Low-dimensional hydrogen-bonded structures in the 1:1 and 1:2 proton-transfer compounds of 4,5-dichloro-phthalic acid with the aliphatic Lewis bases triethyl-amine, diethyl-amine, n-butyl-amine and piperidine

Article abstract of DOI:10.1107/S0108270110022328

The structures of the proton-transfer compounds of 4,5-di-chloro-phthalic acid (DCPA) with the aliphatic Lewis bases triethyl-amine, diethyl-amine, n-butyl-amine and piperidine, namely triethyl-aminium 2-carb-oxy-4,5-dichloro- benzoate, C₆H₁₆N⁺·C₈H ₃Cl₂O₄ ^-, (I), diethyl-aminium 2-carb-oxy-4,5-dichloro-benzoate, C₄H₁₂N ⁺·C₈H₃Cl₂O₄ ^-, (II), bis-(butan-aminium) 4,5-dichloro-benzene-1,2-dicarboxylate monohydrate, 2C₄H₁₂N⁺·C ₈H₂Cl₂O₄^2-·H ₂O, (III), and bis(piperidinium) 4,5-dichloro-benzene-1,2- dicarboxylate monohydrate, 2C₅H₁₂N⁺· C₈H₂Cl₂O₄^2-·H ₂O, (IV), have been determined at 200 K. All compounds have hydrogen-bonding associations, giving discrete cation-anion units in (I) and linear chains in (II), while (III) and (IV) both have two-dimensional structures. In (I), a discrete cation-anion unit is formed through an asymmetric R₁²(4) N⁺ - H...O₂ hydrogen-bonding association, whereas in (II), chains are formed through linear N - H...O associations involving both aminium H-atom donors. In compounds (III) and (IV), the primary N - H...O-linked cation-anion units are extended into a two-dimensional sheet structure via amide-carboxyl N - H...O and amide-carbonyl N - H...O inter-actions. In the 1:1 salts (I) and (II), the hydrogen 4,5-dichloro-phthalate anions are essentially planar with short intra-molecular carbox-yl-carboxyl O - H...O hydrogen bonds [O...O = 2.4223 (14) and 2.388 (2) A, respectively]. This work provides a further example of the uncommon zero-dimensional hydrogen-bonded DCPA-Lewis base salt and the one-dimensional chain structure type, while even with the hydrate structures of the 1:2 salts with the primary and secondary amines, the low dimensionality generally associated with 1:1 DCPA salts is also found.

Full text of DOI:10.1107/S0108270110022328

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
Comment
The proton-transfer compounds of the acid salts of 4,5-di-
chlorophthalic acid (DCPA) with aromatic and hetero-
aromatic nitrogen Lewis bases generally show low-
dimensional hydrogen-bonded structure types (Smith et al.,
2008a, 2009a), with the occurrence of three-dimensional
structures limited to the salts with the bifunctional associative-
group-substituted compounds 3- and 4-aminobenzoic acid
(Smith et al., 2008b) and 4-chloroaniline (Smith et al., 2009b).
In two of these examples (with the aminocarboxylic acids), the
primary hydrogen-bonded cation–anion ‘heterodimers’ (Etter
& Adsmond, 1990) are extended into sheet substructures then
into three-dimensional framework structures through cation
associative-substituent-group interactions. In these three-
dimensional structures, the DCPA anions are nonplanar (the
‘nonplanar’ conformation), whereas in the low-dimensional
structure types the DCPA anion species are essentially planar
(the ‘planar’ conformation) with the planarity a consequence
of the short intramolecular carboxyl–carboxyl O—Hꢀ ꢀ ꢀO
ISSN 0108-2701
Low-dimensional hydrogen-bonded
structures in the 1:1 and 1:2 proton-
transfer compounds of 4,5-dichloro-
phthalic acid with the aliphatic Lewis
bases triethylamine, diethylamine,
n-butylamine and piperidine
Graham Smitha* and Urs D. Wermuthb
aFaculty of Science and Technology, Queensland University of Technology, GPO
Box 2434, Brisbane, Queensland 4001, Australia, and bSchool of Biomolecular and
Physical Sciences, Griffith University, Nathan, Queensland 4111, Australia
Correspondence e-mail: g.smith@qut.edu.au
˚
hydrogen bond [typically 2.4054 (19) A in the 1:1 1,10-
phenanthroline–DCPA salt (Smith et al., 2009c)].
Received 20 May 2010
Accepted 10 June 2010
Online 23 June 2010
The structures of the proton-transfer compounds of 4,5-
dichlorophthalic acid (DCPA) with the aliphatic Lewis bases
triethylamine, diethylamine, n-butylamine and piperidine,
namely triethylaminium 2-carboxy-4,5-dichlorobenzoate,
C6H16N+ꢀC8H3Cl2O4ꢁ, (I), diethylaminium 2-carboxy-4,5-di-
chlorobenzoate, C4H12N+ꢀC8H3Cl2O4ꢁ, (II), bis(butanamin-
ium) 4,5-dichlorobenzene-1,2-dicarboxylate monohydrate,
2C4H12N+ꢀC8H2Cl2O42ꢁꢀH2O, (III), and bis(piperidinium) 4,5-
dichlorobenzene-1,2-dicarboxylate monohydrate, 2C5H12N+ꢀ-
C8H2Cl2O42ꢁꢀH2O, (IV), have been determined at 200 K. All
compounds have hydrogen-bonding associations, giving
discrete cation–anion units in (I) and linear chains in (II),
while (III) and (IV) both have two-dimensional structures. In
(I), a discrete cation–anion unit is formed through an
asymmetric R21(4) N+—Hꢀ ꢀ ꢀO2 hydrogen-bonding association,
whereas in (II), chains are formed through linear N—Hꢀ ꢀ ꢀO
associations involving both aminium H-atom donors. In
compounds (III) and (IV), the primary N—Hꢀ ꢀ ꢀO-linked
cation–anion units are extended into a two-dimensional sheet
structure via amide–carboxyl N—Hꢀ ꢀ ꢀO and amide–carbonyl
N—Hꢀ ꢀ ꢀO interactions. In the 1:1 salts (I) and (II), the
hydrogen 4,5-dichlorophthalate anions are essentially planar
with short intramolecular carboxyl–carboxyl O—Hꢀ ꢀ ꢀO
The 1:1 examples with the secondary aliphatic amine
diisopropylamine and the tertiary amine hexamethylene-
tetramine (Smith & Wermuth, 2010a) show simple one-
dimensional hydrogen-bonded chain structures. Hydrates are
also uncommon among the structures of the 1:1 proton-
transfer compounds of DCPA, which is unusual considering
that their common preparation is in aqueous alcoholic solu-
tion, or they are recrystallized from water, as is the case with
the four compounds reported here. The only five known
hydrated examples are the ammonium salt (Mattes & Dorau,
1986) (a monohydrate) and the salts with quinaldic acid (a
monohydrate; Smith et al., 2008a), 2-aminobenzoic acid (a
dihydrate; Smith et al., 2008b), hexamethylenetetramine (a
monohydrate; Smith & Wermuth, 2010a) and the salt of the
˚
hydrogen bonds [Oꢀ ꢀ ꢀO = 2.4223 (14) and 2.388 (2) A,
respectively]. This work provides a further example of the
uncommon zero-dimensional hydrogen-bonded DCPA–Lewis
base salt and the one-dimensional chain structure type,
while even with the hydrate structures of the 1:2 salts with
the primary and secondary amines, the low dimen-
sionality generally associated with 1:1 DCPA salts is also
found.
o374 # 2010 International Union of Crystallography
doi:10.1107/S0108270110022328
Acta Cryst. (2010). C66, o374–o380

organic compounds
Figure 1
Figure 3
The molecular configuration and atom-numbering scheme for the
triethylaminium cation and the 2-carboxy-4,5-dichlorobenzoate anion in
(I). Non-H atoms are shown as 40% probability displacement ellipsoids.
The molecular configuration and atom-numbering scheme for the two
n-butylaminium cations (A and B), the 4,5-dichlorophthalate dianion and
the water molecule of solvation (O1W) in (III). Inter- and intra-species
hydrogen bonds are shown as dashed lines and non-H atoms are shown as
40% probability displacement ellipsoids.
Figure 2
The molecular configuration and atom-numbering scheme for the
isopropylaminium cation and the 2-carboxy-4,5-dichlorobenzoate anion
in (II). Non-H atoms are shown as 40% probability displacement
ellipsoids.
Figure 4
The molecular configuration and atom-numbering scheme for the two
piperidinium cations (A and B), the 4,5-dichlorophthalate dianion and
the water molecule of solvation (O1W) in (IV). Non-H atoms are shown
as 40% probability displacement ellipsoids.
drug quinacrine (a tetrahydrate; Smith et al., 2009). The
dianionic DCPA anion is similarly uncommon among the
known structures, examples being the salts with 4-ethylaniline
˘
¨ ¨
¨
¨
(Odabas¸oglu & Buyukgungor, 2007) and ethylenediamine
(Smith & Wermuth, 2010c). It has been previously noted
(Smith et al., 2009c) in the structure of the 1,10-phenan-
throlinium salt that with the ‘planar’ DCPA cations, there is a
common set of abnormal bond parameters associated with the
intramolecular hydrogen-bonded unit which typically evoke
level C alerts in checkCIF (Spek, 2009), viz. significant bond
lengthening of the exo-C1—Ccarboxyl and exo-C2—Ccarboxyl
bonds, together with distortion of the external aromatic ring C
to carboxyl C bond angles. It was intended in this work that,
together with a description of the hydrogen-bonding features
of four new DCPA salts, we would examine the complete set of
known ‘planar’ hydrogen DCPA structures and compare these
abnormal but interrelated features.
anion and since the number of characterized aliphatic exam-
ples is not great, we carried out the 1:1 stoichiometric reaction
of DCPA with a series of aliphatic amines. Our experience
indicated that such preparations generally yielded noncrys-
talline powders from methanol solution (a solvent of choice
for the aromatic salts), but if recrystallized from water, they
often gave crystals suitable for X-ray analysis. Using this
technique, small quantities were obtained of quality crystals of
the DCPA salts of the primary amine n-butylamine, the
secondary amines diethylamine and piperidine and the
tertiary amine triethylamine. These compounds are anhydrous
triethylaminium 2-carboxy-4,5-dichlorobenzoate, (I), diethyl-
aminium 2-carboxy-4,5-dichlorobenzoate, (II), and the
hydrated salts bis(butanaminium) 4,5-dichlorobenzene-1,2-
dicarboxylate monohydrate, (III), and bis(piperidinium) 4,5-
dichlorobenzene-1,2-dicarboxylate monohydrate, (IV), and
the structures are reported here (Figs. 1–4).
Because the known structures of the 1:1 aliphatic Lewis
base salts with DCPA, with the exception of the ammonium
salt (Mattes & Dorau, 1986), invariably have the ‘planar’
ꢁ
ꢂ
Acta Cryst. (2010). C66, o374–o380
Smith and Wermuth Four C8H3Cl2O4 salts o375

organic compounds
Figure 5
A perspective view of the zero-dimensional structure of the unit cell of
(I), showing the partial anion–aromatic ring overlap down a. Non-
associative H atoms have been omitted.
Figure 7
The two-dimensional hydrogen-bonded zigzag chains formed by exten-
sion of the cation–anion pairs, in the structure of (III), in a perspective
view of the unit cell. Non-associative H atoms have been omitted. For
symmetry codes, see Table 3.
Figure 6
The hydrogen-bonding chain extension of the cation–anion pair along the
c axial direction of the unit cell of (II). Non-associative H atoms have
been omitted and hydrogen bonds are shown as dashed lines. For
symmetry code (i), see Table 2.
Figure 8
Hydrogen-bonding expansion of the asymmetric unit of (IV), showing the
cyclic R44(18) and R55(17) associations. Non-associative H atoms have been
omitted. For symmetry codes, see Table 4.
Considering the 1:1 stoichiometric reaction conditions
employed in the preparation of all four compounds, which
should have resulted in 1:1 salts, compounds (III) and (IV) are
unusual, giving dianionic phthalate salts as well as being
hydrates, whereas (I) and (II) are the expected and more
common anhydrous 1:1 hydrogen phthalate salts. All members
of this set of compounds show low-dimensional hydrogen-
bonded structures: zero- in (I), one- in (II) and two-dimen-
sional in (III) and (IV) (Figs. 5–8). Also, all have at least one
N+—Hꢀ ꢀ ꢀOcarboxyl hydrogen-bonding interaction (Figs. 1–4),
(II) having two such interactions, but in compounds (III) and
(IV), the water O atom acts as an acceptor in an N+—Hꢀ ꢀ ꢀO
hydrogen bond (Tables 1–4). A listing of significant structural
parameters for the DCPA anions of (I) and (II), as well as
those for the complete set of ‘planar’ DCPA salts, is also made
(Table 5).
(Table 1). This results in discrete cation–anion units
(‘heterodimers’; Etter & Adsmond, 1990), giving a zero-
dimensional structure (Fig. 1). This structure therefore
represents only the fifth of its type among the known series of
1:1 DCPA salts, the others being the tetra-n-butylammonium
salt (Mattes & Dorau, 1986), the 1,8-bis(dimethylamino)-
naphthalene salt (Mallinson et al., 2003; Parkin et al., 2007),
the brucinium salt (Smith et al., 2007) and the 1,10-phenan-
throlinium salt (Smith et al., 2009c), although the tetra-
methylammonium salt of DCPA (Bozkurt et al., 2006) may
also be considered discrete on the basis of formal inter-
molecular N—Hꢀ ꢀ ꢀO hydrogen bonds. A unique discrete
‘heterotetramer’ (Etter & Adsmond, 1990) is found in the 1:1
compound with 2-aminopyrimidine (Smith et al., 2009a). The
only intermolecular associations in the structure of (I) are
weak anion–anion ꢀ–ꢀ interactions [ring centroid separation =
With compound (I) the only cation–anion hydrogen-
bonding association is asymmetric cyclic, involving both
carboxyl O-atom acceptors [graph set R21(4); Etter et al., 1990]
˚
3.6494 (8) A] due to partial aromatic ring overlap down the a
ꢁ
ꢂ
o376 Smith and Wermuth Four C8H3Cl2O4 salts
Acta Cryst. (2010). C66, o374–o380

organic compounds
groups and B bridging a carboxyl group and a water O-atom
acceptor. The water also bridges carboxyl groups giving much
larger conjoint cyclic interactions [graph sets R44(18) and
R55(17)] (Table 4). Duplex chains which lie along the c cell
direction are extended down the b direction giving a two-
dimensional sheet structure (Fig. 9). The conformations of the
two carboxyl groups in the ‘nonplanar’ DCPA dianions in (III)
and (IV) differ but not significantly [torsion angles C1—
C2—C21—O22 and C2—C1—C11—O11 are, respectively,
147.29 (15) and 125.00 (17)ꢃ for (III), and ꢁ141.41 (13) and
ꢁ118.74 (15)ꢃ for (IV)] since these values would be expected
to be affected by hydrogen-bonding environments.
There is an absence in (I)–(IV) of short intermolecular
Clꢀ ꢀ ꢀCl interactions such as has been found in the 1:1 DCPA
compounds with the 3- and 4-aminobenzoic acids (Smith et al.,
2008a). However, in one of the ‘planar’ structures, (II),
there are short intermolecular Clꢀ ꢀ ꢀOcarboxyl associations
ii
1
2
˚
[Cl4ꢀ ꢀ ꢀO22 = 2.9769 (17) A; symmetry code: (ii) ꢁx + 1, y ꢁ ,
1
ꢁz + ].
2
With the ‘planar’ DCPA monoanions which comprise 19 of
the total of 26 known examples within the series of known 1:1
compounds with both aromatic and aliphatic amines, there are
also other inherent structural features which are present,
including some which evoke checkCIF C alerts, as follows: (i)
long sp2–sp2 Cring—Ccarboxyl bond distances; (ii) distortion of
the external bond angles associated with the C—Ccarboxyl
bonds; (iii) short aromatic C3—Hꢀ ꢀ ꢀOcarboxyl and C6—
Hꢀ ꢀ ꢀOcarboxyl interactions. However, with point (iii), these
Figure 9
The two-dimensional hydrogen-bonded structure formed of (IV), viewed
down the b axis of the unit cell. Non-associative H atoms have been
omitted. For symmetry codes, see Table 4.
˚
short Cꢀ ꢀ ꢀO contacts [2.6714 (16) and 2.6602 (17) A for (I),
˚
and 2.663 (3) and 2.662 (2) A for (II)] are an artefact of the
axis of the unit cell (Fig. 5). With (I), the ‘planar’ DCPA
monoanion with the short intramolecular carboxyl–carboxyl
O—Hꢀ ꢀ ꢀO hydrogen bond is found (Tables 1 and 5).
With the diethylaminium salt, (II), the hydrogen-bonded
cation–anion ‘heterodimer’ (Fig. 2) is extended through the
second aminium H atom (Table 2) into a simple one-dimen-
sional chain structure which lies along the c axial direction in
the unit cell (Fig. 6). This structural motif is similar to that of
the diisopropylaminium salt (Smith & Wermuth, 2010a). The
DCPA anion in (II) also has the ‘planar’ conformation (Tables
2 and 5).
‘planar’ anion conformation. Table 5 lists the values relating to
points (i) and (ii) for (I) and (II), as well as the comparative
values for the intramolecular O—Hꢀ ꢀ ꢀO carboxyl hydrogen
bonds and the associated C2—C1—C11—O11 and C1—C2—
C21—O22 torsion angles for the full set of known 1:1 ‘planar’
DCPA compounds, and a remarkable consistency is observed.
Regarding point (i), the lengthening of the C1—C11 and C2—
˚
C21 bonds [1.5366 (19) and 1.5344 (19) A in (I), and 1.530 (3)
˚
and 1.521 (3) A in (II)] compares with the series bond-length
˚
range: 1.511 (6) A in the quinacrine salt (Smith et al., 2009) to
˚
1.538 (3) A in the 1,10-phenanthroline salt (Smith et al.,
2009c). A typical value for this bond in a ‘nonplanar’ example
˚
is 1.500 (2) A in the 2-carboxyanilinium–DCPA salt (Smith et
al., 2008b). Regarding point (ii), the exo-C1 and C2 ring angles
(C1—C2—C21 and C2—C1—C11) [128.16 (11) and
129.73 (11)ꢃ for (I), and 128.33 (17) and 128.49 (16)ꢃ in (II)]
compare with the range of 127.88 (16)ꢃ in the nicotinamide
salt (Smith et al., 2008a) to 129.73 (11)ꢃ in compound (I). The
distances for the intramolecular hydrogen bond range from
In the 2:1 monohydrate salt of n-butylamine with DCPA,
(III), the two cations (A and B) provide hydrogen-bonding
links between the DCPA ‘nonplanar’ dianions forming duplex
chain structures which extend along the b direction in the unit
cell (Fig. 7). The A and B aminium groups have different
interactive environments (Table 3), with B linking only DCPA
anions, while A links two anions and acts also as a donor to the
water molecule which bridges carboxyl groups. Within the
duplex chain structures are a series of cyclic conjoint
hydrogen-bonding interactions [graph sets R44(12) and R43(10)].
The N—Hꢀ ꢀ ꢀOwater links expand the chains into sheets
extending down the a cell direction in the two-dimensional
structure.
˚
2.34 (1) A in the tetra-n-butylammonium salt (Mattes &
˚
Dorau, 1986) to 2.4507 (16) A in the isopropylamine salt
(Smith & Wermuth, 2010b), the latter being associated with
the maximum deviation from planarity in the series, indicated
by the C2—C1—C11—O11 torsion angle of ꢁ156.69 (13)ꢃ.
Considering the high incidence of the ‘planar’ monoanionic
DCPA species among this set of salts, it is apparent that the
structural distortions invariably present in the anion, which
With the 2:1 monohydrate salt with piperidine, (IV), the
hydrogen-bonding expansion of the basic asymmetric unit
(Fig. 8) is similar to that in (III), involving the two cations A
and B in different environments, with A bridging carboxyl
ꢁ
ꢂ
Acta Cryst. (2010). C66, o374–o380
Smith and Wermuth Four C8H3Cl2O4 salts o377

organic compounds
Table 1
Hydrogen-bond geometry (A, ) for (I).
are a consequence of the internal carboxyl hydrogen bond, are
accommodated internally rather than by assuming the
‘nonplanar’ conformation.
ꢃ
˚
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
This present series of salts provides further examples of
low-dimensional hydrogen-bonded structure types in the
series of both 1:1 and 1:2 proton-transfer compounds of 4,5-
dichlorophthalic acid with aliphatic Lewis bases. The dimen-
sionality of the structure should be largely dictated by the type
of amine involved (primary, secondary or tertiary), but with
the 1:1 examples, the ‘planar’ internally hydrogen-bonded
hydrogen phthalate anion species is found and with it low-
dimensional hydrogen-bonded structures. This is also the case
with the ‘nonplanar’ 1:2 dianionic DCPA examples, (III) and
(IV). Furthermore, there is little variation in the conforma-
tional features of the monoanionic ‘planar’ DCPA anion
species.
N1A—H1Aꢀ ꢀ ꢀO21
N1A—H1Aꢀ ꢀ ꢀO22
O12—H12ꢀ ꢀ ꢀO21
0.910 (15)
0.910 (15)
0.99 (2)
2.569 (16)
1.837 (15)
1.44 (2)
3.1614 (15)
2.7433 (16)
2.4223 (14)
123.3 (12)
173.7 (14)
175 (2)
Table 2
Hydrogen-bond geometry (A, ) for (II).
ꢃ
˚
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N1A—H1Aꢀ ꢀ ꢀO11i
N1A—H2Aꢀ ꢀ ꢀO22
O12—H12ꢀ ꢀ ꢀO21
0.89 (2)
0.94 (3)
0.99 (3)
1.89 (2)
1.83 (3)
1.40 (3)
2.772 (2)
2.765 (3)
2.388 (2)
169.6 (19)
173 (3)
179 (4)
1
1
Symmetry code: (i) x; ꢁy þ ; z ꢁ .
2
2
Table 3
Hydrogen-bond geometry (A, ) for (III).
ꢃ
˚
Experimental
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
Compounds (I)–(IV) were synthesized by heating together for 10 min
under reflux 1 mmol quantities of 4,5-dichlorophthalic acid and,
respectively, triethylamine, diethylamine, n-butylamine and piper-
idine in methanol (50 ml). All preparations gave colourless powders
on complete evaporation of solvent but subsequent recrystallization
from water gave, in all cases, small quantities of colourless crystals
suitable for X-ray analysis [m.p.: 353 K in (I), 443 K in (II), 405 K in
(III) and 447 K in (IV)].
N1A—H11Aꢀ ꢀ ꢀO12i
N1A—H12Aꢀ ꢀ ꢀO1Wii
N1A—H13Aꢀ ꢀ ꢀO21
N1B—H11Bꢀ ꢀ ꢀO22
N1B—H12Bꢀ ꢀ ꢀO21iii
N1B—H13Bꢀ ꢀ ꢀO11iv
O1W—H11Wꢀ ꢀ ꢀO12
O1W—H12Wꢀ ꢀ ꢀO22iii
0.85 (2)
0.91 (2)
0.94 (2)
0.89 (2)
0.89 (3)
0.89 (3)
0.89 (3)
0.91 (3)
1.92 (2)
1.92 (2)
1.94 (2)
2.00 (3)
1.90 (3)
1.86 (3)
1.84 (3)
1.87 (3)
2.762 (2)
2.799 (2)
2.831 (2)
2.847 (2)
2.7737 (19)
2.7481 (19)
2.723 (2)
2.7648 (18)
170 (2)
164 (2)
158.4 (17)
158.9 (19)
167.9 (17)
170 (2)
173 (2)
166 (3)
Symmetry codes: (i) ꢁx þ 1; ꢁy þ 1; ꢁz þ 1; (ii) x þ 1; y; z; (iii) ꢁx þ 1; ꢁy; ꢁz þ 1;
(iv) x; y ꢁ 1; z.
Compound (I)
Crystal data
C6H16N+ꢀC8H3Cl2O4
Data collection
ꢁ
3
˚
V = 1582.3 (2) A
Z = 4
Oxford Diffraction Gemini-S CCD-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.926, Tmax = 0.980
5638 measured reflections
2802 independent reflections
2159 reflections with I > 2ꢄ(I)
Rint = 0.022
Mr = 336.20
Monoclinic, P21=c
Mo Kꢂ radiation
ꢃ = 0.42 mmꢁ1
T = 200 K
0.40 ꢄ 0.40 ꢄ 0.30 mm
˚
a = 7.3206 (7) A
˚
b = 11.2201 (7) A
˚
c = 19.4813 (12) A
ꢁ = 98.576 (7)ꢃ
Refinement
R[F2 > 2ꢄ(F2)] = 0.037
wR(F2) = 0.106
S = 1.05
2802 reflections
184 parameters
H atoms treated by a mixture of
independent and constrained
refinement
Data collection
Oxford Diffraction Gemini-S CCD-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.96, Tmax = 0.98
10740 measured reflections
3098 independent reflections
2638 reflections with I > 2ꢄ(I)
Rint = 0.020
ꢁ3
˚
Áꢅmax = 0.38 e A
ꢁ3
˚
Áꢅmin = ꢁ0.26 e A
Refinement
Compound (III)
R[F2 > 2ꢄ(F2)] = 0.029
wR(F2) = 0.077
S = 1.04
3098 reflections
193 parameters
H atoms treated by a mixture of
independent and constrained
refinement
Crystal data
2C4H12N+ꢀC8H2Cl2O42ꢁꢀH2O
ꢆ = 67.777 (9)ꢃ
V = 1058.62 (18) A
Z = 2
Mo Kꢂ radiation
ꢃ = 0.33 mmꢁ1
T = 200 K
ꢁ3
˚
Áꢅmax = 0.23 e A
3
˚
Mr = 399.30
Triclinic, P1
ꢁ3
˚
Áꢅmin = ꢁ0.24 e A
˚
a = 8.1362 (6) A
˚
b = 9.3043 (11) A
˚
c = 15.406 (1) A
Compound (II)
ꢂ = 78.678 (7)ꢃ
ꢁ = 85.846 (6)ꢃ
0.55 ꢄ 0.30 ꢄ 0.20 mm
Crystal data
C4H12N+ꢀC8H3Cl2O4
ꢁ
3
˚
V = 1465.2 (3) A
Z = 4
Data collection
Mr = 308.14
Monoclinic, P21=c
Mo Kꢂ radiation
ꢃ = 0.45 mmꢁ1
T = 200 K
0.35 ꢄ 0.35 ꢄ 0.15 mm
Oxford Diffraction Gemini-S CCD-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.865, Tmax = 0.940
15869 measured reflections
4851 independent reflections
3858 reflections with I > 2ꢄ(I)
Rint = 0.041
˚
a = 8.9588 (13) A
˚
b = 9.9042 (11) A
˚
c = 17.062 (3) A
ꢁ = 104.580 (14)ꢃ
ꢁ
ꢂ
o378 Smith and Wermuth Four C8H3Cl2O4 salts
Acta Cryst. (2010). C66, o374–o380

organic compounds
Table 4
Hydrogen-bond geometry (A, ) for (IV).
Refinement
ꢃ
˚
R[F2 > 2ꢄ(F2)] = 0.038
wR(F2) = 0.103
S = 0.96
4805 reflections
268 parameters
H atoms treated by a mixture of
independent and constrained
refinement
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
ꢁ3
˚
Áꢅmax = 0.26 e A
N1A—H11Aꢀ ꢀ ꢀO21i
N1A—H12Aꢀ ꢀ ꢀO11
N1B—H11Bꢀ ꢀ ꢀO11i
N1B—H12Bꢀ ꢀ ꢀO1W
O1W—H11Wꢀ ꢀ ꢀO12
O1W—H12Wꢀ ꢀ ꢀO22ii
0.90 (2)
1.80 (2)
2.6820 (17)
2.8085 (17)
2.8054 (16)
2.7866 (18)
2.7490 (17)
2.7639 (17)
164.0 (17)
168.4 (16)
170.7 (16)
153.1 (15)
176 (2)
ꢁ3
˚
Áꢅmin = ꢁ0.29 e A
0.914 (19)
0.896 (17)
0.975 (19)
0.82 (2)
1.907 (19)
1.917 (17)
1.882 (19)
1.93 (2)
H atoms potentially involved in hydrogen-bonding interactions
were all located in difference maps and their positional and isotropic
displacement parameters were refined; the resulting O—H and N—H
distances are given in Tables 1–4. Other H atoms were included at
0.84 (2)
1.96 (2)
162 (2)
1
2
1
2
Symmetry codes: (i) ꢁx; y ꢁ ; ꢁz þ ; (ii) ꢁx; ꢁy þ 2; ꢁz.
˚
calculated positions [C—H = 0.95 (aromatic) or 0.98–0.99 A
Refinement
(aliphatic)] and treated as riding atoms, with Uiso(H) values of
1.2Ueq(C).
R[F2 > 2ꢄ(F2)] = 0.046
wR(F2) = 0.145
S = 1.18
4851 reflections
260 parameters
H atoms treated by a mixture of
independent and constrained
refinement
For all compounds, data collection: CrysAlis Pro (Oxford
Diffraction, 2009); cell refinement: CrysAlis Pro; data reduction:
CrysAlis Pro. Program(s) used to solve structure: SHELXS97
(Sheldrick, 2008) for (I), (II) and (IV); SIR92 (Altomare et al., 1994)
for (III). For all compounds, program(s) used to refine structure:
SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999);
molecular graphics: PLATON (Spek, 2009); software used to prepare
material for publication: PLATON.
ꢁ3
˚
Áꢅmax = 0.41 e A
ꢁ3
˚
Áꢅmin = ꢁ0.29 e A
Compound (IV)
Crystal data
2C5H12N+ꢀC8H2Cl2O42ꢁꢀH2O
3
˚
V = 2111.8 (3) A
Z = 4
Mr = 423.32
Monoclinic, P21=c
Mo Kꢂ radiation
ꢃ = 0.34 mmꢁ1
T = 200 K
0.35 ꢄ 0.20 ꢄ 0.18 mm
The authors acknowledge financial support from the
Australian Research Council and the Faculty of Science and
Technology, Queensland University of Technology and the
School of Biomolecular and Physical Sciences, Griffith
University.
˚
a = 13.8481 (10) A
˚
b = 10.5937 (8) A
˚
c = 14.6129 (10) A
ꢁ = 99.903 (7)ꢃ
Data collection
Oxford Diffraction Gemini-S CCD-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.701, Tmax = 0.980
26626 measured reflections
4805 independent reflections
3570 reflections with I > 2ꢄ(I)
Rint = 0.057
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GD3347). Services for accessing these data are
described at the back of the journal.
Table 5
Comparative structural parameters (A, ) and structural classification for the series of ‘planar’ 1:1 DCPA salts of the named Lewis base types.
ꢃ
˚
Lewis base type Structure type† C1—C11
C2—C21
C1—C2—C21 C2—C1—C11 O12ꢀ ꢀ ꢀO21 C1—C2—C21—O22 C2—C1—C11—O11
TEAa
0
2
1
1
1
1
1
0
0
0
1
0
1
2
1
1
0
0
2
2
1.5366 (19) 1.5344 (19) 128.16 (11)
1.530 (3) 1.521 (3) 128.33 (17)
1.5189 (18) 1.5297 (18) 128.32 (11)
129.73 (11)
128.49 (16)
128.14 (11)
128.2 (2)
127.8 (5)
128.2 (2)
128.9 (2)
128.9 (8)
128.4 (2)
128.93 (16)
128.0 (5)
2.4223 (14)
2.388 (2)
2.4507 (16)
2.381 (3)
2.381 (8)
2.392 (3)
2.380 (3)
2.34 (1)
178.46 (13)
ꢁ172.41 (19)
161.01 (13)
ꢁ170.8 (2)
ꢁ173.7 (6)
ꢁ174.6 (3)
180
179.64 (13)
175.50 (19)
ꢁ156.69 (13)
ꢁ176.7 (2)
173.6 (5)
174.2 (3)
180
168 (1)
163.9 (2)
DEAa
IPAb
DIPAc
HMTc
1.523 (3)
1.529 (9)
1.522 (4)
1.528 (3)
1.523 (13)
1.523 (3)
1.531 (3)
1.521 (8)
1.527 (2)
1.527 (5)
1.516 (3)
1.523 (8)
1.534 (4)
1.529 (3)
1.529 (14)
1.535 (3)
1.528 (3)
1.515 (11)
1.532 (2)
1.531 (5)
128.5 (2)
129.3 (5)
128.8 (2)
128.9 (2)
128.3 (9)
128.9 (2)
127.88 (16)
128.3 (5)
INIPAd
TMAe
TBAf
173 (1)
BRUg
2.441 (3)
2.410 (2)
2.393 (8)
ꢁ177.8 (2)
172.58 (18)
ꢁ178.6 (7)
NICAh
INICAh
AMPMh
PMPYi
TFMANj
8-AQk
8-HQk
BTMAPl
PHENm
QACn‡
QACn‡
ꢁ178.68 (19)
173.0 (7)
128.72 (14)
128.9 (3)
128.90 (14)
128.8 (3)
2.4037 (19) ꢁ179.70 (16)
ꢁ170.16 (16)
ꢁ173.2 (3)
179.50 (16)
174.38 (15)
171.3 (2)
179.32 (16)
ꢁ168.30 (16)
ꢁ172.4 (5)
ꢁ174.2 (5)
2.376 (4)
169.9 (3)
1.5161 (19) 1.520 (2)
128.35 (13)
129.27 (14)
127.97 (19)
129.09 (15)
128.55 (15)
129.6 (5)
128.69 (12)
128.36 (14)
128.88 (19)
129.00 (14)
129.18 (16)
128.4 (4)
2.3908 (17) ꢁ179.04 (16)
2.3922 (18) ꢁ175.88 (15)
1.525 (2)
1.527 (3)
1.536 (2)
1.538 (2)
1.527 (7)
1.522 (8)
1.534 (2)
1.518 (3)
1.534 (2)
1.536 (3)
1.527 (7)
1.511 (6)
2.389 (2)
2.4004 (19)
ꢁ176.6 (2)
172.41 (15)
2.4054 (19) ꢁ179.53 (16)
2.366 (7)
2.377 (5)
177.0 (5)
178.5 (5)
128.2 (4)
129.0 (4)
(a) This work (TEA is triethylamine and DEA is diethylamine); (b) Smith & Wermuth (2010b) (IPA is isopropylamine); (c) Smith & Wermuth (2010a) (DIPA is diisopropylamine and
HMT is hexamethylenetetramine); (d) Smith & Wermuth (2010e) (INIPA is isonipecotamide); (e) Bozkurt et al. (2006) (TMA is the tetramethylammonium ion); (f) Mattes & Dorau
(1986) (TBA is the tetra-n-butylammonium ion); (g) Smith et al. (2007) (BRU is brucine); (h) Smith et al. (2009a) (NICA is nicotinamide, INICA is isonicotinamide and AMPM is
˘
¨
¨
¨
¨
2-aminopyrimidine); (i) Smith & Wermuth (2010d) (PMPY is 4-methylpyridine); (j) Odabas¸oglu & Buyukgungor (2007) [TFMAN is 3-(trifluoromethyl)aniline]; (k) Smith et al. (2008b)
(8-AQ is 8-aminoquinoline and 8-HQ is 8-hydroxyquinoline); (l) Mallinson et al. (2003); Parkin et al. (2007) [BTMAP is 1,8-bis(trimethylamino)naphthalene]; (m) Smith et al. (2009c)
(PHEN is 1,10-phenanthroline); (n) Smith et al. (2009) (QAC is quinacrine). † 0 = zero-dimensional; 1 = one-dimensional; 2 = two-dimensional. ‡ For the quinacrine salt, there are
two independent DCPA anions in the asymmetric unit.
ꢁ
ꢂ
Acta Cryst. (2010). C66, o374–o380
Smith and Wermuth Four C8H3Cl2O4 salts o379

organic compounds
¨
Sheldrick, G. M. (1996). SADABS. University of Gottingen, Germany.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
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o380 Smith and Wermuth Four C8H3Cl2O4 salts
Acta Cryst. (2010). C66, o374–o380