Hydrogen-Bonding in the Structures of the Hydrated Proton-Transfer Compounds of Isonipecotamide with the Isomeric Indole-2- and Indole-3-Carboxylic Acids

Abstract  

The structures of two hydrated proton-transfer compounds of 4-piperidinecarboxamide (isonipecotamide) with the isomeric heteroaromatic carboxylic acids indole-2-carboxylic acid and indole-3-carboxylic acid, namely 4-carbamoylpiperidinium indole-2-carboxylate dihydrate (1) and 4-carbamoylpiperidinium indole-3-carboxylate hemihydrate (2) have been determined at 200 K. Crystals of both 1 and 2 are monoclinic, space groups P2₁/c and P2/c, respectively with Z = 4 in cells having dimensions a = 10.6811(4), b = 12.2017(4), c = 12.5456(5) ?, β = 96.000(4)° (1) and a = 15.5140(4), b = 10.2908(3), c = 9.7047(3) ?, β = 97.060(3)° (2). Hydrogen-bonding in 1 involves a primary cyclic interaction involving complementary cation amide N–H···O(carboxyl) anion and anion hetero N–H···O(amide) cation hydrogen bonds [graph set R₂²(9)]. Secondary associations involving also the water molecules of solvation give a two-dimensional network structure which includes weak water O–H···π interactions. In the three-dimensional hydrogen-bonded structure of 2, there are classic centrosymmetric cyclic head-to-head hydrogen-bonded amide–amide interactions [graph set R₂²(8)] as well as lateral cyclic amide-O linked amide–amide extensions [graph set R₄²(8)]. The anions and the water molecule, which lies on a twofold rotation axis, are involved in secondary extensions.     

Hydrate Stabilization in the Three-Dimensional Hydrogen-Bonded Structure of the Brucinium Compound,Bis(2,3-dimethoxy-10-oxostrychnidinium) Biphenyl-4,4′-disulfonate Hexahydrate

Abstract  

The crystal structure of the 2:1 proton-transfer compound of brucine with biphenyl-4,4 ′ -disulfonate, bis(2,3-dimethoxy-10-oxostrychnidinium) biphenyl-4,4 ′ -disulfonate hexahydrate (1) has been determined at 173 K. Crystals are monoclinic, space group P2₁ with Z = 2 in a cell with a = 8.0314(2), b = 29.3062(9), c = 12.2625(3) ?, β = 101.331(2)°. The crystallographic asymmetric unit comprises two brucinium cations, a biphenyl-4,4 ′ -disulfonate dianion and six water molecules of solvation. The brucinium cations form a variant of the common undulating and overlapping head-to-tail sheet sub-structure. The sulfonate dianions are also linked head-to-tail by hydrogen bonds into parallel zig-zag chains through clusters of six water molecules of which five are inter-associated, featuring conjoint cyclic eight-membered hydrogen-bonded rings [graph sets R ₃³(8) and R ₄³(8)], comprising four of the water molecules and closed by sulfonate O acceptors. These chain structures occupy the cavities between the brucinium cation sheets and are linked to them peripherally through both brucine N⁺–H···O_sulfonate and O_carbonyl···H–O_water to sulfonate O bridging hydrogen bonds, forming an overall three-dimensional framework structure. This structure determination confirms the importance of water in the stabilization of certain brucine compounds which have inherent crystal instability.     

Phenyl‐ring rotational disorder in the two‐dimensional hydrogen‐bonded structure of the 1:1 proton‐transfer salt of the diazo‐dye precursor 4‐(phenyldiazenyl)aniline (aniline yellow) with l‐tartaric acid

In the structure of the 1:1 proton‐transfer compound from the reaction of l ‐tartaric acid with the azo‐dye precursor aniline yellow [4‐(phenyldiazenyl)aniline], namely 4‐(phenyldiazenyl)anilinium (2R,3R)‐3‐carboxy‐2,3‐dihydroxypropanoate, C₁₂H₁₂N₃⁺·C₄H₅O₆⁻, the asymmetric unit contains two independent 4‐(phenyldiazenyl)anilinium cations and two hydrogen l ‐tartrate anions. The structure is unusual in that all four phenyl rings of the two cations have identical rotational disorder with equal occupancy of the conformations. The two hydrogen l ‐tartrate anions form independent but similar chains through head‐to‐tail carboxyl–carboxylate O—H...O hydrogen bonds [graph set C(7)], which are then extended into a two‐dimensional hydrogen‐bonded sheet structure through hydroxy O—H...O hydrogen‐bonded links. The anilinium groups of the 4‐(phenyldiazenyl)anilinium cations are incorporated into the sheets and also provide internal hydrogen‐bonded extensions, while their aromatic tails are layered in the structure without significant association except for weak π–π interactions [minimum ring centroid separation = 3.844 (3) Å]. The hydrogen l ‐tartrate residues of both anions exhibit the common short intramolecular hydroxy–carboxylate O—H...O hydogen bonds. This work provides a solution to the unusual disorder problem inherent in the structure of this salt, as well as giving another example of the utility of the hydrogen tartrate anion in the generation of sheet substructures in molecular assembly processes.     

Hydro­gen bonding in proton‐transfer compounds of 8‐quinolinol (oxine) with aromatic sulfonic acids

The crystal structures of the proton‐transfer compounds of 8‐quinolinol (oxine) with the aromatic sulfonic acids 2‐amino­benzene­sulfonic acid (orthanilic acid) and 8‐hydroxy‐7‐iodo­quinoline‐5‐sulfonic acid (ferron) have been determined. In both 8‐hydroxy­quinolinium 2‐amino­benzene­sulfonate, C₉H₈NO⁺·C₆H₆NO₃S⁻, (I), and 8‐hydroxyquino­linium 8‐hydroxy‐7‐iodo­quinoline‐5‐sulfonate ses­qui­hydrate, C₉H₈NO⁺·C₉H₆INO₄S⁻·1.5H₂O, (II), extensive hydrogen‐bonding interactions, together with significant cation–cation [in (I)] and cation–anion [in (II)] π–π stacking associations, give rise to layered polymer structures.     

Hydrogen bonding in 1:1 proton‐transfer compounds of 5‐sulfosalicylic acid with 4‐X‐substituted anilines (X = F,Cl or Br)

The crystal structures of three proton‐transfer compounds of 5‐sulfosalicylic acid (3‐carboxy‐4‐hydroxy­benzene­sulfonic acid) with 4‐X‐substituted anilines (X = F, Cl and Br), namely 4‐fluoro­anilinium 5‐sulfosalicylate (3‐carboxy‐4‐hydroxybenzenesulfonate) monohydrate, C₆H₇FN⁺·C₇H₅O₆S⁻·H₂O, (I), 4‐chloro­anilinium 5‐sulfosalicylate hemihydrate, C₆H₇ClN⁺·C₇H₅O₆S⁻·0.5H₂O, (II), and 4‐bromo­anilinium 5‐sulfosalicylate monohydrate, C₆H₇BrN⁺·C₇H₅O₆S⁻·H₂O, (III), have been determined. The asymmetric unit in (II) contains two formula units. All three compounds have three‐dimensional hydrogen‐bonded polymeric structures in which both the water molecule and the carboxylic acid group are involved in structure extension. With both (II) and (III), which are structurally similar, the common cyclic (8) dimeric carboxylic acid association is present, whereas in (I), an unusual cyclic (8) association involving all three hetero‐species is found.     

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 R₄⁴(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⁺·C₇H₄O₆S²⁻·C₇H₅O₆S⁻, (II), is unusual, having both dianionic 5‐SSA²⁻ 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 R₃³(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‐SSA²⁻ species of which there are only a few examples in the crystallographic literature.     

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⁺·C₆H₈O₄²⁻·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 R₄³(10) and R₃²(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 R₄²(8) association which is conjoined with an R₄⁴(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.     

A convenient 3-step synthesis of 3-acetamido-6-arylpyridazines directed to novel Y5 receptor antagonist

A 3-step synthesis of 3-acetamido-6-arylpyridazines as potential NPY5 antagonists.