N,N-Diformylmescaline: A novel analogue of mescaline detected in Queensland.

N,N-Diformylmescaline, a novel analogue of mescaline, has recently been detected in Australia in two unrelated seizures. To confirm the identification, a three-step synthesis from 3,4,5-trimethoxyphenylacetic acid was devised. However, purification of the final product proved problematic with the compound prone to degradation in solution. Analysis of the compound by LC-MS indicated that the compound was unstable under acidic and basic conditions, breaking down to N-formylmescaline. Further degradation to mescaline was observed when the compound was dissolved in hydrochloric acid for an extended period of time suggesting that N,N-diformylmescaline may be a prodrug for mescaline. The GC-MS, NMR and FTIR data for the seized compound are presented along with details of the synthesis and studies of the compound's stability in solution.

Unusual 4-arsonoanilinium cationic species in the hydrochloride salt of (4-aminophenyl)arsonic acid and formed in the reaction of the acid with copper(II) sulfate, copper(II) chloride and cadmium chloride.

Structures having the unusual protonated 4-arsonoanilinium species, namely in the hydrochloride salt, C6H9AsNO3+·Cl-, (I), and the complex salts formed from the reaction of (4-aminophenyl)arsonic acid (p-arsanilic acid) with copper(II) sulfate, i.e. hexaaquacopper(II) bis(4-arsonoanilinium) disulfate dihydrate, (C6H9AsNO3)2[Cu(H2O)6](SO4)2·2H2O, (II), with copper(II) chloride, i.e. poly[bis(4-arsonoanilinium) [tetra-µ-chlorido-cuprate(II)]], {(C6H9AsNO3)2[CuCl4]}n, (III), and with cadmium chloride, i.e. poly[bis(4-arsonoanilinium) [tetra-µ-chlorido-cadmate(II)]], {(C6H9AsNO3)2[CdCl4]}n, (IV), have been determined. In (II), the two 4-arsonoanilinium cations are accompanied by [Cu(H2O)6]2+ cations with sulfate anions. In the isotypic complex salts (III) and (IV), they act as counter-cations to the {[CuCl4]2-}n or {[CdCl4]2-}n anionic polymer sheets, respectively. In (II), the [Cu(H2O)6]2+ ion sits on a crystallographic centre of symmetry and displays a slightly distorted octahedral coordination geometry. The asymmetric unit for (II) contains, in addition to half the [Cu(H2O)6]2+ ion, one 4-arsonoanilinium cation, a sulfate dianion and a solvent water molecule. Extensive O-H...O and N-H...O hydrogen bonds link all the species, giving an overall three-dimensional structure. In (III), four of the chloride ligands are related by inversion [Cu-Cl = 2.2826 (8) and 2.2990 (9) Å], with the other two sites of the tetragonally distorted octahedral CuCl6 unit occupied by symmetry-generated Cl-atom donors [Cu-Cl = 2.9833 (9) Å], forming a two-dimensional coordination polymer network substructure lying parallel to (001). In the crystal, the polymer layers are linked across [001] by a number of bridging hydrogen bonds involving N-H...Cl interactions from head-to-head-linked As-O-H...O 4-arsonoanilinium cations. A three-dimensional network structure is formed. CdII compound (IV) is isotypic with CuII complex (III), but with the central CdCl6 complex repeat unit having a more regular M-Cl bond-length range [2.5232 (12)-2.6931 (10) Å] compared to that in (III). This series of compounds represents the first reported crystal structures having the protonated 4-arsonoanilinium species.

Crystal structures and hydrogen bonding in the isotypic series of hydrated alkali metal (K, Rb and Cs) complexes with 4-amino-phenyl-arsonic acid.

The structures of the alkali metal (K, Rb and Cs) complex salts with 4-amino-phenyl-arsonic acid (p-arsanilic acid) manifest an isotypic series with the general formula [M2(C6H7AsNO3)2(H2O)3], with M = K {poly[di-µ3-4-amino-phenyl-arsonato-tri-µ2-aqua-dipotassium], [K2(C6H7AsNO3)2(H2O)3], (I)}, Rb {poly[di-µ3-4-amino-phenyl-arsonato-tri-µ2-aqua-dirubidium], [Rb2(C6H7AsNO3)2(H2O)3], (II)}, and Cs {poly[di-µ3-4-amino-phenyl-arsonato-tri-µ2-aqua-dirubidium], [Cs2(C6H7AsNO3)2(H2O)3], (III)}, in which the repeating structural units lie across crystallographic mirror planes containing two independent and different metal cations and a bridging water mol-ecule, with the two hydrogen p-arsanilate ligands and the second water mol-ecule lying outside the mirror plane. The bonding about the two metal cations in all complexes is similar, one five-coordinate, the other progressing from five-coordinate in (I) to eight-coordinate in both (II) and (III), with overall M-O bond-length ranges of 2.694 (5)-3.009 (7) (K), 2.818 (4)-3.246 (4) (Rb) and 2.961 (9)-3.400 (10) Š(Cs). The additional three bonds in (II) and (III) are the result of inter-metal bridging through the water ligands. Two-dimensional coordination polymeric structures with the layers lying parallel to (100) are generated through a number of bridging bonds involving the water mol-ecules (including hydrogen-bonding inter-actions), as well as through the arsanilate O atoms. These layers are linked across [100] through amine N-H⋯O hydrogen bonds to arsonate and water O-atom acceptors, giving overall three-dimensional network structures.

The coordination complex structures and hydrogen bonding in the three-dimensional alkaline earth metal salts (Mg, Ca, Sr and Ba) of (4-aminophenyl)arsonic acid.

(4-Aminophenyl)arsonic acid (p-arsanilic acid) is used as an antihelminth in veterinary applications and was earlier used in the monosodium salt dihydrate form as the antisyphilitic drug atoxyl. Examples of complexes with this acid are rare. The structures of the alkaline earth metal (Mg, Ca, Sr and Ba) complexes with (4-aminophenyl)arsonic acid (p-arsanilic acid) have been determined, viz. hexaaquamagnesium bis[hydrogen (4-aminophenyl)arsonate] tetrahydrate, [Mg(H2O)6](C6H7AsNO3)·4H2O, (I), catena-poly[[[diaquacalcium]-bis[µ2-hydrogen (4-aminophenyl)arsonato-κ2O:O']-[diaquacalcium]-bis[µ2-hydrogen (4-aminophenyl)arsonato-κ2O:O]] dihydrate], {[Ca(C6H7AsNO3)2(H2O)2]·2H2O}n, (II), catena-poly[[triaquastrontium]-bis[µ2-hydrogen (4-aminophenyl)arsonato-κ2O:O']], [Sr(C6H7AsNO3)2(H2O)3]n, (III), and catena-poly[[triaquabarium]-bis[µ2-hydrogen (4-aminophenyl)arsonato-κ2O:O']], [Ba(C6H7AsNO3)2(H2O)3]n, (IV). In the structure of magnesium salt (I), the centrosymmetric octahedral [Mg(H2O)6]2+ cation, the two hydrogen p-arsanilate anions and the four water molecules of solvation form a three-dimensional network structure through inter-species O-H and N-H hydrogen-bonding interactions with water and arsonate O-atom and amine N-atom acceptors. In one-dimensional coordination polymer (II), the distorted octahedral CaO6 coordination polyhedron comprises two trans-related water molecules and four arsonate O-atom donors from bridging hydrogen arsanilate ligands. One bridging extension is four-membered via a single O atom and the other is eight-membered via O:O'-bridging, both across inversion centres, giving a chain coordination polymer extending along the [100] direction. Extensive hydrogen-bonding involving O-H...O, O-H...N and N-H...O interactions gives an overall three-dimensional structure. The structures of the polymeric Sr and Ba complexes (III) and (IV), respectively, are isotypic and are based on irregular MO7 coordination polyhedra about the M2+ centres, which lie on twofold rotation axes along with one of the coordinated water molecules. The coordination centres are linked through inversion-related arsonate O:O'-bridges, giving eight-membered ring motifs and forming coordination polymeric chains extending along the [100] direction. Inter-chain N-H...O and O-H...O hydrogen-bonding interactions extend the structures into three dimensions and the crystal packing includes π-π ring interactions [minimum ring centroid separations = 3.4666 (17) Šfor (III) and 3.4855 (8) Šfor (IV)].

Crystal structure and hydrogen bonding in the water-stabilized proton-transfer salt brucinium 4-amino-phenyl-arsonate tetra-hydrate.

In the structure of the brucinium salt of 4-amino-phenyl-arsonic acid (p-arsanilic acid), systematically 2,3-dimeth-oxy-10-oxostrychnidinium 4-amino-phenyl-ar-son-ate tetra-hydrate, (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O, the brucinium cations form the characteristic undulating and overlapping head-to-tail layered brucine substructures packed along [010]. The arsanilate anions and the water mol-ecules of solvation are accommodated between the layers and are linked to them through a primary cation N-H⋯O(anion) hydrogen bond, as well as through water O-H⋯O hydrogen bonds to brucinium and arsanilate ions as well as bridging water O-atom acceptors, giving an overall three-dimensional network structure.

Crystal structures and hydrogen bonding in the proton-transfer salts of nicotine with 3,5-di-nitro-salicylic acid and 5-sulfosalicylic acid.

The structures of the 1:1 anhydrous salts of nicotine (NIC) with 3,5-di-nitro-salicylic acid (DNSA) and 5-sulfosalicylic acid (5-SSA), namely (1R,2S)-1-methyl-2-(pyridin-3-yl)-1H-pyrrolidin-1-ium 2-carb-oxy-4,6-di-nitro-phenolate, C10H15N2 (+)·C7H3N2O7 (-), (I), and (1R,2S)-1-methyl-2-(pyridin-3-yl)-1H-pyrrolidin-1-ium 3-carb-oxy-4-hy-droxy-benzene-sulfonate, C10H15N2 (+)·C7H5O6S(-), (II), are reported. The asymmetric units of both (I) and (II) comprise two independent nicotinium cations (C and D) and either two DNSA or two 5-SSA anions (A and B), respectively. One of the DNSA anions shows a 25% rotational disorder in the benzene ring system. In the crystal of (I), inter-unit pyrrolidinium N-H⋯Npyridine hydrogen bonds generate zigzag NIC cation chains which extend along a, while the DNSA anions are not involved in any formal inter-species hydrogen bonding but instead form π-π-associated stacks which are parallel to the NIC cation chains along a [ring-centroid separation = 3.857 (2) Å]. Weak C-H⋯O inter-actions between chain substructures give an overall three-dimensional structure. In the crystal of (II), A and B anions form independent zigzag chains with C and D cations, respectively, through carb-oxy-lic acid O-H⋯Npyridine hydrogen bonds. These chains, which extend along b, are pseudocentrosymmetrically related and give π-π inter-actions between the benzene rings of anions A and B and the pyridine rings of the NIC cations C and D, respectively [ring centroid separations = 3.6422 (19) and 3.7117 (19) Å]. Also present are weak C-H⋯O hydrogen-bonding inter-actions between the chains, giving an overall three-dimensional structure.

The three-dimensional hydrogen-bonded structures in the ammonium and sodium salt hydrates of 4-aminophenylarsonic acid.

The structures of two hydrated salts of 4-aminophenylarsonic acid (p-arsanilic acid), namely ammonium 4-aminophenylarsonate monohydrate, NH4(+)·C6H7AsNO3(-)·H2O, (I), and the one-dimensional coordination polymer catena-poly[[(4-aminophenylarsonato-κO)diaquasodium]-µ-aqua], [Na(C6H7AsNO3)(H2O)3]n, (II), have been determined. In the structure of the ammonium salt, (I), the ammonium cations, arsonate anions and water molecules interact through inter-species N-H...O and arsonate and water O-H...O hydrogen bonds, giving the common two-dimensional layers lying parallel to (010). These layers are extended into three dimensions through bridging hydrogen-bonding interactions involving the para-amine group acting both as a donor and an acceptor. In the structure of the sodium salt, (II), the Na(+) cation is coordinated by five O-atom donors, one from a single monodentate arsonate ligand, two from monodentate water molecules and two from bridging water molecules, giving a very distorted square-pyramidal coordination environment. The water bridges generate one-dimensional chains extending along c and extensive interchain O-H...O and N-H...O hydrogen-bonding interactions link these chains, giving an overall three-dimensional structure. The two structures reported here are the first reported examples of salts of p-arsanilic acid.

4-(4-Amino-phenyl-sulfon-yl)anilinium toluene-4-sulfonate.

In the title p-toluene-sulfonate salt of the drug dapsone, C12H13N2O2S(+)·C7H7O3S(-), the dihedral angle between the two aromatic rings of the dapsone monocation is 70.19 (17)° and those between these rings and that of the p-toluene-sulfonate anion are 72.34 (17) and 46.43 (17)°. All amine and aminium H atoms are involved in inter-molecular N-H⋯O hydrogen-bonding associations with sulfonyl O-atom acceptors as well as one of the sulfone O atoms, giving a three-dimensional structure.

Investigation of the l-phenylacetylcarbinol process to substituted benzaldehydes of interest.

The large scale industrial manufacture of the nasal decongestant pseudoephedrine is typically carried out by the reductive amination of l-phenylacetylcarbinol (l-PAC), which in turn is produced via the biotransformation of benzaldehyde using yeast. In recent years there has been increasing legislative control of the supply of pseudoephedrine due to it being diverted for the clandestine production of methylamphetamine and there is some evidence that a number of clandestine drug laboratory chemists have considered the application of the l-PAC process to manufacture their own pseudoephedrine. This work examined the use of a number of substituted benzaldehydes for the manufacture of the corresponding substituted l-PAC analogue followed by reductive amination to the corresponding substituted pseudoephedrine/ephedrine analogues. These substituted pseudoephedrine/ephedrine analogues were either reduced or oxidised to determine the feasibility of producing the corresponding methylamphetamine or methcathinone analogues. As a result, the l-PAC process was identified as a viable route for synthesis of substituted methylamphetamines and methcathinones.

4-Meth-oxy-anilinium 2-carb-oxy-4,5-di-chloro-benzoate.

In the title salt C7H10NO(+)·C8H3Cl2O4 (-) the benzene rings of the cation and anion are essentially parallel [inter-ring dihedral angle 4.8 (2)°]. In the anion the carb-oxy-lic acid and carboxyl-ate groups make dihedral angles of 19.0 (2) and 79.5 (2)°, respectively, with the benzene ring. Aminium N-H⋯O, carb-oxy-lic acid O-H⋯O and weak aromatic C-H⋯O hydrogen-bonding associations with carboxyl O-atom acceptors together with cation-anion π-π ring inter-actions [minimum ring centroid separation = 3.734 (3) Å] give rise to a sheet structure lying parallel to (001).

Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the dicarboxylic oxalic and adipic acid homologues.

The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O(+)·C2HO4(-)·2H2O, (I), and with adipic acid, bis(4-carbamoylpiperidinium) adipate dihydrate, 2C6H13N2O(+)·C6H8O4(2-)·2H2O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carboxylic acid O-H···O(carboxyl) hydrogen-bonding interactions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N-H···O hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N-H···O(carboxyl) hydrogen bonds, generating cyclic R4(3)(10) and R3(2)(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water molecule. In the crystal structure, the two inversion-related cations are interlinked through the two water molecules, which act as acceptors in dual amide N-H···O(water) hydrogen bonds, to give a cyclic R4(2)(8) association which is conjoined with an R4(4)(12) motif. Further N-H···O(water), water O-H···O(amide) and piperidinium N-H···O(carboxyl) hydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water molecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide-amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

Hydrogen bonding in two ammonium salts of 5-sulfosalicylic acid: ammonium 3-carboxy-4-hydroxybenzenesulfonate monohydrate and triammonium 3-carboxy-4-hydroxybenzenesulfonate 3-carboxylato-4-hydroxybenzenesulfonate.

The structures of two ammonium salts of 3-carboxy-4-hydroxybenzenesulfonic acid (5-sulfosalicylic acid, 5-SSA) have been determined at 200 K. In the 1:1 hydrated salt, ammonium 3-carboxy-4-hydroxybenzenesulfonate monohydrate, NH4(+)·C7H5O6S(-)·H2O, (I), the 5-SSA(-) monoanions give two types of head-to-tail laterally linked cyclic hydrogen-bonding associations, both with graph-set R4(4)(20). The first involves both carboxylic acid O-H···O(water) and water O-H···O(sulfonate) hydrogen bonds at one end, and ammonium N-H···O(sulfonate) and N-H···O(carboxy) hydrogen bonds at the other. The second association is centrosymmetric, with end linkages through water O-H···O(sulfonate) hydrogen bonds. These conjoined units form stacks down c and are extended into a three-dimensional framework structure through N-H···O and water O-H···O hydrogen bonds to sulfonate O-atom acceptors. Anhydrous triammonium 3-carboxy-4-hydroxybenzenesulfonate 3-carboxylato-4-hydroxybenzenesulfonate, 3NH4(+)·C7H4O6S(2-)·C7H5O6S(-), (II), is unusual, having both dianionic 5-SSA(2-) and monoanionic 5-SSA(-) species. These are linked by a carboxylic acid O-H···O hydrogen bond and, together with the three ammonium cations (two on general sites and the third comprising two independent half-cations lying on crystallographic twofold rotation axes), give a pseudo-centrosymmetric asymmetric unit. Cation-anion hydrogen bonding within this layered unit involves a cyclic R3(3)(8) association which, together with extensive peripheral N-H···O hydrogen bonding involving both sulfonate and carboxy/carboxylate acceptors, gives a three-dimensional framework structure. This work further demonstrates the utility of the 5-SSA(-) monoanion for the generation of stable hydrogen-bonded crystalline materials, and provides the structure of a dianionic 5-SSA(2-) species of which there are only a few examples in the crystallographic literature.

Proton-transfer compounds with 4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (sulfamethazine): the structures and hydrogen bonding in the salts with 5-nitrosalicylic acid and picric acid.

The structures of the anhydrous proton-transfer compounds of the sulfa drug sulfamethazine with 5-nitrosalicylic acid and picric acid, namely 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2-hydroxy-5-nitrobenzoate, C12H15N4O2S(+)·C7H4NO4(-), (I), and 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2,4,6-trinitrophenolate, C12H15N4O2S(+)·C6H2N3O7(-), (II), respectively, have been determined. In the asymmetric unit of (I), there are two independent but conformationally similar cation-anion heterodimer pairs which are formed through duplex intermolecular N(+)-H···O(carboxylate) and N-H···O(carboxylate) hydrogen-bond pairs, giving a cyclic motif [graph set R2(2)(8)]. These heterodimers form separate and different non-associated substructures through aniline N-H···O hydrogen bonds, one one-dimensional, involving carboxylate O-atom acceptors, the other two-dimensional, involving both carboxylate and hydroxy O-atom acceptors. The overall two-dimensional structure is stabilized by π-π interactions between the pyrimidinium ring and the 5-nitrosalicylate ring in both heterodimers [minimum ring-centroid separation = 3.4580 (8) Å]. For picrate (II), the cation-anion interaction involves a slightly asymmetric chelating N-H···O R2(1)(6) hydrogen-bonding association with the phenolate O atom, together with peripheral conjoint R1(2)(6) interactions between the same N-H groups and O atoms of the ortho-related nitro groups. An inter-unit amine N-H···O(sulfone) hydrogen bond gives one-dimensional chains which extend along a and inter-associate through π-π interactions between the pyrimidinium rings [centroid-centroid separation = 3.4752 (9) Å]. The two structures reported here now bring to a total of four the crystallographically characterized examples of proton-transfer salts of sulfamethazine with strong organic acids.

2-(4-Amino-benzene-sulfonamido)-4,6-dimethyl-pyrimidin-1-ium 2-carb-oxy-4,6-dinitro-phenolate.

In the structure of the phenolate salt of the sulfa drug sulfamethazine with 3,5-dinitro-salicylic acid, C12H15N4O2S(+)·C7H3N2O7 (-), the dihedral angle between the pyrimidine and benzene rings of the cation is 59.70 (17)°. In the crystal, cation-anion hydrogen-bonding inter-actions involving pyrim-idine-carb-oxy N(+)-H⋯O and amine-carb-oxy N-H⋯O pairs give a cyclic R 2 (2)(8) motif while secondary N-H⋯O hydrogen bonds between the aniline group and both sulfone and nitro O-atom acceptors give a two-dimensional structure extending in (001).

4-(4-Nitro-benz-yl)pyridinium 3-carb-oxy-4-hy-droxy-benzene-sulfonate.

In the title salt, C(12)H(11)N(2)O(2) (+)·C(7)H(5)O(6)S(-), the dihedral angle between the benzene and pyridine rings in the 4-(4-nitro-benz-yl)pyridinium cation is 82.7 (2)°. Within the anion there is an intramolecular hydroxy-O-H⋯O(carboxylic acid) bond. In the crystal, the cation forms a single N(+)-H⋯O(sulfonate) hydrogen bond with the anion. These cation-anion pairs inter-act through duplex anion carb-oxy-lic acid O-H⋯O(sulfonate) hydrogen bonds, giving a centrosymmetric cyclic association [graph set R(2) (2)(16)]. The crystals studied were non-merohedrally twinned.

4-Amino-N-(4,6-dimethyl-pyrimidin-2-yl)benzene-sulfonamide-2-nitro-benzoic acid (1/1).

In the asymmetric unit of the title co-crystal, C(12)H(14)N(4)O(2)S·C(7)H(5)NO(4), the sulfamethazine and 2-nitro-benzoic acid mol-ecules form a heterodimer through inter-molecular amide-carb-oxy-lic acid N-H⋯O and carb-oxy-lic acid-pyrimidine O-H⋯N hydrogen-bond pairs, giving a cyclic motif [graph set R(2) (2)(8)]. The dihedral angle between the two aromatic ring systems in the sulfamethazine mol-ecule is 88.96 (18)° and the nitro group of the acid is 50% rotationally disordered. Secondary aniline N-H⋯O(sulfone) hydrogen-bonding associations give a two-dimensional structure lying parallel to the ab plane.

Hydrogen bonding in cyclic imides and amide carboxylic acid derivatives from the facile reaction of cis-cyclohexane-1,2-carboxylic anhydride with o- and p-anisidine and m- and p-aminobenzoic acids.

The structures of the open-chain amide carboxylic acid rac-cis-2-[(2-methoxyphenyl)carbamoyl]cyclohexane-1-carboxylic acid, C(15)H(19)NO(4), (I), and the cyclic imides rac-cis-2-(4-methoxyphenyl)-3a,4,5,6,7,7a-hexahydroisoindole-1,3-dione, C(15)H(17)NO(3), (II), chiral cis-3-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)benzoic acid, C(15)H(15)NO(4), (III), and rac-cis-4-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)benzoic acid monohydrate, C(15)H(15)NO(4)·H(2)O, (IV), are reported. In the amide acid (I), the phenylcarbamoyl group is essentially planar [maximum deviation from the least-squares plane = 0.060 (1) Å for the amide O atom] and the molecules form discrete centrosymmetric dimers through intermolecular cyclic carboxy-carboxy O-H···O hydrogen-bonding interactions [graph-set notation R(2)(2)(8)]. The cyclic imides (II)-(IV) are conformationally similar, with comparable benzene ring rotations about the imide N-C(ar) bond [dihedral angles between the benzene and isoindole rings = 51.55 (7)° in (II), 59.22 (12)° in (III) and 51.99 (14)° in (IV)]. Unlike (II), in which only weak intermolecular C-H···O(imide) hydrogen bonding is present, the crystal packing of imides (III) and (IV) shows strong intermolecular carboxylic acid O-H···O hydrogen-bonding associations. With (III), these involve imide O-atom acceptors, giving one-dimensional zigzag chains [graph-set C(9)], while with the monohydrate (IV), the hydrogen bond involves the partially disordered water molecule which also bridges molecules through both imide and carboxy O-atom acceptors in a cyclic R(4)(4)(12) association, giving a two-dimensional sheet structure. The structures reported here expand the structural database for compounds of this series formed from the facile reaction of cis-cyclohexane-1,2-dicarboxylic anhydride with substituted anilines, in which there is a much larger incidence of cyclic imides compared to amide carboxylic acids.

Cyclic imides and an open-chain amide carboxylic acid from the facile reaction of cis-cyclohexane-1,2-carboxylic anhydride with the isomeric monofluoroanilines.

The structures of the cyclic imides cis-2-(2-fluorophenyl)-3a,4,5,6,7,7a-hexahydroisoindole-1,3-dione, C(14)H(14)FNO(2), (I), and cis-2-(4-fluorophenyl)-3a,4,5,6,7,7a-hexahydroisoindoline-1,3-dione, C(14)H(14)FNO(2), (III), and the open-chain amide acid rac-cis-2-[(3-fluorophenyl)carbamoyl]cyclohexane-1-carboxylic acid, C(14)H(16)FNO(3), (II), are reported. Cyclic imides (I) and (III) are conformationally similar, with comparable ring rotations about the imide N-C(ar) bond [the dihedral angles between the benzene ring and the five-membered isoindole ring are 55.40 (8)° for (I) and 51.83 (7)° for (III)]. There are no formal intermolecular hydrogen bonds involved in the crystal packing of either (I) or (III). With the acid (II), in which the meta-related F-atom substituent is rotationally disordered (0.784:0.216), the amide group lies slightly out of the benzene plane [the interplanar dihedral angle is 39.7 (1)°]. Intermolecular amide-carboxyl N-H···O hydrogen-bonding interactions between centrosymmetrically related molecules form stacks extending down b, and these are linked across c by carboxyl-amide O-H···O hydrogen bonds, giving two-dimensional layered structures which lie in the (011) plane. The structures reported here represent examples of compounds analogous to the phthalimides or phthalanilic acids and have little precedence in the crystallographic literature.

4-Amino-N-(4,6-dimethyl-pyrimidin-2-yl)-benzene-sulfonamide-4-nitro-benzoic acid (1/1).

In the asymmetric unit of the title co-crystal, C(7)H(5)NO(4)·C(12)H(14)N(4)O(2)S, there are two independent but conformationally similar heterodimers, which are formed through inter-molecular N-H⋯O(carb-oxy) and carbox-yl-pyrimidine O-H⋯N hydrogen-bond pairs, giving a cyclic motif [graph set R(2) (2)(8)]. The dihedral angles between the rings in the sulfonamide molecules are 78.77 (8) and 82.33 (9)° while the dihedral angles between the ring and the CO(2)H group in the acids are 2.19 (9) and 7.02 (10)°. A two-dimensional structure parallel to the ab plane is generated from the heterodimer units through hydrogen-bonding associations between NH(2) and sulfone groups. Between neighbouring two-dimensional arrays there are two types of aromatic π-π stacking inter-actions involving either one of the pyrimidine rings and a 4-nitro-benzoic acid mol-ecule [minimum ring centroid separation = 3.5886 (9) Å] or two acid mol-ecules [minimum ring centroid separation = 3.7236 (10) Å].

Bis(benzyl-aminium) 4,5-dichloro-benzene-1,2-dicarboxyl-ate monohydrate.

In the structure of the title salt, 2C(7)H(10)N(+)·C(8)H(2)Cl(2)O(4) (2-)·H(2)O, the two benzyl-aminium anions have different conformations, one being essentially planar and the other having the side chain rotated out of the benzene plane [minimum ring to side-chain C-C-C-N torsion angles = -3.6 (6) and 50.1 (5)°, respectively]. In the 4,5-dichloro-phthalate dianion, the carboxyl-ate groups make dihedral angles of 23.0 (2) and 76.5 (2)° with the benzene ring. In the crystal, aminium N-H⋯O and water O-H⋯O hydrogen-bonding associations with carboxyl-ate O-atom acceptors give a two-dimensional duplex sheet structure which extends along the (011) plane. Weak π-π inter-actions are also present between the benzene ring of the dianion and one of the cation rings [minimum ring centroid separation = 2.749 (3) Å].