Cyclic Centrosymmetric Dimers Research Articles

A hydrogen-bonded dimer in 6-(4-bromophenyl)-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazolo[3,4-b]pyridine and a chain of rings built from N—H...N and C—H...π(pyridine) hydrogen bonds in 3-(4-nitrophenyl)-4-phenyl-1H-pyrazolo[3,4-b]pyridine

In 6-(4-bromophenyl)-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazolo[3,4-b]pyridine, C(19)H(16)BrN(3), the reduced pyridine ring adopts a conformation that is close to a screw-boat form. Molecules are linked by pairs of symmetry-related C-H...pi(arene) hydrogen bonds into cyclic centrosymmetric dimers. Molecules of 3-(4-nitrophenyl)-4-phenyl-1H-pyrazolo[3,4-b]pyridine, C(18)H(12)N(4)O(2), are linked into centrosymmetric R(2)(2)(8) dimers by pairs of symmetry-related N-H...N hydrogen bonds, and these dimers are linked by pairs of C-H...pi(pyridine) hydrogen bonds to form a chain of edge-fused rings, or a molecular ladder, along [100]. The molecular aggregation in this compound is completed by two weak C-H...O hydrogen bonds, one of which links the chains along [100] into sheets.

N-(4-Methoxyphenyl)-tert-butanesulfinamide

In the title compound, C11H17NO2S, the mol­ecules inter­act head-to-tail through N—H⋯OS hydrogen bonds, giving discrete centrosymmetric cyclic dimers. The N—Car­yl bond length [1.4225 (14) Å] is inter­mediate between that in N-phenyl-tert-butane­sulfinamide [1.4083 (12) Å] and the N—Calk­yl bond lengths in N-alkyl­alkanesulfinamides (1.470–1.530 Å), suggesting weaker delocalization of electrons over the N atom and the aromatic ring due to the presence of the 4-meth­oxy group.

Sterically shielded pyramidal amino groups in two 4,4′-(arylmethylene)bis(6-allyl-3-chloro-2-methylaniline) derivatives

4,4'-(Phenylmethylene)bis(6-allyl-3-chloro-2-methylaniline), C(27)H(28)Cl(2)N(2), (I), and 4,4'-(2-thienylmethylene)bis(6-allyl-3-chloro-2-methylaniline), C(25)H(26)Cl(2)N(2)S, (II), adopt similar molecular conformations, although the thienyl group in (II) exhibits orientational disorder over two sets of sites with occupancies of 0.614 (3) and 0.386 (3). The amino groups in both compounds are pyramidal. A single N-H...N hydrogen bond links the molecules of (I) into cyclic centrosymmetric dimers. Molecules of (II) are linked by an ordered C-H...pi(arene) hydrogen bond to form cyclic centrosymmetric dimers, and these dimers are linked into statistically interrupted chains by a second C-H...pi(arene) hydrogen bond involving a donor in the minor component of the disordered thienyl unit.

Different hydrogen-bonded structures in three 2-thienyl-substituted tetrahydro-1,4-epoxy-1-benzazepines

The molecules of (2RS,4SR)-2-exo-(5-bromo-2-thienyl)-7-chloro-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(14)H(11)BrClNOS, (I), are linked into cyclic centrosymmetric dimers by C-H...pi(thienyl) hydrogen bonds. Each such dimer makes rather short Br...Br contacts with two other dimers. In (2RS,4SR)-2-exo-(5-methyl-2-thienyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(15)H(15)NOS, (II), a combination of C-H...O and C-H...pi(thienyl) hydrogen bonds links the molecules into chains of rings. A more complex chain of rings is formed in (2RS,4SR)-7-chloro-2-exo-(5-methyl-2-thienyl)-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C(15)H(14)ClNOS, (III), built from a combination of two independent C-H...O hydrogen bonds, one C-H...pi(arene) hydrogen bond and one C-H...pi(thienyl) hydrogen bond.

3,3'-(p-Phenyl-ene)bis-(3,4-dihydro-2H-1,3-benzoxazine).

Mol­ecules of the title compound, C22H20N2O2, are situated on crystallographic centres of symmetry. The oxazinane ring adopts a sofa conformation. Mol­ecules are linked into cyclic centrosymmetric dimers via C—H⋯O hydrogen bonds with the motif R 2 2(6). In addition to the C—H⋯O inter­actions, the crystal structure is also stabilized by C—H⋯π inter­actions.

Different hydrogen-bonded structures in the isomeric solvates 2-amino-6-anilino-4-methoxy-5-[(E)-4-nitrobenzylideneamino]pyrimidine dimethyl sulfoxide solvate and 2-amino-6-[methyl(phenyl)amino]-5-[(E)-4-nitrobenzylideneamino]pyrimidin-4(3H)-one dimethyl sulfoxide solvate

The title solvates, (I) and (II), both C(18)H(16)N(6)O(3).C(2)H(6)OS, are isomeric. The conformations adopted by the 6-substituent are significantly different, with the 6-aminophenyl unit remote from the nitrophenyl ring in methoxypyrimidine (I) but adjacent to it in pyrimidinone (II). Pairs of pyrimidine molecules in (I) are linked by N-H...N hydrogen bonds to form cyclic centrosymmetric dimers from which the dimethyl sulfoxide molecules are pendent, while in (II) a combination of three independent N-H...O hydrogen bonds links the components into a chain containing both R(2)(2)(8) and R(4)(2)(8) rings, in which the dimethyl sulfoxide component acts as a double acceptor of hydrogen bonds. The significance of this study lies in its observation of different conformations for the pyrimidine components in (I) and (II), and different hydrogen-bonded structures, apparently dominated by the different roles adopted by the dimethyl sulfoxide components.

N-(4-Chlorophenyl)-4-(2-oxocyclopentyl)butyramide

In the title compound, C15H18ClNO2, the amide group is coplanar with the chloro­phenyl group, making a dihedral angle of 1.71 (12)°. The cyclo­penta­none ring adopts a twist conformation. A weak intra­molecular C—H⋯O hydrogen bond is observed. Mol­ecules are linked into cyclic centrosymmetric dimers by paired N—H⋯O hydrogen bonds.

3-[2-(9-Ethyl-9H-carbazol-3-yl)-6-methyl-3-quinolyl]propan-1-ol

In the title compound, C27H26N2O, the mean planes through the carbazole and quinoline ring systems form a dihedral angle of 67.23 (5)°. Mol­ecules are linked into cyclic centrosymmetric dimers by O—H⋯N hydrogen bonds, and C—H⋯π inter­actions with the pyridine ring of the quinoline ring system as an acceptor. The dimers are linked through C—H⋯O hydrogen bonds.

Synthesis and crystal structure of the salt of the protonated oxythiamine cation with a platinum(IV) mixed-halide anion [H2OT][Pt(Cl/Br)6

The interaction of oxythiamine bromide hydrobromide with H2PtCl6 in a hydrochloric acid solution gives the salt of protonated oxythiamine (oxythiamine is the 4-methyl-3-[(2′-methyl-4′-oxo-3′,4′-dihydropyrimidinyl-5′)methyl]-5-(2-hydroxyethyl)thiazolium cation,C12H16N3O2S+) with a platinum(IV) mixed-ligand anion, (C12H17Br2.32Cl3.68N3O2PtS) (I). The crystals of salt I are monoclinic: a = 12.888(3), b = 10.835(2), c =15.898(4) A, β = 113.03(2)°, Z = 4, space group P21/c. They are built of the [H2OT]2+ cations and [Pt(Cl/Br)6]2− anions joined by hydrogen bonds and electrostatic and π-π stacking interactions. In the cation, the planar thiazolium and pyrimidine rings are bound through the methylene bridge, form a dihedral angle of 90.0°, and exist in the F conformation. The cations are combined into centrosymmetric cyclic dimers flanked on both sides by centrosymmetrically arranged octahedral anions to form short contacts.

Catena-Poly[[bis[μ-2-(3-pyridyl)-1H-benzimidazole]-κ2N2:N3;κ2N3:N2-disilver(I)]-μ-2,5-dicarboxybenzene-1,4-dicarboxylato-κ2O2:O5

The title coordination polymer, [Ag2(C10H4O8)(C12H9N3)2]n, was prepared by a hydro­thermal method. The AgI atom exists in a strongly distorted trigonal coordination environment. Two AgI ions related by an inversion centre are coordinated by two 2-(3-pyrid­yl)benzimidazole ligands, forming a centrosymmetric cyclic dimer. The bridging bidentate 2,5-dicarboxy­benzene-1,4-dicarboxyl­ate ligand is also located on an inversion centre and connects the binuclear units, generating a one-dimensional polymer. The almost-planar conformation of this ligand allows it to form a strong intra­molecular O—H⋯O hydrogen bond. Finally, inter­molecular N—H⋯O hydrogen bonds aggregate the chains into a three-dimensional framework.

Patterns of hydrogen bonding in mono- and di-substituted N-arylpyrazinecarboxamides

The molecular and supramolecular structures of 18 N-arylpyrazinecarboxamides, Ar NHCO(C(4)H(3)N(2)), have been determined, including the stoichiometric monohydrate of N-(3-methoxyphenyl)pyrazinecarboxamide, and two polymorphs of N-(4-fluorophenyl)pyrazinecarboxamide having Z' values of 1 and 4, respectively. The aryl groups were selected to include the geometric isomers for a compact range of substituents, namely methyl, trifluoromethyl, fluoro, chloro, methoxy and nitro groups, which exhibit markedly varied electronic properties and markedly varied behaviour as hydrogen-bond donors and acceptors. However, not all isomers in each group could be structurally investigated. A small number of derivatives containing disubstituted aryl groups have also been included in this study. The crystal structures of the solvent-free carboxamides reported here exhibit a wide range of direction-specific intermolecular forces, including N-H...N, N-H...O, C-H...N and C-H...O hydrogen bonds, and pi...pi stacking interactions, while the structure of N-(3-methoxyphenyl)pyrazinecarboxamide monohydrate also contains O-H...N and O-H...O hydrogen bonds. The resulting supramolecular structures can be zero-, one- or two-dimensional, although no three-dimensional supramolecular aggregation has been observed. In the finite, zero-dimensional structures, pairs of molecules are linked by hydrogen bonds to form cyclic centrosymmetric dimers. The one-dimensional structures include chains formed by the pi-stacking of otherwise isolated molecules, simple chains generated by either C-H...O or C-H...N hydrogen bonds, and hydrogen-bonded chains of rings. The two-dimensional structures include examples of both pi-stacked hydrogen-bonded chains and hydrogen-bonded sheets.

Bis[μ-2-(3-pyridyl)benzimidazole]bis[bis(3,5-dicarboxybenzoato)silver(I)

In the binuclear title complex, [Ag2(C9H5O6)2(C12H9N3)2], the two AgI atoms are in a trigonal planar environment formed by two N atoms from two 2-(3-pyrid­yl)benzimidazole ligands and one O atom from a 3,5-dicarboxy­benzoate ligand, forming a centrosymmetric cyclic dimer. Inter­molecular N—H⋯O and O—H⋯O hydrogen-bonding inter­actions aggregate the binuclear units into a three-dimensional framework.

Bis[μ-2-(3-pyridyl)-1H-benzimidazole-κ2 N:N′]disilver(I) dinitrate

The title compound, [Ag2(C12H9N3)2](NO3)2, was prepared under hydrothermal conditions. The structure consists of binuclear complex cations and nitrate anions. The two AgI atoms, each in a geometry somewhat distorted from linear, are bridged by two 2-(3-pyridyl)benzimidazole ligands via pyridyl and imidazole N atoms, forming a centrosymmetric cyclic dimer. A three-dimensional network is constructed via N—H...O hydrogen bonds and weak Ag...O interactions [Ag...O = 2.686 (13)–2.847 (7) Å], as well as by offset π–π interactions between the pyridyl and imidazolyl rings with a nearest atom-to-atom distance of 3.40 (2) Å and a centroid-to-centroid distance of 4.06 (3) Å.

Dimethyl(1,10-phenanthroline)bis(2,3,4,5-tetrafluorobenzoato)tin(IV)

The title compound, [Sn(CH3)2(C7HF4O2)2(C12H8N2)], was synthesized by the reaction of dimethyltin(IV) dichloride and disodium 2,3,4,5-tetrafluorobenzoate in the presence of 1,10-phenanthroline. In the complex, the SnIV ion is coordinated by three O atoms of two tetrafluorobenzoate ligands, two N atoms of a 1,10-phenanthroline ligand and two methyl groups in a distorted pentagonal–bipyramidal coordination. The axial positions are occupied by the methyl groups. In the crystal structure, C—H...F and C—H...O hydrogen bonds link the molecules into cyclic centrosymmetric dimers.

Bis(μ-4-carboxy-2-sulfonatobenzoato)bis[aqua(2,2′-bipyridyl)manganese(II)

In the title compound, [Mn(2)(C(8)H(4)O(7)S)(2)(C(10)H(8)N(2))(2)(H(2)O)(2)], pairs of hexacoordinated manganese(II) centres are bridged by 2-sulfonatoterephthalate(2-) anions to form cyclic centrosymmetric dimers, which are linked into sheets by O-H...O hydrogen bonds.

8-tert-Butyl-7,10-diphenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline

In the title compound, C30H27N3, the non-aromatic carbocyclic ring adopts an almost perfect screw-boat conformation; the mol­ecules are linked into cyclic centrosymmetric dimers by pairs of C—H⋯π(pyrid­yl) hydrogen bonds.

Supramolecular aggregation in three 4-aryl-6-(1H-indol-3-yl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles

Both 6-(1H-indol-3-yl)-3-methyl-4-(4-methylphenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile and 6-(1H-indol-3-yl)-3-methyl-4-(4-methoxyphenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile crystallize from dimethylformamide solutions as stoichiometric 1:1 solvates, viz. C(29)H(21)N(5).C(3)H(7)NO, (I), and C(29)H(21)N(5)O.C(3)H(7)NO, (II), respectively; however, 6-(1H-indol-3-yl)-3-methyl-1-phenyl-4-(3,4,5-trimethoxyphenyl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile, C(31)H(25)N(5)O(3), (III), crystallizes in the unsolvated form. The heterocyclic components of (I) are linked by C-H...pi(arene) hydrogen bonds to form cyclic centrosymmetric dimers, from which the solvent molecules are pendent, linked by N-H...O hydrogen bonds. In (II), the heterocyclic components are linked by a combination of C-H...N and C-H...pi(arene) hydrogen bonds into chains containing two types of centrosymmetric ring, and the pendent solvent molecules are linked to these chains by N-H...O hydrogen bonds. Molecules of (III) are linked into simple C(12) chains by an N-H...O hydrogen bond, and these chains are weakly linked into pairs by an aromatic pi-pi stacking interaction.

9-(2,5-Dimethoxybenzyl)-9H-carbazole: sheets built from C—H...π and π–π interactions

In the title compound, C21H19NO2, the carbazole ring system is planar to within 0.032 (1) A, and forms a dihedral angle of 74.42 (3)° with the plane of the attached benzene ring. Inversion-related mol­ecules are linked by C—H⋯π hydrogen bonds into cyclic centrosymmetric dimers, which are inter­linked into a chain along the c axis by π–π stacking inter­actions. Adjacent glide-related chains are inter­linked via C—H⋯π inter­actions into a sheet parallel to the bc plane.

Simple chains in methyl 3,5-dinitrobenzoate, isolated molecules in isopropyl 3,5-dinitrobenzoate, and a three-dimensional framework containing double and sextuple helices in benzyl 3,5-dinitrobenzoate, all at 120 K

Molecules of methyl 3,5-dinitrobenzoate, C8H6N2O6, are linked into C7 chains by a single nearly linear C-H...O hydrogen bond, but there are no direction-specific interactions in the structure of isopropyl 3,5-dinitrobenzoate, C10H10N2O6. In benzyl 3,5-dinitrobenzoate, C14H10N2O6, the molecules are linked by four independent C-H...O hydrogen bonds into a complex three-dimensional framework structure, in which it is possible to identify simple substructures in the form of cyclic centrosymmetric dimers, double helices and sextuple helices.

Effect of substitution on the dimensionality of supramolecular aggregation in dihydrobenzopyrazoloquinolines

Molecules of 8-methyl-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C21H17N3, (I), are linked into cyclic centrosymmetric dimers by means of paired C-H...N hydrogen bonds. In each of 8-methyl-7,10-diphenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C27H21N3, (II), and 8-methyl-7-(4-methylphenyl)-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C28H23N3, (III), the molecules are linked by C-H...pi(arene) hydrogen bonds into sheets, although the detailed construction of the sheets is entirely different in (II) and (III). The molecules of 7-(4-methoxyphenyl)-8-methyl-10-phenyl-6,10-dihydro-5H-benzo[h]pyrazolo[3,4-b]quinoline, C28H23N3O, (IV), are linked into a complex three-dimensional framework structure by a combination of C-H...N, C-H...O and three independent C-H...pi(arene) hydrogen bonds.