Three isotypic polymeric complexes with rare earth cations,but‐2‐enoate anions and 4,4′‐(ethane‐1,2‐diyl)dipyridine and 4,4′‐(ethene‐1,2‐diyl)dipyridine bridging ligands

Three isotypic rare earth complexes, catena‐poly[[aquabis(but‐2‐enoato‐κ²O,O′)yttrium(III)]‐bis(μ‐but‐2‐enoato)‐κ³O,O′:O;κ³O:O,O′‐[aquabis(but‐2‐enoato‐κ²O,O′)yttrium(III)]‐μ‐4,4′‐(ethane‐1,2‐diyl)dipyridine‐κ²N:N′], [Y₂(C₄H₅O₂)₆(C₁₂H₁₂N₂)(H₂O)₂], the gadolinium(III) analogue, [Gd₂(C₄H₅O₂)₆(C₁₂H₁₂N₂)(H₂O)₂], and the gadolinium(III) analogue with a 4,4′‐(ethene‐1,2‐diyl)dipyridine bridging ligand, [Gd₂(C₄H₅O₂)₆(C₁₂H₁₀N₂)(H₂O)₂], are one‐dimensional coordination polymers made up of centrosymmetric dinuclear [M(but‐2‐enoato)₃(H₂O)]₂ units (M = rare earth), further bridged by centrosymmetric 4,4′‐(ethane‐1,2‐diyl)dipyridine or 4,4′‐(ethene‐1,2‐diyl)dipyridine spacers into sets of chains parallel to the [20] direction. There are intra‐chain and inter‐chain hydrogen bonds in the structures, the former providing cohesion of the linear arrays and the latter promoting the formation of broad planes parallel to (010).     

Bis{2‐[(phenylimino)ethyl]‐1H‐pyrrol‐1‐ido‐κ2N,N′}nickel(II): a supramolecular structure formed by C—H...π hydrogen bonds

In the title compound, [Ni(C₁₂H₁₁N₂)₂], the Ni^II cation lies on an inversion centre and has a square‐planar coordination geometry. This transition metal complex is composed of two deprotonated N,N′‐bidentate 2‐[(phenylimino)ethyl]‐1H‐pyrrol‐1‐ide ligands around a central Ni^II cation, with the pyrrolide rings and imine groups lying trans to each other. The Ni—N bond lengths range from 1.894 (3) to 1.939 (2) Å and the bite angle is 83.13 (11)°. The Ni—N(pyrrolide) bond is substantially shorter than the Ni—N(imino) bond. The planes of the phenyl rings make a dihedral angle of 78.79 (9)° with respect to the central NiN₄ plane. The molecules are linked into simple chains by an intermolecular C—H...π interaction involving a phenyl β‐C atom as donor. Intramolecular C—H...π interactions are also present.     

A comparative study of the packing of two polymorphs of the nickel(II) pincer complex [2,6‐bis(di‐tert‐butylphosphinoyl)‐4‐(3,5‐dinitrobenzoyloxy)phenyl‐κ3P,C1,P′]chloridonickel(II)

Pincer complexes can act as catalysts in organic transformations and have potential applications in materials, medicine and biology. They exhibit robust structures and high thermal stability attributed to the tridentate coordination of the pincer ligands and the strong σ metal–carbon bond. Nickel derivatives of these ligands have shown high catalytic activities in cross‐coupling reactions and other industrially relevant transformations. This work reports the crystal structures of two polymorphs of the title Ni^II POCOP pincer complex, [Ni(C₂₉H₄₁N₂O₈P₂)Cl] or [NiCl{C₆H₂‐4‐[OCOC₆H₄‐3,5‐(NO₂)₂]‐2,6‐(OP^tBu₂)₂}]. Both pincer structures exhibit the Ni^II atom in a distorted square‐planar coordination geometry with the POCOP pincer ligand coordinated in a typical tridentate manner via the two P atoms and one arene C atom via a C—Ni σ bond, giving rise to two five‐membered chelate rings. The coordination sphere of the Ni^II centre is completed by a chloride ligand. The asymmetric units of both polymorphs consist of one molecule of the pincer complex. In the first polymorph, the arene rings are nearly coplanar, with a dihedral angle between the mean planes of 27.9 (1)°, while in the second polymorph, this angle is 82.64 (1)°, which shows that the arene rings are almost perpendicular to one another. The supramolecular structure is directed by the presence of weak C—H…O=X (X = C or N) interactions, forming two‐ and three‐dimensional chain arrangements.     

[(8a,9,9a‐η)‐9‐(η5‐Cyclopentadienyl)‐9‐nickelafluorenyl](η5‐pentamethylcyclopentadienyl)nickel(II)

The title compound, [Ni₂(C₅H₅)(C₁₀H₁₅)(C₁₂H₈)] or [Ni(C₁₀H₁₅){Ni(C₅H₅)(C₁₂H₈)}], is a rare example (and the first obtained from nickelafluorenyllithium) of an analogue of nickelocene in which the central Ni atom is coordinated to one pentamethylcyclopentadienyl ring and one nickelafluorenyl ring. Both rings lie almost parallel to one another: the dihedral angle between the planes which include these rings is 4.4 (1)°. Slip parameter analysis indicates that the bonding mode of the central Ni atom to the nickelacyclic ring is between η³ and η⁵. Two‐dimensional layers of molecules are formed by C—H...π interactions.     

1,1′‐Di(hydrazinocarbonylmethyl)‐2,2′‐biimidazole monohydrate and 1,1′‐di[2‐(hydrazinocarbonyl)ethyl]‐2,2′‐bi­imidazole

The crystal structures of the title compounds, alternatively called 2,2′‐(2,2′‐bi­imid­azole‐1,1′‐diyl)­diaceto­hydra­zide monohydrate, C₁₀H₁₄N₈O₂·H₂O, (I), and 3,3′‐(2,2′‐bi­imid­azole‐1,1′‐diyl)­dipropion­o­hydra­zide, C₁₂H₁₈N₈O₂, (II), respectively, have been determined. The mol­ecules consist of half‐mol­ecule asymmetric units related by a twofold rotation in (I) and by a center of inversion in (II). The imidazole rings of both mol­ecules crystallize in a nearly coplanar fashion [dihedral angles of 5.91 (3) and 0.0 (1)° for (I) and (II), respectively]. Both planar hy­dra­zinocarbonylalkyl substituents are essentially planar and assume the E orientation.     

rac‐ and meso‐3,3′‐Bis(3,5‐di­methyl­phenyl)‐3H,3′H‐2,2′‐biindenyl­idene‐1,1′(2H,2′H)‐dione

In the rac isomer of the title compound, C₃₄H₂₈O₂, the two C—Ph_{di­methyl­phenyl} bond axes make an angle of 58.7 (1)°. There is no short contact between the two 3,5‐di­methyl­phenyl rings, although the dihedral angle between them is 4.93 (7)°. The meso isomer has a center of symmetry at the middle of the C=C bond, and the two C—Ph_{di­methyl­phenyl} bond axes are antiparallel to one another.     

1‐(2‐Methyl‐5‐phenyl‐3‐thien­yl)‐2‐(3‐methyl‐5‐phenyl‐2‐thien­yl)‐3,3,4,4,5,5‐hexa­fluoro­cyclo­pent‐1‐ene: a novel photochromic hybrid diaryl­ethene

The title compound, C₂₇H₁₈F₆S₂, a novel photochromic hybrid diaryl­ethene derivative containing 2‐ and 3‐thienyl substituents, is one of the most promising photochromic candidates with shorter wavelength for optical storage and other optoelectronic devices. In the crystal structure, the mol­ecule adopts a photoactive antiparallel conformation. The distance between the two reactive C atoms, i.e. the ring C atoms to which the methyl groups are attached, is 3.430 (4) Å. The dihedral angles between the thienyl and adjacent phenyl rings are 26.8 (2) and 33.98 (9)°.     

Linear hydrogen‐bonded molecular tapes in the cocrystals of squaric acid with 4,4′‐dipyridylacetylene and 1,2‐bis(4‐pyridyl)ethylene

The title compounds, 4,4′‐(ethyne‐1,2‐diyl)­dipyridinium bis(squarate), C₁₂H₁₀N₂²⁺·2C₄HO₄^?, and 4,4′‐(ethene‐1,2‐diyl)­dipyridinium bis­(squarate), C₁₂H₁₂N₂²⁺·2C₄HO₄^?, are isomorphous and crystallize in space group P. The cocrystals contain linear hydrogen‐bonded molecular tape structures along the [120] direction. The squarate monoanions form a ten‐membered dimer linked by two intermolecular O—H?O hydrogen bonds. Each component mol­ecule forms a segregated stack along the c axis. The bond lengths of the squarate monoanion indicate delocalization of the enolate anion.     

The inner‐salt zwitterion,the dihydrochloride dihydrate and the dimethyl sulfoxide disolvate of 3,6‐bis(pyridin‐2‐yl)pyrazine‐2,5‐dicarboxylic acid

In the inner‐salt zwitterion of 3,6‐bis(pyridin‐2‐yl)pyrazine‐2,5‐dicarboxylic acid, (I), namely 5‐carboxy‐3‐(pyridin‐1‐ium‐2‐yl)‐6‐(pyridin‐2‐yl)pyrazine‐2‐carboxylate, [C₁₆H₁₀N₄O₄, (Ia)], the pyrazine ring has a twist–boat conformation. The opposing pyridine and pyridinium rings are almost perpendicular to one another, with a dihedral angle of 80.24 (18)°, and are inclined to the pyrazine mean plane by 36.83 (17) and 43.74 (17)°, respectively. The carboxy and carboxylate groups are inclined to the mean plane of the pyrazine ring by 43.60 (17) and 45.46 (17)°, respectively. In the crystal structure, the molecules are linked via N—H...O and O—H...O hydrogen bonds, leading to the formation of double‐stranded chains propagating in the [010] direction. On treating (Ia) with aqueous 1 M HCl, the diprotonated dihydrate form 2,2′‐(3,6‐dicarboxypyrazine‐2,5‐diyl)bis(pyridin‐1‐ium) dichloride dihydrate [C₁₆H₁₂N₄O₄²⁺·2Cl⁻·2H₂O, (Ib)] was obtained. The cation lies about an inversion centre. The pyridinium rings and carboxy groups are inclined to the planar pyrazine ring by 55.53 (9) and 19.8 (2)°, respectively. In the crystal structure, the molecules are involved in N—H...Cl, O—H...O_water and O_water—H...Cl hydrogen bonds, leading to the formation of chains propagating in the [010] direction. When (Ia) was recrystallized from dimethyl sulfoxide (DMSO), the DMSO disolvate 3,6‐bis(pyridin‐2‐yl)pyrazine‐2,5‐dicarboxylic acid dimethyl sulfoxide disolvate [C₁₆H₁₀N₄O₄·2C₂H₆OS, (Ic)] of (I) was obtained. Here, the molecule of (I) lies about an inversion centre and the pyridine rings are inclined to the planar pyrazine ring by only 23.59 (12)°. However, the carboxy groups are inclined to the pyrazine ring by 69.0 (3)°. In the crystal structure, the carboxy groups are linked to the DMSO molecules by O—H...O hydrogen bonds. In all three crystal structures, the presence of nonclassical hydrogen bonds gives rise to the formation of three‐dimensional supramolecular architectures.     

(η5‐Cyclopentadienyl)[(1,2,3,4,4a,10a‐η)‐1‐methylthianthrene]iron(II) hexafluoridophosphate acetone 0.33‐solvate

The title complex salt, [Fe(C₅H₅)(C₁₃H₁₀S₂)]PF₆·0.33C₃H₆O, obtained from an acetone–diethyl ether–dichloromethane mixture at 280 (2) K, has three cationic molecules (A–C), three hexafluoridophosphate counter‐anions and one acetone solvent molecule in the asymmetric unit. Two of the three cations contain FeCp (Cp is cyclopentadienyl) inside the fold of the heterocycle. The dihedral angles between the planes of the external (complexed and uncomplexed) benzene rings in the thianthrene molecule are 146.5 (2)° for FeCp‐out‐of‐fold molecule A, and 139.0 (3) and 142.5 (2)° for the two FeCp‐in‐fold molecules B and C, respectively. The complexed Cp and benzene rings in each molecule are almost parallel, with a dihedral angle between the planes of 0.2 (5)° for molecule A, 2.8 (5)° for B, and 2.19 (4) and 6.86 (6)° for the disordered Cp ring in C.     

Five N′‐benzylidene‐N‐methylpyrazine‐2‐carbohydrazides

The compounds N′‐benzylidene‐N‐methylpyrazine‐2‐carbohydrazide, C₁₃H₁₂N₄O, (IIa), N′‐(2‐methoxybenzylidene)‐N‐methylpyrazine‐2‐carbohydrazide, C₁₄H₁₄N₄O₂, (IIb), N′‐(4‐cyanobenzylidene)‐N‐methylpyrazine‐2‐carbohydrazide dihydrate, C₁₄H₁₁N₅O·2H₂O, (IIc), N‐methyl‐N′‐(2‐nitrobenzylidene)pyrazine‐2‐carbohydrazide, C₁₃H₁₁N₅O₃, (IId), and N‐methyl‐N′‐(4‐nitrobenzylidene)pyrazine‐2‐carbohydrazide, C₁₃H₁₁N₅O₃, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55–78°. These methylated pyrazine‐2‐carbohydrazides have supramolecular structures which are formed by weak C—H...O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π–π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0–6°.     

3,3,4,4,5,5‐Hexa­fluoro‐1,2‐bis(5‐hydroxy­methyl‐2‐methyl‐3‐thienyl)­cyclo­pent‐1‐ene

The title compound, C₁₇H₁₄F₆O₂S₂, a photochromic di­aryl­ethene, is one of the most promising materials for optical memories and other optoelectronic devices. The hexafluoro­cyclopentene group and the two thio­phene rings are all planar, and the dihedral angles between the cyclo­pentene ring and the adjacent thio­phene rings are 46.4 (1) and 49.5 (1)°.     

[N,N′‐Bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminato]­nickel(II) and [N,N′‐bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminato]copper(II)

In the title compounds, {2,2′‐[2,2‐di­methyl‐1,3‐propane­diyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴N,N′,O,O′}nickel(II), [Ni(C₁₉H₂₀N₂O₂)], and {2,2′‐[2,2‐di­methyl‐1,3‐propane­diyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴N,N′,O,O′}copper(II), [Cu(C₁₉H₂₀N₂O₂)], the Ni^II and Cu^II atoms are coordinated by two iminic N and two phenolic O atoms of the N,N′‐bis­(salicyl­idene)‐2,2‐di­methyl‐1,3‐propane­diaminate (SALPD^2?, C₁₇H₁₆N₂O₂^2?) ligand. The geometry of the coordination sphere is planar in the case of the Ni^II complex and distorted towards tetrahedral for the Cu^II complex. Both complexes have a cis configuration imposed by the chelate ligand. The dihedral angles between the N/Ni/O and N/Cu/O coordination planes are 17.20 (6) and 35.13 (7)°, respectively.     

4,5,9,10‐Tetrahydro‐4‐methyl‐2‐phenyl‐9,10‐epoxy‐3H,10aH‐cyclobuta[a]benzo[2,3,4‐de]isoquinoline‐3,5‐dione

In the title compound, C₂₁H₁₅NO₃, which is one of the photoreaction products of N‐methyl‐1,8‐naphthalene­dicar­box­imide with phenyl­acetyl­ene, the cyclo­butene and epoxy rings are trans to each other across the cyclo­hexene ring of the tetralin moiety. The dihedral angle between the mean planes of the cyclo­butene and cyclo­hexene rings is 112.80 (2)°, while the latter makes a dihedral angle of 103.70 (9)° with the epoxy ring. The crystal structure is stabilized by C—H⋯O intermolecular interactions.     

{4‐Bromo‐2‐[2‐(5‐bromo‐2‐oxido­benzyl­idene­amino­methyl)­phenyl­imino­methyl]­phenolato‐κ4O,N,N′,O′}nickel(II)

In the title complex, [Ni(C₂₁H₁₄Br₂N₂O₂)], the Ni^II atom is coordinated by the two imine N and two phenolate O atoms of the Schiff base ligand in a tetrahedrally distorted square‐planar geometry. The Ni—N and Ni—O distances are within the ranges expected for Ni–Schiff base derivatives. Intermolecular C—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers, forming (12) (A) and (10) (B) rings. These dimers combine to form a supramolecular ABAB… aggregate which propagates along the [100] direction.     

μ‐{N,N′‐Bis[2‐(dimethyl­amino)ethyl]oxamidato(2–)}‐1κ2O,O′:2κ4N,N′,N′′,N′′′‐bis­(4,4′‐dimethyl‐2,2′‐bipyridine‐1κ2N,N′)dinickel(II) bis­(perchlorate)

In the crystal structure of the title complex, [Ni₂(C₁₀H₂₀N₄O₂)(C₁₂H₁₂N₂)₂](ClO₄)₂ or [Ni(dmaeoxd)Ni(dmbp)₂](ClO₄)₂ {H₂dmaeoxd is N,N′‐bis­[2‐(dimethyl­amino)ethyl]oxamide and dmbp is 4,4′‐dimethyl‐2,2′‐bipyridine}, the deprotonated dmaeoxd²⁻ ligand is in a cis conformation and bridges two Ni^II atoms, one of which is located in a slightly distorted square‐planar environment, while the other is in an irregular octa­hedral environment. The cation is located on a twofold symmetry axis running through both Ni atoms. The dmaeoxd²⁻ ligands inter­act with each other via C—H⋯O hydrogen bonds and π–π inter­actions, which results in an extended chain along the c axis.     

A new one‐dimensional nickel metal–organic framework: catena‐poly[[[diaquabis(4‐{[(1‐phenyl‐1H‐tetrazol‐5‐yl)sulfanyl]methyl}benzoato‐κO)nickel(II)]‐μ‐4,4′‐bipyridine‐κ2N:N′] monohydrate]

The title complex, {[Ni(C₁₅H₁₁N₄O₂S)₂(C₁₀H₈N₂)(H₂O)₂]·H₂O}_n, was synthesized by the reaction of nickel chloride, 4‐{[(1‐phenyl‐1H‐tetrazol‐5‐yl)sulfanyl]methyl}benzoic acid (HL) and 4,4′‐bipyridine (bpy) under hydrothermal conditions. The asymmetric unit contains two half Ni^II ions, each located on an inversion centre, two L⁻ ligands, one bpy ligand, two coordinated water molecules and one unligated water molecule. Each Ni^II centre is six‐coordinated by two monodentate carboxylate O atoms from two different L⁻ ligands, two pyridine N atoms from two different bpy ligands and two terminal water molecules, displaying a nearly ideal octahedral geometry. The Ni^II ions are bridged by 4,4′‐bipyridine ligands to afford a linear array, with an Ni...Ni separation of 11.361 (1) Å, which is further decorated by two monodentate L⁻ ligands trans to each other, resulting in a one‐dimensional fishbone‐like chain structure. These one‐dimensional fishbone‐like chains are further linked by O—H...O, O—H...N and C—H...O hydrogen bonds and π–π stacking interactions to form a three‐dimensional supramolecular architecture. The thermal stability of the title complex was investigated via thermogravimetric analysis.     

μ‐Aqua‐penta­aqua­[μ‐3,6‐bis(6‐methyl‐2‐pyridyl)­pyridazine]­chloro­dinickel(II) trichloride trihydrate

The title compound, μ‐aqua‐1:2κ²O‐penta­aqua‐1κ²O,2κ³O‐μ‐3,6‐bis(6‐methyl‐2‐pyridyl)­pyridazine‐1κ²N¹,N⁶:2κ²N²,N³‐chloro‐1κCl‐dinickel(II) trichloride trihydrate, [Ni₂Cl(C₁₆H₁₄­N₄)(H₂O)₆]Cl₃·3H₂O, consists of two Ni^II atoms, a 3,6‐bis(6‐methyl‐2‐pyridyl)­pyridazine mol­ecule, four Cl atoms and nine water mol­ecules. The two Ni atoms are octahedrally coordinated by N and Cl atoms, and by water mol­ecules, and the three six‐membered rings, a pyridazine and two picolines, are planar to within 0.181 (3) Å. The crystal structure is stabilized by an intra‐ and intermolecular hydrogen‐bonding scheme involving water–water and water–chlorine interactions.     

1‐(2,4,6‐Tri­methyl­phenyl)‐1H‐1,2,3,4‐tetrazole

In the title compound, C₁₀H₁₂N₄, the tetrazole and phenyl rings are planar to within 0.001 (2) and 0.006 (2) Å, respectively. The two rings are not coplanar and have a dihedral angle of 69.07 (9)° between them. Each mol­ecule is connected with two adjacent ones by C—H?N bridges between atoms of tetrazole rings forming chains parallel with the y axis of the unit cell.     

Interactions between dimers of {1,1′‐[o‐phenylenebis(nitrilomethylidyne)]di‐2‐naphtholato‐κ4O,N,N′,O′}nickel(II)

In the title compound, [Ni(C₂₈H₁₈N₂O₂)], the Ni^II centre has a square‐planar coordination geometry in which the Schiff base ligand acts as a cis‐O,N,N′,O′‐tetradentate ligand. The crystal structure is built up of centrosymmetric dimer units stacked into chains along the [010] direction. Adjacent chains associate via C—H...O hydrogen bonding only, leading to a two‐dimensional sheet‐like structure consisting of layers parallel to (10). The cofacial dimeric complex contains an Ni...Ni contact of 3.291 (4) Å.