(2SR,4aSR,8aSR)-6-Oxoperhydro­naphthalene-2-carboxylic acid

In the title racemic compound, C11H16O3, the mol­ecule adopts a conformation that places its carboxyl group in an equatorial position. Mol­ecules aggregate by hydrogen-bond pairing of carboxyl groups, yielding centrosymmetric dimers that are arranged into layers in the (020) planes

4-(2-Benzoyl­ethyl)benzoic acid

The title compound, C16H14O3, adopts a conformation in which each functional group is almost coplanar with its adjacent ring, while the two aromatic rings are twisted with respect to one another with a dihedral angle of 78.51 (3)°. The compound dimerizes by standard centrosymmetric hydrogen-bonded carboxyl pairing [O⋯O = 2.6218 (11) Å and O—H⋯O = 176 (2)°]. The packing includes two inter­molecular C—H⋯O close contacts with the ketone group

(-)-Isosantonic acid: Alteration of the hydrogen-bonding mode by configurational inversion at a single centre in a γ,ε- diketocarboxylic acid

The title diketo acid, (1R,3aS,6aS,7R,9S)-(-)-α,3a,7-trimethyl-5,8- dioxo-1,4-ethanoperhydropentalene-1-acetic acid (C15H 20O4), is shown to aggregate in the crystal structure as acid-to-ketone hydrogen-bonding catemers, whose chains follow 21 screw axes from each carboxyl to a ketone in a neighbouring molecule [O⋯O = 2.7472(13) and O⋯H - O = 172.7(17)°]. Two parallel counterdirectional screw-related single-strand hydrogen-bonding chains pass through the cell in the a direction. Six intermolecular C - H⋯O=C close contacts are found. Comparisons are drawn with a diastereomer having the opposite configuration at the methylated chiral centre adjacent to the carboxyl group.Fil: Zinczuk, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Ruveda, Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Lalancette, Roger A.. Rutgers University; Estados UnidosFil: Thompson, Hugh W.. Rutgers University; Estados Unido

3-Acetyl­benzoic acid

In the crystal structure of the title compound, C9H8O3, essentially planar mol­ecules [the carboxyl group makes a dihedral angle of 4.53 (7)° with the plane of the ring, while the acid group forms a dihedral angle of 3.45 (8)° to the ring] aggregate by centrosymmetric hydrogen-bond pairing of ordered carboxyl groups. This yields dimers which have two orientations in a unit cell, creating a herringbone pattern. In addition, two close C—H⋯O inter­molecular contacts exist: one is between a methyl H atom and the ketone of a symmetry-related mol­ecule and the other involves a benzene H atom and the carboxyl group O atom of another mol­ecule. The crystal studied was a non-merohedral twin with twin law [100, 00, 0] and a domain ratio of 0.8104(14): 0.1896(14)

The hydro­chloride salt of l-ecgonine, a congener of cocaine

The title compound, (1R,2R,3S,5S,8S)-3-hydr­oxy-8-methyl-8-azoniabicyclo­[3.2.1]octane-2-carboxylic acid chloride, C9H16NO3 +·Cl−, is both a metabolite and a precursor of the tropane alkaloid l-cocaine. The carboxyl group is not involved in dimerization, but instead donates a hydrogen bond to the chloride counter-ion, which participates in two additional hydrogen bonds. The chloride ion is thus trigonally hydrogen bonded to three l-ecgonine cations. The quarternary N proton is intra­molecularly hydrogen bonded to the carboxyl C=O group, an arrangement identical to that reported for both (−)-nor­cocaine and the tetrachloroaurate(III) salt of l-cocaine. One close inter­molecular C—H⋯O contact exists

(2RS,8aRS)-6-Oxo-1,2,3,4,6,7,8,8a-octa­hydro­naphthalene-2-carboxylic acid

The title racemate, C11H14O3, aggregates in the crystal structure as acid-to-ketone O—H⋯O hydrogen-bonding catemers whose components are glide-related. The relative stereochemistry at the carboxyl group arises spontaneously during the synthesis. Two inter­molecular C—H⋯O=C close contacts were found, both involving the acid group

4-Oxocyclo­hexa­neacetic acid: catemeric hydrogen bonding and spontaneous resolution of a single conformational enanti­omer in an achiral ∊-keto acid

The asymmetric unit of the title compound, C8H12O3, consists of a single conformational enanti­omer, which aggregates in the catemeric acid-to-ketone hydrogen-bonding mode [O⋯O = 2.682 (4) Å and O—H⋯O = 172 (6)°]. Four hydrogen-bonding chains of translationally related mol­ecules pass through the cell orthogonal to the 43 screw axis along c, alternating in the 110 and the 10 direction, with alignment with respect to this axis of + + − −. Successive chains are rotated by 90° around the c axis. One C—H⋯O=C close contact, involving the carboxyl group, exists

Chlorido{N-[2-(diphenylphosphanyl)- benzylidene]-2-(2-thienyl)ethanamine-ĸ²N,P}methylpalladium(II) dichloromethane hemisolvate

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8-(Naphthalen-1-yl)quinoline

In the title mol­ecule, C19H13N, the angle between the mean planes of the naphthalene and quinoline ring systems is 68.59 (2)°. The compound is of inter­est with respect to its potential for spontaneous resolution. In the crystal structure, the R and S isomers are arranged in alternating homochiral layers. The mol­ecules of a given layer are oriented with their major axes (i.e. the axis perpendicular to the interannular bond) in the same direction and their naphthalene and quinoline ring systems are arranged parallel. Like the configurations, this orientation alternates in adjacent layers