Two polymorphic forms of 2,5‐bis(4‐methoxy­carbonyl­phenyl)‐1,3,4‐oxa­diazo­le

The title compound [systematic name: di­methyl 4,4′‐(1,3,4‐oxa­diazole‐2,5‐diyl)­di­phenyl­enedi­carboxyl­ate], C₁₈H₁₄N₂O₅, crystallizes under similar conditions in two different ortho­rhombic crystalline forms. In both forms, the mol­ecule consists of two equivalent parts. In form 1, these parts are related by a twofold axis of space group Pbcn, and in form 2, by a mirror plane of space group Cmc2₁. The O atom of the oxa­di­azole ring occupies a special position on the twofold axis and on the mirror plane in forms 1 and 2, respectively.     

Tetrakis(2‐amino‐5‐methyl‐1,3,4‐thia­diazo­le‐N3)­chloro­copper(II) chloride monohydrate and tetrakis(2‐amino‐5‐ethyl‐1,3,4‐thia­diazo­le‐N3)­chlorocopper(II) chloride

The structures of the title compounds, [CuCl(C₃H₅N₃S)₄]Cl·H₂O, (I), and [CuCl(C₄H₇N₃S)₄]Cl, (II), comprise square‐pyramidal Cu centres with four N‐bound organic ligands filling the base positions, a Cl atom in the apical position and a Cl^? as a free counter‐ion. The cation and free chloride ion in (II) have fourfold crystallographic symmetry. Hydro­gen‐bonding associations from the 2‐amino H atoms dominate both structures, with the principal acceptors being the chlorides, although in (I), the N4 atoms are also involved. Furthermore, (I) is a hydrate, with the water mol­ecule participating in the hydrogen‐bonding network.     

2,5‐Bis(2‐(diphenylphosphino)phenyl)‐1,3,4‐oxadiazole ligands and their Cu(I) complexes for Sonogashira coupling reaction

Two diphosphane ligands – 2,5‐bis(2‐(diphenylphosphino)‐5‐R)phenyl)‐1,3,4‐oxadiazole ( L1 , R = H, L2 , R = OMe) and their binuclear complexes, L1Cu and L2Cu , were prepared and characterized. The molecular structures of L1Cu and L2Cu , as perchlorate salts, were established by X‐ray crystallography, which showed them to be binuclear complexes with each Cu atom tetrahedrally coordinated by two P atoms and two N atoms. The ligands and their Cu(I) complexes catalyzed Sonogashira coupling reactions of iodobenzene with phenylacetylene in the presence of K₂CO₃ under Pd‐free conditions. Coupling reactions catalyzed by L1 or L2 with Cu(MeCN)₄ClO₄ in situ exhibited better yields than those by the corresponding Cu(I) complexes L1Cu or L2Cu . Detailed studies showed L1 or L2 with Cu(MeCN)₄ClO₄ to be suitable catalysts for the coupling reaction of terminal alkynes and aryl halides. The coupling reactions of aryl iodides with electron‐withdrawing groups showed better results. Copyright © 2014 John Wiley & Sons, Ltd.     

Three‐dimensional frameworks built from piperazine‐2,5‐dione and simple metal salts (M = Co,Ni, Cu and Ag)

Compounds trans‐tetraaquadichloridocobalt(II)–piperazine‐2,5‐dione (1/1), [CoCl₂(H₂O)₄]·C₄H₆N₂O₂, (I), and trans‐tetraaquadichloridonickel(II)–piperazine‐2,5‐dione (1/1), [NiCl₂(H₂O)₄]·C₄H₆N₂O₂, (II), are isomorphous. In each structure, the metal complex and the piperazinedione unit both lie across centres of inversion in the space group P2₁/n. The [MCl₂(H₂O)₄] units (M = Co or Ni) are linked by O—H...Cl hydrogen bonds into sheets of R₂²(8) and R₄²(12) rings, and these sheets are linked by the piperazinedione components via a combination of O—H...O and N—H...Cl hydrogen bonds into a three‐dimensional framework. In catena‐poly[[[trans‐diaquacopper(II)]‐di‐μ‐chlorido] piperazine‐2,5‐dione solvate], {[CuCl₂(H₂O)₂]·C₄H₆N₂O₂}_n, (III), the metal ion and the piperazine unit both lie across centres of inversion in the space group I2/a. The coordination polymer forms chains of centrosymmetric [CuCl₂(H₂O)₂] units running parallel to [010] and these are linked by the piperazinedione units into a three‐dimensional framework structure. In poly[μ₃‐nitrato‐μ₂‐piperazine‐2,5‐dione‐silver(I)], [Ag(NO₃)(C₄H₆N₂O₂)]_n, (IV), the silver and nitrate ions lie on mirror planes in the space group Pnma, while the piperazinedione unit lies across a centre of inversion. The compound is a coordination polymer containing five‐coordinate approximately square‐pyramidal Ag, in which the ligating O atoms are derived from three different nitrate ligands and two different piperazinedione ligands. The ionic components form sheets in which each anion is coordinated to three different cations, and these sheets are linked into a three‐dimensional framework by the organic ligands, each of which coordinates to two different Ag centres. The significance of this study lies in its demonstration of a wide variety of framework types built from a common and very simple organic component with simple metal salts.     

Two isomorphous crotonatolanthanide complexes: tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)Ln]–2,6‐diaminopurine (1/2) (Ln = Dy and Ho)

The title isomorphous compounds, tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)dysprosium(III)]–2,6‐diaminopurine (1/2), [Dy₂(C₄H₅O₂)₆(H₂O)₄]·2C₅H₆N₆, and tetra‐μ‐but‐2‐enoato‐bis[diaqua(but‐2‐enoato)holmium(III)]–2,6‐diaminopurine (1/2), [Ho₂(C₄H₅O₂)₆(H₂O)₄]·2C₅H₆N₆, consist of [Ln(crot)₃(H₂O)₂]₂ dimers (crot is crotonate or but‐2‐enoate; Ln is the lanthanide cation), built up around inversion centres and completed by 2,6‐diaminopurine molecules. The lanthanide cation is coordinated by three chelating crotonate units and two water molecules. One of the chelating carboxylate groups acts also in a bridging mode sharing one O atom with both cations and the final result is a pair of DyO₉ tricapped prismatic polyhedra linked to each other through a central (Dy—O)₂ loop. A feature of the structures is the existence of a complex intermolecular interaction scheme involving two sets of tightly interlinked non‐intersecting one‐dimensional structures, one of them formed by the [Dy(crot)₃(H₂O)₂]₂ dimers (running along [100] and linked by O—H...O hydrogen bonds) and the second formed by 2,6‐diaminopurine molecules (evolving along [010] linked by N—H...N hydrogen bonds).     

N‐Benzyl‐2,5‐bis(2‐thienyl)­pyrrole

The solid‐state structure of the title compound, C₁₉H₁₅NS₂, is unusual among substituted thiophene/pyrrole derivatives in that the molecular packing is dominated by π–π interactions between the benzyl substituents. This may be due to the large torsion angles observed between adjacent heterocycles. Torsion angles between adjacent rings in poly­pyrrole and poly­thio­phene conducting polymers are related to conjugation length and the conductivity properties of the polymer materials. The title compound crystallizes in space group P2₁/c with two mol­ecules in the asymmetric unit, both of which exhibit disorder in one of their thio­phene rings.     

Bis(2,5‐dimethoxy‐4‐methylphenyl)methane and bis(2,5‐dimethoxy‐3,4,6‐trimethylphenyl)methane

Bis(2,5‐di­methoxy‐4‐methyl­phenyl)­methane, C₁₉H₂₄O₄, (IIa), was obtained and characterized as a minor product from the reaction of tolu­hydro­quinone di­methyl ether (1,4‐dimethoxy‐2‐methylbenzene) with N‐(hydroxy­methyl)­tri­fluoro­acet­amide. Similarly, bis(2,5‐di­methoxy‐3,4,6‐tri­methyl­phenyl)­methane, C₂₃H₃₂O₄, (IIb), was prepared from the corresponding reaction of tri­methyl­hydro­quinone di­methyl ether (2,5‐dimethoxy‐1,3,4‐trimethylbenzene). The mol­ecules of (IIa) and (IIb) each lie on a twofold axis passing through the methyl­ene group. The dihedral angle between the planar phenyl rings is 73.4 (1)° in (IIa) and 77.9 (1)° in (IIb). The external bond angles around the bridging methyl­ene group are 116.6 (2) and 117.3 (2)° for (IIa) and (IIb), respectively. In (IIa), the methoxy substituents lie in the plane of the ring and are conjugated with the aromatic system, whereas in (IIb), they are almost perpendicular to the phenyl ring and are positioned on opposite sides.     

Two [Cu2I2]‐based coordination polymers of 1,3‐bis(pyridin‐4‐yl)propane

Solvothermal reactions of Cu₂(OH)₂CO₃ with 1,3‐bis(pyridin‐4‐yl)propane (bpp) in the presence of aqueous ammonia in 4‐iodotoluene/CH₃CN or 1,4‐diiodobenzene/CH₃CN afforded two [Cu₂I₂]‐based coordination polymers, namely catena‐poly[[[di‐μ‐iodido‐dicopper(I)]‐bis[μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′]] p‐toluidine tetrasolvate], {[Cu₂I₂(C₁₃H₁₄N₂)₂]·4C₇H₉N}_n, (I), and the analogous 1,4‐diiodobenzene monosolvate, {[Cu₂I₂(C₁₃H₁₄N₂)₂]·C₆H₄I₂}_n, (II). The [Cu₂I₂] unit of (I) lies on a centre of symmetry at the mid‐point of the two I atoms, while that of (II) has a twofold axis running through the I...I line. In (I) and (II), each Cu centre is tetrahedrally coordinated by two μ‐I and two N atoms from two different bpp ligands. Each rhomboid [Cu₂I₂] unit can be considered as a four‐connecting node linked to the symmetry‐related [Cu₂I₂] units via two pairs of bpp ligands to form a one‐dimensional double chain along the c axis. The dimensions of the [Cu₂I₂(bpp)₂]₂ rings in (I) and (II) are different, which may be due to the presence of different guest solvent molecules in the structures. In (I), one p‐toluidine molecule, derived from an Ullmann coupling reaction of 4‐iodotoluene with ammonia, interacts with the [Cu₂I₂] cluster fragment through N—H...I hydrogen bonds, while the two p‐toluidine molecules interact via N—H...N hydrogen bonds. In (II), two I atoms of each 1,4‐diiodobenzene molecule are linked to the I atoms of the [Cu₂I₂] fragments from a neighbouring chain via I...I secondary interactions.     

1‐(4‐Methyl­amino‐1,2,5‐thia­diazo­le‐3‐carbonyl)­thio­semicarbazide

In the title compound, C₅H₈N₆OS₂, the supramol­ecular architecture is sustained by two N—H...O and three N—H...S hydrogen bonds, and by N...S electrostatic interactions. The hydrogen‐bond network generates a sheet structure, which extends in the a and b directions and is one c‐cell dimension thick. These extended sheets are then linked across inversion centres in the c direction by N...S electrostatic interactions, thus forming a three‐dimensional network. The principal intermolecular dimensions include N(H)...O distances of 2.8393 (17) and 3.0268 (16) Å, N(H)...S distances in the range 3.2896 (14)–3.5924 (16) Å and N...S distances of 3.0822 (16) Å.     

Three‐dimensional hydrogen‐bonding supramolecular architecture of 2‐(3‐pyridinio)‐5‐(3‐pyridyl)‐1,3,4‐oxa­diazole perchlorate

In the crystal structure of the title compound, C₁₂H₉N₄O⁺·ClO₄⁻, the protonated cation adopts a cis‐I conformation and approximately planar geometry. Each perchlorate anion acts as the acceptor of three C—H⋯O weak interactions, which, together with N—H⋯N and C—H⋯N hydrogen bonds between the protonated cations, extend this structure into a three‐dimensional hydrogen‐bonded network.     

Comparison of the hydrogen‐bond patterns in 2‐amino‐1,3,4‐thiadiazolium hydrogen oxalate, 2‐amino‐1,3,4‐thiadiazole–succinic acid (1/2), 2‐amino‐1,3,4‐thiadiazole–glutaric acid (1/1) and 2‐amino‐1,3,4‐thiadiazole–adipic acid (1/1)

The X‐ray single‐crystal structure determinations of the chemically related compounds 2‐amino‐1,3,4‐thiadiazolium hydrogen oxalate, C₂H₄N₃S⁺·C₂HO₄⁻, (I), 2‐amino‐1,3,4‐thiadiazole–succinic acid (1/2), C₂H₃N₃S·2C₄H₆O₄, (II), 2‐amino‐1,3,4‐thiadiazole–glutaric acid (1/1), C₂H₃N₃S·C₅H₈O₄, (III), and 2‐amino‐1,3,4‐thiadiazole–adipic acid (1/1), C₂H₃N₃S·C₆H₁₀O₄, (IV), are reported and their hydrogen‐bonding patterns are compared. The hydrogen bonds are of the types N—H...O or O—H...N and are of moderate strength. In some cases, weak C—H...O interactions are also present. Compound (II) differs from the others not only in the molar ratio of base and acid (1:2), but also in its hydrogen‐bonding pattern, which is based on chain motifs. In (I), (III) and (IV), the most prominent feature is the presence of an R₂²(8) graph‐set motif formed by N—H...O and O—H...N hydrogen bonds, which are present in all structures except for (I), where only a pair of N—H...O hydrogen bonds is present, in agreement with the greater acidity of oxalic acid. There are nonbonding S...O interactions present in all four structures. The difference electron‐density maps show a lack of electron density about the S atom along the S...O vector. In all four structures, the carboxylic acid H atoms are present in a rare configuration with a C—C—O—H torsion angle of ∼0°. In the structures of (II)–(IV), the C—C—O—H torsion angle of the second carboxylic acid group has the more common value of ∼|180|°. The dicarboxylic acid molecules are situated on crystallographic inversion centres in (II). The Raman and IR spectra of the title compounds are presented and analysed.     

Two bicyclic dinuclear complexes generated from 3,3′‐[1,3,4‐thiadiazole‐2,5‐diyldi(thiomethylene)]dibenzoic acid (L) and dimethylformamide (DMF): [Cu(L)(DMF)]2 and [Zn(L)(DMF)]2

A new 1,3,4‐thiadiazole bridging ligand, namely 3,3′‐[1,3,4‐thiadiazole‐2,5‐diyldi(thiomethylene)]dibenzoic acid (L), has been used to create the novel isomorphous complexes bis{μ‐3,3′‐[1,3,4‐thiadiazole‐2,5‐diyldi(thiomethylene)]dibenzoato}bis[(N,N‐dimethylformamide)copper(II)], [Cu₂(C₁₈H₁₂N₂O₄S₃)₂(C₃H₇NO)₂], (I), and bis{μ‐3,3′‐[1,3,4‐thiadiazole‐2,5‐diyldi(thiomethylene)]dibenzoato}bis[(N,N‐dimethylformamide)zinc(II)], [Zn₂(C₁₈H₁₂N₂O₄S₃)₂(C₃H₇NO)₂], (II). Both exist as centrosymmetric bicyclic dimers constructed through the syn–syn bidentate bridging mode of the carboxylate groups. The two rings share a metal–metal bond and each of the metal atoms possesses a square‐pyramidal geometry capped by the dimethylformamide molecule. The 1,3,4‐thiadiazole rings play a critical role in the formation of a π–π stacking system that expands the dimensionality of the structure from zero to one. The thermogravimetric analysis of (I) indicates decomposition of the coordinated ligands on heating. Compared with the fluorescence of L in the solid state, the fluorescence intensity of (II) is relatively enhanced with a slight redshift, while that of (I) is quenched.     

5‐n‐Butylpyridine‐2‐carboxylate–copper(II) and –iron(III) complexes

In trans‐bis(5‐n‐butyl­pyridine‐2‐carboxyl­ato‐κ²N,O)­bis­(methanol‐κO)copper(II), [Cu(C₁₀H₁₂NO₂)₂(CH₄O)₂], the Cu atom lies on a centre of symmetry and has a distorted octahedral coordination. The Cu—O(methanol) bond length in the axial direction is 2.596 (3) Å, which is much longer than the Cu—­O(carboxylate) and Cu—N distances in the equatorial plane [1.952 (2) and 1.977 (2) Å, respectively]. In mer‐tris(5‐n‐bu­tyl­pyridine‐2‐carboxyl­ato‐κ²N,O)­iron(III), [Fe(C₁₀H₁₂NO₂)₃], the Fe atom also has a distorted octahedral geometry, with Fe—O and Fe—N bond‐length ranges of 1.949 (4)–1.970 (4) and 2.116 (5)–2.161 (5) Å, respectively. Both crystals are stabilized by stacking interactions of the 5‐n‐butyl­pyridine‐2‐carboxyl­ate ligand, although hydrogen bonds also contribute to the stabilization of the copper(II) complex.     

Diaquabis(2,5‐dihydroxybenzoato‐κO)bis(1,10‐phenanthroline‐κ2N,N′)strontium(II) bis(1,10‐phenanthroline) tetrahydrate

The title compound, [Sr(C₇H₅O₄)₂(C₁₂H₈N₂)₂(H₂O)₂]·2C₁₂H₈N₂·4H₂O, consists of an Sr^II complex, uncoordinated phenanthroline (phen) molecules and solvent water molecules. The Sr^II ion is located on a twofold axis and is coordinated by two phen ligands, two dihydroxybenzoate anions and two water molecules in a distorted tetragonal antiprismatic geometry. Partially overlapped arrangements exist between parallel coordinated and parallel uncoordinated phen rings; the face‐to‐face separations between the former (coordinated) and the latter (uncoordinated) rings are 3.436 (13) and 3.550 (14) Å, respectively. This difference suggests the effect of metal coordination on π–π stacking between phen rings.     

Two polymorphs of bis(2‐carbamoylguanidinium) fluorophosphonate dihydrate

Two polymorphs of bis(2‐carbamoylguanidinium) fluorophosphonate dihydrate, 2C₂H₇N₄O⁺·FO₃P²⁻·2H₂O, are presented. Polymorph (I), crystallizing in the space group Pnma, is slightly less densely packed than polymorph (II), which crystallizes in Pbca. In (I), the fluorophosphonate anion is situated on a crystallographic mirror plane and the O atom of the water molecule is disordered over two positions, in contrast with its H atoms. The hydrogen‐bond patterns in both polymorphs share similar features. There are O—H...O and N—H...O hydrogen bonds in both structures. The water molecules donate their H atoms to the O atoms of the fluorophosphonates exclusively. The water molecules and the fluorophosphonates participate in the formation of R⁴₄(10) graph‐set motifs. These motifs extend along the a axis in each structure. The water molecules are also acceptors of either one [in (I) and (II)] or two [in (II)] N—H...O hydrogen bonds. The water molecules are significant building elements in the formation of a three‐dimensional hydrogen‐bond network in both structures. Despite these similarities, there are substantial differences between the hydrogen‐bond networks of (I) and (II). The N—H...O and O—H...O hydrogen bonds in (I) are stronger and weaker, respectively, than those in (II). Moreover, in (I), the shortest N—H...O hydrogen bonds are shorter than the shortest O—H...O hydrogen bonds, which is an unusual feature. The properties of the hydrogen‐bond network in (II) can be related to an unusually long P—O bond length for an unhydrogenated fluorophosphonate anion that is present in this structure. In both structures, the N—H...F interactions are far weaker than the N—H...O hydrogen bonds. It follows from the structure analysis that (II) seems to be thermodynamically more stable than (I).     

Two polymorphs of bis(2‐bromophenyl) di­sulfide

Colourless crystals of the title compound, bis(2‐bromo­phenyl) di­sulfide, C₁₂H₈Br₂S₂, are obtained from the reaction of 2‐bromo­phenyl­mercaptan with metallic sodium and either zinc chloride or cadmium chloride in methanol. In the presence of Zn^II ions, the crystals are orthorhombic (space group Pbca, with Z′ = 1); with Cd^II ions present, the product is triclinic (space group , with Z′ = 4). Both polymorphs exhibit significant intramolecular C—H⋯S hydrogen bonds. In the ortho­rhombic form, mol­ecules are linked by intermolecular C—H⋯Br hydrogen bonds, while in the triclinic form, mol­ecules exhibit Br⋯Br contacts.     

Hydrogen‐bonded molecular ladders in 1,4‐bis(4‐chlorophenylsulfonyl)‐2,5‐dimethylbenzene

In the title compound, C₂₀H₁₆Cl₂O₄S₂, the mol­ecules lie across centres of inversion. A single type of intermolecular C—H?O hydrogen bond, with a C?O distance of 3.254 (3) Å and a C—H?O angle of 132°, links the mol­ecules into ladders whose uprights form C(6) chains and whose rungs enclose centrosymmetric R(22) rings.     

Diastereoisomeric β‐ethyl aspartate–cobalt(III) complexes: Λ(+)578‐ and Δ(−)578‐bis(ethane‐1,2‐diamine)[β‐ethyl (S)‐aspartato]cobalt(III) bis(perchlorate) monohydrate

The structures of the diastereoisomers Λ(+)₅₇₈‐, (I), and Δ(−)₅₇₈‐bis(ethane‐1,2‐diamine)[β‐ethyl (S)‐aspartato‐κ²N,O¹]cobalt(III) bis(perchlorate) monohydrate, (II), both [Co(C₆H₁₀N₂O₄)(C₂H₈N₂)₂](ClO₄)₂·H₂O, are compared. In both structures, the ester group of the amino acid side chain is engaged only in intramolecular hydrogen bonding to coordinated amine groups. This interaction is stronger in (I) and correlates with previously observed diastereoisomeric equilibrium ratios for related metal complex systems in aqueous media. The two perchlorate anions of (II) are located on twofold axes. Both perchlorates in (I) and one of the perchlorates in (II) are affected by disorder. Both structures exhibit extensive three‐dimensional hydrogen‐bonding networks.