun. 51, 3735–3738.
Acknowledgements
This work was supported by a Congressionally directed grant
from the US Department of Education for the X-ray
diffractometer and a grant from the Geneseo Foundation.
Walker, M., Harvey, A. J. A., Sen, A. & Dessent, C. E. H. (2013). J.
Phys. Chem. A, 117, 12590–12600.
Wavefunction. (2016). SPARTAN’16. Wavefunction Inc., Irvine, CA,
USA.
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.
References
˙
Zesławska, E., Nitek, W. & Handzlik, J. (2017). Acta Cryst. C73, 1151–
1157.
Allen, F. H., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R.
(2004). International Tables for Crystallography, 3rd ed., edited by
E. Prince, pp. 790–811. Heidelberg: Springer Verlag.
Zhao, Y. & Truhlar, D. G. (2008). Theor. Chem. Acc. 120, 215–241.
Zick, P. L. & Geiger, D. K. (2018). Acta Cryst. C74, 1725–1731.
ꢂ
Acta Cryst. (2019). C75
Powers and Geiger
Hydrogen bonding in benzene-1,2-diamine salts and cocrystal 7 of 7

supporting information
supporting information
Acta Cryst. (2019). C75 [https://doi.org/10.1107/S2053229619002262]
Hydrogen bonding in two benzene-1,2-diaminium pyridine-2-carboxylate salts
and a cocrystal of benzene-1,2-diamine and benzoic acid
Kyle A. Powers and David K. Geiger
Computing details
For all structures, data collection: APEX2 (Bruker, 2015); cell refinement: APEX2 (Bruker, 2015); data reduction: SAINT
(Bruker, 2015); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure:
SHELXL2014 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software
used to prepare material for publication: publCIF (Westrip, 2010).
Benzene-1,2-diaminium bis(pyridine-2-carboxylate) (1)
Crystal data
0.5C6H10N22+·C6H4NO2−
Mr = 177.18
F(000) = 744
Dx = 1.365 Mg m−3
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 2197 reflections
θ = 2.3–23.1°
Monoclinic, C2/c
a = 21.467 (5) Å
b = 7.675 (2) Å
c = 12.837 (3) Å
β = 125.362 (7)°
V = 1724.8 (7) Å3
Z = 8
µ = 0.10 mm−1
T = 200 K
Prism, clear brown
0.50 × 0.30 × 0.25 mm
Data collection
Bruker SMART X2S benchtop
diffractometer
Radiation source: XOS X-beam microfocus
source
Doubly curved silicon crystal monochromator
Detector resolution: 8.3330 pixels mm-1
ω scans
Absorption correction: multi-scan
(SADABS; Bruker, 2015)
Tmin = 0.61, Tmax = 0.98
8287 measured reflections
1573 independent reflections
1161 reflections with I > 2σ(I)
Rint = 0.063
θ
max = 25.4°, θmin = 2.3°
h = −25→25
k = −9→6
l = −15→14
Refinement
Refinement on F2
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.047
wR(F2) = 0.138
S = 1.04
Hydrogen site location: mixed
H atoms treated by a mixture of independent
and constrained refinement
w = 1/[σ2(Fo2) + (0.0685P)2 + 0.2917P]
where P = (Fo2 + 2Fc2)/3
1573 reflections
130 parameters
3 restraints
(Δ/σ)max < 0.001
Δρmax = 0.20 e Å−3
Δρmin = −0.26 e Å−3
Acta Cryst. (2019). C75
sup-1

supporting information
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance
matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles;
correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate
(isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
x
y
z
Uiso*/Ueq
N1
H1A
H1B
H1C
C1
C2
H2
C3
H3
O1
O2
C4
N2
C5
C6
H6
C7
0.45266 (9)
0.4185 (11)
0.4267 (11)
0.4938 (12)
0.47781 (9)
0.45715 (11)
0.4278
0.5387 (2)
0.559 (3)
0.464 (2)
0.470 (3)
0.7015 (2)
0.8578 (2)
0.8585
0.61312 (15)
0.5265 (15)
0.6356 (19)
0.624 (2)
0.68382 (16)
0.6183 (2)
0.5277
0.0373 (4)
0.058 (6)*
0.058 (6)*
0.082 (7)*
0.0348 (4)
0.0494 (5)
0.059*
0.47923 (14)
0.4654
1.0128 (3)
1.1202
0.6850 (2)
0.6401
0.0671 (6)
0.081*
0.57010 (7)
0.64209 (8)
0.63292 (11)
0.69229 (9)
0.70385 (10)
0.77514 (11)
0.7817
0.83688 (11)
0.8866
0.82608 (12)
0.8681
0.38679 (19)
0.36981 (19)
0.3725 (2)
0.3856 (2)
0.3601 (2)
0.3280 (3)
0.31
0.3225 (3)
0.2985
0.3519 (3)
0.3509
0.63284 (13)
0.84518 (13)
0.73992 (18)
0.62789 (14)
0.74123 (16)
0.85123 (18)
0.9303
0.8442 (2)
0.9183
0.7301 (2)
0.7239
0.0546 (4)
0.0583 (5)
0.0416 (5)
0.0456 (4)
0.0370 (4)
0.0501 (5)
0.06*
0.0614 (6)
0.074*
0.0601 (6)
0.072*
H7
C8
H8
C9
0.75375 (12)
0.7466
0.3828 (3)
0.4034
0.6250 (2)
0.5458
0.0560 (6)
0.067*
H9
Atomic displacement parameters (Å2)
U11
U22
U33
U12
U13
U23
N1
C1
C2
C3
O1
O2
C4
N2
C5
C6
C7
C8
C9
0.0343 (8)
0.0282 (8)
0.0485 (11)
0.0789 (15)
0.0353 (7)
0.0554 (9)
0.0426 (11)
0.0367 (8)
0.0363 (10)
0.0428 (11)
0.0350 (11)
0.0404 (11)
0.0497 (12)
0.0485 (9)
0.0300 (9)
0.0001 (6)
−0.0011 (7)
0.0013 (9)
0.0022 (11)
0.0081 (6)
0.0184 (7)
0.0071 (8)
0.0045 (7)
0.0045 (7)
0.0098 (9)
0.0127 (10)
0.0054 (10)
0.0058 (10)
0.0191 (7)
0.0204 (7)
0.0212 (10)
0.0259 (12)
0.0228 (7)
0.0362 (8)
0.0268 (10)
0.0227 (8)
0.0206 (9)
0.0204 (9)
0.0178 (10)
0.0349 (11)
0.0361 (11)
−0.0001 (7)
−0.0006 (7)
0.0054 (9)
0.0083 (10)
−0.0003 (7)
0.0113 (7)
0.0030 (8)
0.0015 (7)
−0.0001 (7)
0.0009 (9)
−0.0041 (11)
−0.0058 (11)
0.0015 (11)
0.0462 (10)
0.0541 (12)
0.0464 (12)
0.0875 (11)
0.0876 (11)
0.0479 (10)
0.0653 (11)
0.0433 (10)
0.0667 (13)
0.0840 (16)
0.0846 (16)
0.0811 (15)
0.0342 (9)
0.0388 (12)
0.0541 (13)
0.0418 (9)
0.0445 (9)
0.0395 (12)
0.0371 (10)
0.0326 (11)
0.0366 (11)
0.0522 (14)
0.0636 (15)
0.0500 (13)
Acta Cryst. (2019). C75
sup-2

supporting information
Geometric parameters (Å, º)
N1—C1
N1—H1A
N1—H1B
N1—H1C
C1—C2
C1—C1i
C2—C3
C2—H2
C3—C3i
C3—H3
O1—C4
O2—C4
1.453 (2)
0.925 (16)
0.955 (15)
0.969 (16)
1.382 (2)
1.386 (3)
1.380 (3)
0.95
1.362 (5)
0.95
1.255 (2)
1.248 (2)
C4—C5
N2—C9
N2—C5
C5—C6
C6—C7
C6—H6
C7—C8
C7—H7
C8—C9
C8—H8
C9—H9
1.516 (2)
1.341 (2)
1.341 (2)
1.377 (3)
1.381 (3)
0.95
1.362 (3)
0.95
1.365 (3)
0.95
0.95
C1—N1—H1A
C1—N1—H1B
H1A—N1—H1B
C1—N1—H1C
H1A—N1—H1C
H1B—N1—H1C
C2—C1—C1i
C2—C1—N1
C1i—C1—N1
C3—C2—C1
C3—C2—H2
C1—C2—H2
C3i—C3—C2
C3i—C3—H3
C2—C3—H3
O2—C4—O1
O2—C4—C5
111.0 (14)
113.7 (12)
105.6 (18)
113.7 (15)
106.5 (18)
105.9 (19)
119.77 (11)
119.62 (16)
120.61 (9)
119.8 (2)
120.1
120.1
120.42 (12)
119.8
119.8
125.73 (16)
117.31 (17)
O1—C4—C5
C9—N2—C5
N2—C5—C6
N2—C5—C4
C6—C5—C4
C5—C6—C7
C5—C6—H6
C7—C6—H6
C8—C7—C6
C8—C7—H7
C6—C7—H7
C7—C8—C9
C7—C8—H8
C9—C8—H8
N2—C9—C8
N2—C9—H9
C8—C9—H9
116.96 (15)
117.39 (17)
122.46 (16)
115.13 (16)
122.40 (16)
118.53 (18)
120.7
120.7
119.54 (19)
120.2
120.2
118.68 (18)
120.7
120.7
123.38 (19)
118.3
118.3
C1i—C1—C2—C3
N1—C1—C2—C3
C1—C2—C3—C3i
C9—N2—C5—C6
C9—N2—C5—C4
O2—C4—C5—N2
O1—C4—C5—N2
O2—C4—C5—C6
−1.6 (3)
178.30 (17)
−0.5 (4)
O1—C4—C5—C6
N2—C5—C6—C7
C4—C5—C6—C7
C5—C6—C7—C8
C6—C7—C8—C9
C5—N2—C9—C8
C7—C8—C9—N2
−173.88 (18)
0.2 (3)
−178.61 (18)
1.2 (3)
−1.2 (3)
1.5 (3)
−1.5 (3)
177.41 (16)
−171.91 (16)
7.2 (2)
−0.1 (4)
7.0 (3)
Symmetry code: (i) −x+1, y, −z+3/2.
Hydrogen-bond geometry (Å, º)
Cg(bdaH22+) refers to the ring centroid of the benzene-1,2-diaminium cation.
D—H···A
D—H
H···A
D···A
D—H···A
N1—H1A···O1ii
0.93 (2)
2.24 (2)
2.958 (2)
135 (2)
Acta Cryst. (2019). C75
sup-3

supporting information
N1—H1A···N2ii
N1—H1B···O2i
N1—H1C···O1
C8—H8···Cg(bdaH22+
0.93 (2)
0.96 (2)
0.97 (2)
0.95
2.08 (2)
1.78 (2)
1.70 (2)
2.65
2.907 (2)
149 (2)
164 (2)
168 (2)
170
2.7137 (19)
2.6533 (19)
3.592 (3)
iii
)
Symmetry codes: (i) −x+1, y, −z+3/2; (ii) −x+1, −y+1, −z+1; (iii) x+1/2, y−1/2, z.
4,5-Dimethylbenzene-1,2-diaminium bis(pyridine-2-carboxylate) (2)
Crystal data
0.5C8H14N22+·C6H4NO2−
Mr = 191.21
F(000) = 808
Dx = 1.252 Mg m−3
Monoclinic, C2/c
a = 21.451 (4) Å
b = 9.0100 (19) Å
c = 12.585 (3) Å
β = 123.447 (6)°
V = 2029.5 (7) Å3
Z = 8
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 2093 reflections
θ = 2.5–23.6°
µ = 0.09 mm−1
T = 200 K
Block, clear colourless
0.60 × 0.50 × 0.25 mm
Data collection
Bruker SMART X2S benchtop
diffractometer
Radiation source: XOS X-beam microfocus
source
Doubly curved silicon crystal monochromator
Detector resolution: 8.3330 pixels mm-1
ω scans
Absorption correction: multi-scan
(SADABS; Bruker, 2015)
Tmin = 0.61, Tmax = 0.98
7764 measured reflections
1794 independent reflections
1201 reflections with I > 2σ(I)
Rint = 0.080
θ
max = 25.4°, θmin = 2.5°
h = −25→25
k = −10→10
l = −15→14
Refinement
Refinement on F2
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.044
wR(F2) = 0.128
S = 1.01
1794 reflections
140 parameters
3 restraints
Primary atom site location: structure-invariant
direct methods
Secondary atom site location: difference Fourier
map
Hydrogen site location: mixed
H atoms treated by a mixture of independent
and constrained refinement
w = 1/[σ2(Fo2) + (0.0512P)2]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max < 0.001
Δρmax = 0.14 e Å−3
Δρmin = −0.19 e Å−3
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance
matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles;
correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate
(isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.
Acta Cryst. (2019). C75
sup-4

supporting information
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
x
y
z
Uiso*/Ueq
O1
O2
N1
N2
H2A
H2B
H2C
C1
C2
C3
0.42726 (7)
0.35918 (7)
0.30655 (9)
0.54686 (9)
0.5757 (10)
0.5048 (9)
0.5774 (9)
0.36696 (10)
0.30035 (9)
0.23710 (10)
0.2342
0.91055 (15)
0.87343 (16)
0.89341 (16)
0.02590 (15)
−0.034 (2)
−0.028 (2)
0.046 (2)
0.87944 (17)
0.84935 (18)
0.7799 (2)
0.7504
0.36543 (11)
0.15592 (11)
0.37525 (13)
0.38711 (13)
0.3665 (19)
0.3788 (17)
0.4716 (14)
0.26126 (16)
0.26854 (14)
0.16953 (16)
0.0945
0.0570 (4)
0.0620 (4)
0.0501 (4)
0.0381 (4)
0.071 (6)*
0.066 (6)*
0.058 (6)*
0.0428 (5)
0.0397 (4)
0.0523 (5)
0.063*
H3
C4
H4
0.17839 (10)
0.1348
0.7550 (2)
0.7046
0.18321 (19)
0.1186
0.0625 (6)
0.075*
C5
H5
0.18355 (11)
0.1431
0.8033 (2)
0.7897
0.29038 (19)
0.3003
0.0662 (6)
0.079*
C6
H6
0.24789 (12)
0.2509
0.8718 (2)
0.9054
0.38375 (19)
0.458
0.0620 (6)
0.074*
C7
C8
H8
0.52181 (8)
0.54091 (9)
0.5689
0.16447 (17)
0.29813 (18)
0.2977
0.31600 (14)
0.38044 (15)
0.4709
0.0351 (4)
0.0438 (5)
0.053*
C9
0.52030 (10)
0.54175 (15)
0.5755
0.567
0.4967
0.4332 (2)
0.5765 (2)
0.6329
0.5543
0.6351
0.31640 (17)
0.3908 (2)
0.3764
0.4817
0.3624
0.0520 (5)
0.0838 (8)
0.126*
0.126*
0.126*
C10
H10A
H10B
H10C
Atomic displacement parameters (Å2)
U11
U22
U33
U12
U13
U23
O1
O2
N1
N2
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
0.0424 (8)
0.0674 (9)
0.0465 (10)
0.0395 (9)
0.0464 (12)
0.0401 (11)
0.0509 (12)
0.0429 (13)
0.0474 (14)
0.0559 (13)
0.0320 (10)
0.0445 (11)
0.0557 (12)
0.117 (2)
0.0826 (10)
0.0805 (10)
0.0648 (10)
0.0422 (8)
0.0418 (9)
0.0426 (9)
0.0557 (11)
0.0680 (13)
0.0874 (17)
0.0867 (15)
0.0399 (9)
0.0479 (10)
0.0432 (10)
0.0473 (12)
0.0510 (8)
−0.0109 (6)
−0.0222 (7)
−0.0058 (7)
0.0010 (6)
−0.0046 (8)
−0.0013 (7)
−0.0101 (9)
−0.0153 (9)
−0.0065 (11)
−0.0032 (11)
0.0003 (6)
0.0289 (7)
0.0462 (7)
0.0312 (7)
0.0233 (7)
0.0296 (9)
0.0247 (8)
0.0279 (9)
0.0246 (10)
0.0435 (12)
0.0419 (11)
0.0250 (7)
0.0278 (8)
0.0394 (10)
0.0600 (15)
0.0005 (6)
0.0570 (8)
0.0475 (9)
0.0363 (8)
0.0466 (10)
0.0405 (9)
0.0504 (11)
0.0675 (14)
0.0781 (15)
0.0595 (12)
0.0411 (8)
0.0443 (10)
0.0662 (11)
0.0915 (16)
−0.0156 (6)
−0.0022 (7)
0.0011 (5)
−0.0018 (7)
0.0027 (6)
−0.0037 (8)
0.0040 (10)
0.0096 (11)
−0.0009 (10)
−0.0001 (6)
−0.0043 (6)
−0.0066 (7)
−0.0141 (9)
−0.0048 (8)
−0.0033 (8)
−0.0099 (12)
Acta Cryst. (2019). C75
sup-5

supporting information
Geometric parameters (Å, º)
O1—C1
O2—C1
N1—C6
N1—C2
N2—C7
N2—H2A
N2—H2B
N2—H2C
C1—C2
C2—C3
C3—C4
C3—H3
C4—C5
1.265 (2)
1.243 (2)
1.334 (2)
1.335 (2)
1.455 (2)
0.959 (16)
0.979 (15)
0.908 (14)
1.506 (3)
1.386 (2)
1.380 (3)
0.95
C4—H4
C5—C6
C5—H5
C6—H6
C7—C8
C7—C7i
C8—C9
C8—H8
C9—C9i
C9—C10
C10—H10A
C10—H10B
C10—H10C
0.95
1.371 (3)
0.95
0.95
1.382 (2)
1.386 (3)
1.390 (2)
0.95
1.395 (4)
1.510 (2)
0.98
0.98
0.98
1.363 (3)
C6—N1—C2
C7—N2—H2A
C7—N2—H2B
H2A—N2—H2B
C7—N2—H2C
H2A—N2—H2C
H2B—N2—H2C
O2—C1—O1
O2—C1—C2
O1—C1—C2
N1—C2—C3
N1—C2—C1
C3—C2—C1
C4—C3—C2
C4—C3—H3
C2—C3—H3
C5—C4—C3
C5—C4—H4
C3—C4—H4
C4—C5—C6
117.50 (16)
113.1 (13)
110.8 (11)
112.6 (17)
109.7 (11)
105.7 (16)
104.5 (17)
125.06 (17)
118.88 (15)
116.05 (15)
122.95 (17)
115.85 (14)
121.20 (16)
118.02 (18)
121.0
C4—C5—H5
C6—C5—H5
N1—C6—C5
N1—C6—H6
C5—C6—H6
C8—C7—C7i
C8—C7—N2
C7i—C7—N2
C7—C8—C9
C7—C8—H8
C9—C8—H8
C8—C9—C9i
C8—C9—C10
C9i—C9—C10
C9—C10—H10A
C9—C10—H10B
H10A—C10—H10B
C9—C10—H10C
H10A—C10—H10C
H10B—C10—H10C
120.4
120.4
123.06 (19)
118.5
118.5
119.29 (9)
119.81 (14)
120.89 (8)
121.73 (16)
119.1
119.1
118.90 (10)
119.88 (18)
121.22 (12)
109.5
109.5
109.5
109.5
109.5
109.5
121.0
119.31 (18)
120.3
120.3
119.1 (2)
C6—N1—C2—C3
C6—N1—C2—C1
O2—C1—C2—N1
O1—C1—C2—N1
O2—C1—C2—C3
O1—C1—C2—C3
N1—C2—C3—C4
C1—C2—C3—C4
−1.6 (3)
C2—C3—C4—C5
C3—C4—C5—C6
C2—N1—C6—C5
C4—C5—C6—N1
C7i—C7—C8—C9
N2—C7—C8—C9
C7—C8—C9—C9i
C7—C8—C9—C10
2.2 (3)
−1.9 (3)
2.0 (3)
−0.2 (3)
−2.9 (3)
177.82 (16)
−0.4 (3)
179.38 (18)
178.42 (15)
−163.60 (16)
15.8 (2)
16.5 (3)
−164.09 (16)
−0.4 (3)
179.53 (16)
Symmetry code: (i) −x+1, y, −z+1/2.
Acta Cryst. (2019). C75
sup-6

supporting information
Hydrogen-bond geometry (Å, º)
Cg(Me2bdaH22+) refers to the ring centroid of the 4,5-dimethyl-benzene-1,2-diaminium cation.
D—H···A
D—H
H···A
D···A
D—H···A
N2—H2A···O2ii
0.96 (2)
0.98 (2)
0.91 (1)
0.91 (1)
0.95
1.78 (2)
1.67 (2)
2.14 (2)
2.22 (2)
2.77
2.729 (2)
2.639 (2)
2.9032 (19)
2.999 (2)
3.682 (3)
171 (2)
169 (2)
141 (2)
144 (2)
160
N2—H2B···O1iii
N2—H2C···O1iv
N2—H2C···N1iv
C5—H5···Cg(Me2bdaH22+
v
)
Symmetry codes: (ii) −x+1, y−1, −z+1/2; (iii) x, y−1, z; (iv) −x+1, −y+1, −z+1; (v) x−1/2, y+1/2, z.
Benzene-1,2-diamine bis(benzoic acid) (3)
Crystal data
0.5C6H8N2·C7H6O2
Mr = 176.19
Dx = 1.272 Mg m−3
Mo Kα radiation, λ = 0.71073 Å
Cell parameters from 4994 reflections
θ = 2.8–24.2°
µ = 0.09 mm−1
T = 200 K
Plate, clear colourless
0.60 × 0.48 × 0.20 mm
Orthorhombic, Pbcn
a = 20.061 (3) Å
b = 7.8464 (10) Å
c = 11.6895 (12) Å
V = 1840.0 (4) Å3
Z = 8
F(000) = 744
Data collection
Bruker SMART X2S benchtop
diffractometer
Radiation source: XOS X-beam microfocus
source
Doubly curved silicon crystal monochromator
Detector resolution: 8.3330 pixels mm-1
ω scans
Absorption correction: multi-scan
(SADABS; Bruker, 2015)
Tmin = 0.64, Tmax = 0.98
30170 measured reflections
1638 independent reflections
1337 reflections with I > 2σ(I)
Rint = 0.064
θ
max = 25.2°, θmin = 2.8°
h = −23→23
k = −9→9
l = −13→13
Refinement
Refinement on F2
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.030
wR(F2) = 0.087
H atoms treated by a mixture of independent
and constrained refinement
w = 1/[σ2(Fo2) + (0.0426P)2 + 0.2144P]
where P = (Fo2 + 2Fc2)/3
S = 1.05
1638 reflections
131 parameters
(Δ/σ)max < 0.001
Δρmax = 0.12 e Å−3
Δρmin = −0.12 e Å−3
0 restraints
Hydrogen site location: mixed
Extinction correction: SHELXL2014
(Sheldrick, 2015)
Extinction coefficient: 0.036 (2)
Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance
matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles;
correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate
(isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Acta Cryst. (2019). C75
sup-7

supporting information
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
x
y
z
Uiso*/Ueq
O1
H1C
O2
N1
H1A
H1B
C1
H1
C2
H2
C3
H3
C4
C5
C6
H6
C7
0.35377 (4)
0.3984 (9)
0.40648 (4)
0.46617 (5)
0.4497 (7)
0.5014 (8)
0.16309 (8)
0.1204
0.21951 (8)
0.2156
0.28164 (7)
0.3205
0.28756 (6)
0.35476 (6)
0.16825 (7)
0.1292
0.23038 (6)
0.234
0.48442 (7)
0.4736
0.46876 (6)
0.4472
0.51824 (13)
0.489 (2)
0.24544 (7)
0.2143 (15)
0.40443 (7)
0.14608 (9)
0.0737 (13)
0.1440 (12)
0.48889 (14)
0.5196
0.55063 (13)
0.6244
0.50592 (11)
0.5488
0.39861 (10)
0.35138 (10)
0.38286 (14)
0.341
0.33734 (12)
0.2639
0.19776 (14)
0.1616
0.14506 (11)
0.0727
0.0577 (3)
0.094 (5)*
0.0566 (3)
0.0445 (3)
0.061 (4)*
0.060 (4)*
0.0698 (4)
0.084*
0.0661 (4)
0.079*
0.0537 (4)
0.064*
0.0421 (3)
0.0425 (3)
0.0668 (4)
0.08*
0.0534 (3)
0.064*
0.0703 (4)
0.084*
0.0544 (4)
0.065*
0.59582 (12)
0.40589 (14)
0.3912 (16)
0.4803 (19)
0.6783 (2)
0.7037
0.71645 (18)
0.7662
0.68275 (16)
0.7097
0.60956 (14)
0.57469 (14)
0.6037 (2)
0.5757
0.56947 (16)
0.5184
−0.05934 (19)
−0.1642
0.09306 (17)
0.0922
H7
C8
H8
C9
H9
C10
0.48419 (5)
0.24690 (15)
0.19649 (10)
0.0403 (3)
Atomic displacement parameters (Å2)
U11
U22
U33
U12
U13
U23
O1
O2
N1
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
0.0473 (5)
0.0435 (5)
0.0400 (6)
0.0568 (9)
0.0750 (10)
0.0589 (8)
0.0444 (7)
0.0456 (7)
0.0423 (7)
0.0472 (7)
0.0651 (9)
0.0448 (7)
0.0288 (5)
0.0887 (7)
0.0792 (6)
0.0623 (7)
0.0712 (9)
0.0680 (9)
0.0570 (7)
0.0431 (6)
0.0470 (6)
0.0789 (10)
0.0624 (8)
0.0578 (8)
0.0673 (8)
0.0570 (7)
0.0370 (5)
0.0470 (5)
0.0311 (6)
0.0815 (11)
0.0552 (9)
0.0452 (7)
0.0387 (6)
0.0350 (6)
0.0793 (11)
0.0505 (8)
0.0879 (11)
0.0512 (8)
0.0352 (6)
0.0157 (5)
0.0051 (4)
−0.0011 (5)
0.0126 (7)
0.0142 (7)
0.0086 (6)
0.0053 (5)
0.0056 (5)
−0.0010 (7)
0.0002 (6)
−0.0009 (7)
0.0002 (6)
0.0012 (5)
−0.0043 (4)
−0.0086 (4)
−0.0041 (4)
0.0262 (8)
0.0189 (7)
0.0016 (6)
−0.0001 (5)
−0.0049 (5)
0.0007 (7)
−0.0025 (6)
−0.0181 (8)
−0.0078 (6)
0.0019 (4)
−0.0083 (4)
−0.0077 (4)
0.0016 (4)
0.0159 (8)
0.0008 (7)
−0.0003 (6)
0.0060 (5)
0.0033 (5)
0.0119 (8)
0.0028 (6)
−0.0114 (7)
−0.0111 (6)
−0.0005 (5)
Geometric parameters (Å, º)
O1—C5
O1—H1C
1.3153 (14)
0.994 (19)
C3—H3
C4—C7
0.95
1.3885 (17)
Acta Cryst. (2019). C75
sup-8

supporting information
O2—C5
N1—C10
N1—H1A
N1—H1B
C1—C6
C1—C2
C1—H1
C2—C3
C2—H2
C3—C4
1.2201 (14)
1.4262 (15)
0.916 (15)
0.916 (16)
1.375 (2)
1.375 (2)
0.95
1.3771 (19)
0.95
1.3848 (17)
C4—C5
C6—C7
C6—H6
C7—H7
C8—C8i
C8—C9
C8—H8
C9—C10
C9—H9
C10—C10i
1.4822 (16)
1.3816 (19)
0.95
0.95
1.372 (3)
1.3814 (19)
0.95
1.3836 (17)
0.95
1.403 (2)
C5—O1—H1C
C10—N1—H1A
C10—N1—H1B
H1A—N1—H1B
C6—C1—C2
C6—C1—H1
C2—C1—H1
C1—C2—C3
C1—C2—H2
C3—C2—H2
C2—C3—C4
C2—C3—H3
C4—C3—H3
C3—C4—C7
C3—C4—C5
C7—C4—C5
O2—C5—O1
114.1 (10)
111.3 (8)
111.9 (9)
109.5 (12)
120.25 (13)
119.9
119.9
120.26 (13)
119.9
O2—C5—C4
O1—C5—C4
C1—C6—C7
C1—C6—H6
C7—C6—H6
C6—C7—C4
C6—C7—H7
C4—C7—H7
C8i—C8—C9
C8i—C8—H8
C9—C8—H8
C8—C9—C10
C8—C9—H9
C10—C9—H9
C9—C10—C10i
C9—C10—N1
C10i—C10—N1
123.99 (11)
113.52 (10)
119.87 (14)
120.1
120.1
120.17 (13)
119.9
119.9
120.04 (8)
120.0
120.0
120.69 (12)
119.7
119.9
120.07 (13)
120.0
120.0
119.36 (11)
119.48 (11)
121.16 (11)
122.49 (11)
119.7
119.26 (7)
121.79 (11)
118.89 (6)
C6—C1—C2—C3
C1—C2—C3—C4
C2—C3—C4—C7
C2—C3—C4—C5
C3—C4—C5—O2
C7—C4—C5—O2
C3—C4—C5—O1
C7—C4—C5—O1
1.1 (2)
−0.3 (2)
C2—C1—C6—C7
C1—C6—C7—C4
C3—C4—C7—C6
C5—C4—C7—C6
C8i—C8—C9—C10
C8—C9—C10—C10i
C8—C9—C10—N1
−1.1 (2)
0.3 (2)
0.52 (19)
−179.75 (11)
0.0 (3)
−0.53 (19)
179.74 (11)
5.18 (18)
−174.54 (11)
−174.73 (11)
5.54 (16)
−0.3 (2)
−177.43 (12)
Symmetry code: (i) −x+1, y, −z+1/2.
Hydrogen-bond geometry (Å, º)
Cg(bda) refers to the ring centroid of the benzene-1,2-diamine.
D—H···A
D—H
H···A
D···A
D—H···A
O1—H1C···N1
N1—H1A···O2ii
0.994 (19)
0.916 (15)
1.706 (19)
2.163 (16)
2.6852 (13)
3.0681 (14)
167.8 (16)
169.8 (12)
Acta Cryst. (2019). C75
sup-9

supporting information
N1—H1B···O2i
C6—H6···Cg(bda)iii
0.916 (16)
0.95
2.136 (16)
2.81
3.0160 (14)
3.7163 (16)
160.8 (12)
161
Symmetry codes: (i) −x+1, y, −z+1/2; (ii) x, −y+1, z−1/2; (iii) x−1/2, y+1/2, −z+1/2.
Acta Cryst. (2019). C75
sup-10