Abstract:The ring system of the title compound, C(13)H(18)O(3), was synthesized by addition of ethyl acrylate to the dienamine of 2-octalone. The keto acid aggregates in the solid as acid-to-acid dimers [O...O = 2.663 (2) A and O[bond]H...O = 170 (3) degrees ] whose centrosymmetric hydrogen bonds lie across the a edges and the center of the chosen cell. Three intermolecular C[bond]H...O close contacts within 2.7 A were found involving the ketone group.
“…The carboxylic acid moiety is an important structural feature that occurs frequently in crystal engineering and biology. − In general, structures of carboxylic acids in the solid state are dominated by dimers in which the carbonyl oxygen and hydroxyl groups act as donors and acceptors. ,− The structure of this hydrogen-bonded dimer is shown in Figure . 1 Schematic representation of a typical carboxylic acid dimer with the crystallographically generated atoms as X‘.…”
Section: Introductionmentioning
confidence: 99%
“…As also shown in Figure , the full, real space hydrogen bond scheme is often developed via a crystallographic center of inversion. − However, the presence of a carboxylic acid group does not always imply the presence of a dimeric structure and two-dimensional networks and chains have also been observed. In systems where the dimeric structure is observed, the degenerate nature of the atoms involved in the hydrogen-bonded carboxylic acid dimer has attracted the interest of the theoretical community as a model for proton transfer. ,− …”
The solid-state structure of 4-iodobenzoic acid has been confirmed by variable temperature X-ray diffraction, variable temperature solid-state NMR and differential scanning calorimetry. 4-iodobenzoic acid crystallizes in the space group P2(1)/n, and dimerizes in the solid state about a center of inversion. Using extensive X-ray crystallographic data collections, the placement of the carboxylate H atoms from the residual electron density in difference Fourier maps was determined. The position of the electron density associated with the proton is found to vary with temperature in that the population of the disordered sites changes with varying temperature. Determination of the crystal structure between the temperatures of 248 and 198 K was not possible due to a phase transition, an endothermic event occurring at 230.77 K. The phase transition is also indicated by a change in the relaxation time of the ring carbon atoms in the solid-state NMR data. Though the dominating force in the dimeric unit in the solid state is the presence of strong hydrogen bonds, there are also van der Waals forces present between the iodine atoms. In the layered structure, the iodine-iodine distance is within the van der Waals contact radii, an interaction which causes a deformation in the electron density of the iodine atoms.
“…The carboxylic acid moiety is an important structural feature that occurs frequently in crystal engineering and biology. − In general, structures of carboxylic acids in the solid state are dominated by dimers in which the carbonyl oxygen and hydroxyl groups act as donors and acceptors. ,− The structure of this hydrogen-bonded dimer is shown in Figure . 1 Schematic representation of a typical carboxylic acid dimer with the crystallographically generated atoms as X‘.…”
Section: Introductionmentioning
confidence: 99%
“…As also shown in Figure , the full, real space hydrogen bond scheme is often developed via a crystallographic center of inversion. − However, the presence of a carboxylic acid group does not always imply the presence of a dimeric structure and two-dimensional networks and chains have also been observed. In systems where the dimeric structure is observed, the degenerate nature of the atoms involved in the hydrogen-bonded carboxylic acid dimer has attracted the interest of the theoretical community as a model for proton transfer. ,− …”
The solid-state structure of 4-iodobenzoic acid has been confirmed by variable temperature X-ray diffraction, variable temperature solid-state NMR and differential scanning calorimetry. 4-iodobenzoic acid crystallizes in the space group P2(1)/n, and dimerizes in the solid state about a center of inversion. Using extensive X-ray crystallographic data collections, the placement of the carboxylate H atoms from the residual electron density in difference Fourier maps was determined. The position of the electron density associated with the proton is found to vary with temperature in that the population of the disordered sites changes with varying temperature. Determination of the crystal structure between the temperatures of 248 and 198 K was not possible due to a phase transition, an endothermic event occurring at 230.77 K. The phase transition is also indicated by a change in the relaxation time of the ring carbon atoms in the solid-state NMR data. Though the dominating force in the dimeric unit in the solid state is the presence of strong hydrogen bonds, there are also van der Waals forces present between the iodine atoms. In the layered structure, the iodine-iodine distance is within the van der Waals contact radii, an interaction which causes a deformation in the electron density of the iodine atoms.
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