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Crystal structures of 1,4-di-aza-bicyclo-[2.2.2]octan-1-ium 4-nitro-benzoate dihydrate and 1,4-di-aza-bicyclo-[2.2.2]octane-1,4-diium bis-(4-nitro-benzoate): the influence of solvent upon the stoichiometry of the formed salt.

Akhmad Aznan AM, Abdullah Z, Tiekink ER - Acta Crystallogr Sect E Struct Rep Online (2014)

Bottom Line: The global crystal structure comprises alternating layers of water mol-ecules and ion pairs stacked along the c axis.In the crystal of (2), the three-ion aggregates are assembled into a three-dimensional architecture by a large number of methyl-ene-carboxyl-ate/nitro C-H⋯O inter-actions as well as π-π contacts between inversion-related benzene rings [inter-centroid distances = 3.5644 (16) and 3.6527 (16) Å].The cations and anions assemble into alternating layers along the c axis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.

ABSTRACT
The 1:1 co-crystallization of 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO) with 4-nitro-benzoic acid in ethanol-water (3/1) gave the salt dihydrate C6H13N2 (+)·C7H4NO4 (-)·2H2O, (1), whereas from methanol, the salt C6H14N2 (2+)·2C7H4NO4 (-), (2), was isolated. In (1), the cation and anion are linked by a strong N-H⋯O hydrogen bond, and the carboxyl-ate anion is close to planar [dihedral angle between terminal residues = 6.83 (9)°]. In (2), a three-ion aggregate is assembled by two N-H⋯O hydrogen bonds, and the carboxyl-ate anions are again close to planar [dihedral angles between terminal residues = 1.7 (3) and 5.9 (3)°]. Through the inter-vention of solvent water mol-ecules, which self-assemble into helical supra-molecular chains along the b axis, the three-dimensional architecture in (1) is stabilized by water-DABCO O-H⋯N and water-carboxyl-ate O-H⋯O hydrogen bonds, with additional stability afforded by C-H⋯O inter-actions. The global crystal structure comprises alternating layers of water mol-ecules and ion pairs stacked along the c axis. In the crystal of (2), the three-ion aggregates are assembled into a three-dimensional architecture by a large number of methyl-ene-carboxyl-ate/nitro C-H⋯O inter-actions as well as π-π contacts between inversion-related benzene rings [inter-centroid distances = 3.5644 (16) and 3.6527 (16) Å]. The cations and anions assemble into alternating layers along the c axis.

No MeSH data available.


Related in: MedlinePlus

The mol­ecular structures of the three independent constituents of (2), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines (see Table 2 ▶ for details).
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fig2: The mol­ecular structures of the three independent constituents of (2), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines (see Table 2 ▶ for details).

Mentions: The asymmetric unit of (2) comprises a 1,4-di­aza­bicyclo­[2.2.2]octane-1,4-diium di-cation and two 4-nitro­benzoate anions (Fig. 2 ▶). In the dication, the N3—C [1.483 (3)–1.487 (3) Å] and N4—C [1.486 (3)–1.487 (3) Å] bond lengths are experimentally equivalent and consistent with diprotonation. In the anions, the disparity of the C1—O1, O2 bond lengths, i.e. 1.281 (3) and 1.228 (3) Å, is slightly greater than that in C8—O5, O6 of 1.273 (3) and 1.231 (3) Å, respectively. In each case the longer bond forms a strong N—H⋯O hydrogen bond (Table 2 ▶). In order to confirm the location of the acidic hydrogen atoms, an unrestrained refinement was conducted, see Refinement for details. While there was some elongation in the N—H bond lengths, unrestrained refinement confirmed protonation at both nitro­gen atoms. In the O1-containing anion, the dihedral angles between the central ring and the carboxyl­ate and nitro groups are 7.0 (3) and 8.7 (2)°, respectively, and the dihedral angle between the terminal groups is 1.7 (3)°. The comparable angles for the O5-containing anion are 2.2 (3), 7.4 (2) and 5.9 (3)°, respectively. As discussed below in Supra­molecular features, the ions participate in strong N—H⋯O hydrogen bonds, forming a three-ion aggregate (Fig. 2 ▶) in which the dihedral angle between the benzene rings is 9.26 (14)°.


Crystal structures of 1,4-di-aza-bicyclo-[2.2.2]octan-1-ium 4-nitro-benzoate dihydrate and 1,4-di-aza-bicyclo-[2.2.2]octane-1,4-diium bis-(4-nitro-benzoate): the influence of solvent upon the stoichiometry of the formed salt.

Akhmad Aznan AM, Abdullah Z, Tiekink ER - Acta Crystallogr Sect E Struct Rep Online (2014)

The mol­ecular structures of the three independent constituents of (2), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines (see Table 2 ▶ for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120614&req=5

fig2: The mol­ecular structures of the three independent constituents of (2), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines (see Table 2 ▶ for details).
Mentions: The asymmetric unit of (2) comprises a 1,4-di­aza­bicyclo­[2.2.2]octane-1,4-diium di-cation and two 4-nitro­benzoate anions (Fig. 2 ▶). In the dication, the N3—C [1.483 (3)–1.487 (3) Å] and N4—C [1.486 (3)–1.487 (3) Å] bond lengths are experimentally equivalent and consistent with diprotonation. In the anions, the disparity of the C1—O1, O2 bond lengths, i.e. 1.281 (3) and 1.228 (3) Å, is slightly greater than that in C8—O5, O6 of 1.273 (3) and 1.231 (3) Å, respectively. In each case the longer bond forms a strong N—H⋯O hydrogen bond (Table 2 ▶). In order to confirm the location of the acidic hydrogen atoms, an unrestrained refinement was conducted, see Refinement for details. While there was some elongation in the N—H bond lengths, unrestrained refinement confirmed protonation at both nitro­gen atoms. In the O1-containing anion, the dihedral angles between the central ring and the carboxyl­ate and nitro groups are 7.0 (3) and 8.7 (2)°, respectively, and the dihedral angle between the terminal groups is 1.7 (3)°. The comparable angles for the O5-containing anion are 2.2 (3), 7.4 (2) and 5.9 (3)°, respectively. As discussed below in Supra­molecular features, the ions participate in strong N—H⋯O hydrogen bonds, forming a three-ion aggregate (Fig. 2 ▶) in which the dihedral angle between the benzene rings is 9.26 (14)°.

Bottom Line: The global crystal structure comprises alternating layers of water mol-ecules and ion pairs stacked along the c axis.In the crystal of (2), the three-ion aggregates are assembled into a three-dimensional architecture by a large number of methyl-ene-carboxyl-ate/nitro C-H⋯O inter-actions as well as π-π contacts between inversion-related benzene rings [inter-centroid distances = 3.5644 (16) and 3.6527 (16) Å].The cations and anions assemble into alternating layers along the c axis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.

ABSTRACT
The 1:1 co-crystallization of 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO) with 4-nitro-benzoic acid in ethanol-water (3/1) gave the salt dihydrate C6H13N2 (+)·C7H4NO4 (-)·2H2O, (1), whereas from methanol, the salt C6H14N2 (2+)·2C7H4NO4 (-), (2), was isolated. In (1), the cation and anion are linked by a strong N-H⋯O hydrogen bond, and the carboxyl-ate anion is close to planar [dihedral angle between terminal residues = 6.83 (9)°]. In (2), a three-ion aggregate is assembled by two N-H⋯O hydrogen bonds, and the carboxyl-ate anions are again close to planar [dihedral angles between terminal residues = 1.7 (3) and 5.9 (3)°]. Through the inter-vention of solvent water mol-ecules, which self-assemble into helical supra-molecular chains along the b axis, the three-dimensional architecture in (1) is stabilized by water-DABCO O-H⋯N and water-carboxyl-ate O-H⋯O hydrogen bonds, with additional stability afforded by C-H⋯O inter-actions. The global crystal structure comprises alternating layers of water mol-ecules and ion pairs stacked along the c axis. In the crystal of (2), the three-ion aggregates are assembled into a three-dimensional architecture by a large number of methyl-ene-carboxyl-ate/nitro C-H⋯O inter-actions as well as π-π contacts between inversion-related benzene rings [inter-centroid distances = 3.5644 (16) and 3.6527 (16) Å]. The cations and anions assemble into alternating layers along the c axis.

No MeSH data available.


Related in: MedlinePlus