2,2′‐Methyl­enebis(3‐hydroxy‐5,5‐di­methyl­cyclo­hex‐2‐en‐1‐one)

The title compound, C₁₇H₂₄O₄, crystallizes with two independent mol­ecules, both lying across twofold rotation axes in space group Pccn, in a unit cell whose dimensions closely mimic those of a tetragonal cell. Each mol­ecule contains paired O—H⋯O hydrogen bonds [H⋯O = 1.81 and 1.83 Å, O⋯O = 2.640 (2) and 2.642 (2) Å, and O—H⋯O = 168 and 162°].     

6‐(1‐Hydro­xy‐2,2‐di­phenyl­ethyl)‐4,4‐di­phenyl‐2‐cyclo­hexen‐1‐one

The crystal structure of the title compound, C₃₂H₂₈O₂, (I), confirms the erythro stereochemistry of the aldol adduct. In the crystal, (I) forms centrosymmetric O—H?O=C hydrogen‐bonded dimers which in turn are connected by C—H?O and C—H?π interactions.     

1,1′‐Di­acetyl‐3‐hydroxy‐2,2′,3,3′‐tetra­hydro‐3,3′‐bi(1H‐indole)‐2,2′‐dione

In the title compound, C₂₀H₁₆N₂O₅, both of the 1‐acetyl­isatin (1‐acetyl‐1H‐indole‐2,3‐dione) moieties are planar and form a dihedral angle of 74.1 (1)°. Weak intermolecular hydrogen bonds and C—H?π interactions stabilize the packing in the crystal.     

4,4′‐Bipyridyl N,N′‐dioxide–3‐hydroxy‐2‐naphthoic acid (1/2)

4,4′‐Bipyridyl N,N′‐dioxide crystallizes with 3‐hydr­oxy‐2‐naphthoic acid to give a centrosymmetric three‐component adduct, C₁₀H₈N₂O₂·2C₁₁H₈O₃, which is engineered into a two‐dimensional layer structure by two kinds of π–π inter­actions. Weak C—H⋯O inter­actions further link the two‐dimensional structure into a three‐dimensional structure.     

Methyl 2‐hydroxy‐2‐[5′‐hydroxy‐5′‐(1‐hydroxy‐1‐methyl­ethyl)‐5,2′‐di­methyl­per­hydro‐2,2′‐bi­furan­yl‐5‐yl]­acetate

The relative configuration was determined for the title compound, C₁₆H₂₈O₇, which was obtained as a mixture of epimers. There are both intra‐ and intermolecular hydrogen bonds, the latter forming dimers around the crystallographic centres of inversion.     

(1H‐Pyrazole‐κN2)(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)platinum(II) bis(perchlorate) nitromethane monosolvate

The reaction between [PtCl(terpy)]·2H₂O (terpy is 2,2′:6′,2′′‐terpyridine) and pyrazole in the presence of two equivalents of AgClO₄ in nitromethane yields the title compound, [Pt(C₃H₄N₂)(C₁₅H₁₁N₃)](ClO₄)₂·CH₃NO₂, as a yellow crystalline solid. Single‐crystal X‐ray diffraction shows that the dicationic platinum(II) chelate is square planar with the terpyridine ligand occupying three sites and the pyrazole ligand occupying the fourth. The torsion angle subtended by the pyrazole ring relative to the terpyridine chelate is 62.4 (6)°. Density functional theory calculations at the LANL2DZ/PBE1PBE level of theory show that in vacuo the lowest‐energy conformation has the pyrazole ligand in an orientation perpendicular to the terpyridine ligand (i.e. 90°). Seemingly, the stability gained by the formation of hydrogen bonds between the pyrazole NH group and the perchlorate anion in the solid‐state structure is sufficient for the chelate to adopt a higher‐energy conformation.     

Dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylate and bis(dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylato‐κ2N,N′)copper(I) tetrafluoroborate

The single‐crystal X‐ray structures of dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylate, C₁₄H₁₂N₂O₄, and the copper(I) coordination complex bis(dimethyl 2,2′‐bipyridine‐6,6′‐dicarboxylato‐κ²N,N′)copper(I) tetrafluoroborate, [Cu(C₁₄H₁₂N₂O₄)₂]BF₄, are reported. The uncoordinated ligand crystallizes across an inversion centre and adopts the anticipated anti pyridyl arrangement with coplanar pyridyl rings. In contrast, upon coordination of copper(I), the ligand adopts an arrangement of pyridyl donors facilitating chelating metal coordination and an increased inter‐pyridyl twisting within each ligand. The distortion of each ligand contrasts with comparable copper(I) complexes of unfunctionalized 2,2′‐bipyridine.     

Aqua­bis(3‐meth­oxy‐2‐pyridonato)­(2,2′:6′,2′′‐terpyridine)ruthenium(II)–acetonitrile–water (1/1/1)

The title compound, [Ru(C₆H₆NO₂)₂(C₁₅H₁₁N₃)(H₂O)]·CH₃CN·H₂O, is a transfer hydrogenation catalyst supported by nitro­gen‐donor ligands. This octa­hedral Ru^II complex features rare monodentate coordination of 3‐meth­oxy‐2‐pyridonate ligands and inter­ligand S(6)S(6) hydrogen bonding. Comparison of the title complex with a structural analog with unsubstituted 2‐pyridonate ligands reveals subtle differences in the orientation of the ligand planes.     

(2,2′‐Biquinoline‐κ2N,N′)bis(nitrato‐κ2O,O′)copper(II)

In the title monomer, [Cu(NO₃)₂(C₁₈H₁₂N₂)], the six‐coordinated Cu^II atom lies on a twofold axis which bisects one of the ligands (a chelating biquinoline) and duplicates the remaining ligand, a chelating nitrate. The latter binds in a very asymmetric way, consistent with a Jahn–Teller distortion in the coordination polyhedron which, due to the triple chelation, is extremely distorted and difficult to describe in terms of any regular model.     

Synthesis of 3‐Acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐one Derivatives

The cyclization of aryl ketone anilides 3 with diethyl malonate to affords 4‐hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c]‐pyridin‐2,5‐diones 4 in good yields. 3‐Acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 5 are obtained by ring‐opening reaction of 4‐hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c]‐pyridin‐2,5‐diones 4 in the presence of 1,2‐diethylene glycol. The reaction of 3‐acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 5 with hydroxylamine hydrochloride produces 4‐hydroxy‐3‐[N‐hydroxyethanimidoyl]‐1‐phenylpyridin‐2(1H)‐ones 6 from which 3‐alkyloxyiminoacetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 7 are obtained by reacting with alkyl bromides or iodides in the presence of anhydrous potassium carbonate with moderate yields. The similar compounds can be synthesized on refluxing 3‐acetyl‐4‐hydroxy‐1‐phenylpyridin‐2(1H)‐ones 5 with substituted hydroxylamine hydrochloride in the presence of sodium bicarbonate with good yields. Most of the synthesized compounds are characterized by IR and NMR spectroscopic methods.     

Dichloro(4,4′‐dinonyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II)

The title compound, [PtCl₂(C₂₈H₄₄N₂)], is a new square‐planar Pt^II complex con­taining a bi­pyridine moiety with two long alkyl‐chain substituents. The complex forms a segregated packing structure made up of the alkyl‐chain layers and paired coordination sites.     

Tris(2,2′‐bioxazoline‐κ2N,N′)copper(II) diperchlorate and tris(2,2′‐bioxazoline‐κ2N,N′)­nickel(II) diperchlorate

In the two isomorphous title compounds, viz. tris­[2,2′‐bi(4,5‐di­hydro‐1,3‐oxazole)‐κ²N,N′]copper(II) diperchlorate, [Cu(C₆H₈N₂O₂)₃](ClO₄)₂, (I), and tris­[2,2′‐bi(4,5‐di­hydro‐1,3‐oxazole)‐κ²N,N′]­nickel(II) diperchlorate, [Ni(C₆H₈N₂O₂)₃](ClO₄)₂, (II), the M^II ions each have a distorted octahedral coordination geometry formed via six N atoms from three 2,2′‐bioxazoline ligands. For each ligand, the two five‐membered rings are nearly coplanar. It is noteworthy that the Jahn–Teller effect is stronger in (I) than in (II). The three‐dimensional supramolecular structures of (I) and (II) are formed via weak hydrogen‐bonding interactions between O atoms from per­chlorate anions and H atoms from 2,2′‐bioxazoline ligands.     

(Nitro‐κN)[2‐(phenyldiazenyl‐κN2)pyridine‐κN](2,2′:6′,2′′‐terpyridine‐κ3N)ruthenium(II) tetrafluoroborate

The Ru—N bond distances in the title complex, [Ru(NO₂)(C₁₁H₉N₃)(C₁₅H₁₁N₃)]BF₄ or [Ru(NO₂)(tpy)(azpy)]BF₄, [tpy is 2,2′:6′,2′′‐ter­pyridine and azpy is 2‐(phenyl­azo)­pyridine], are Ru—N_py 2.063 (4), Ru—N_azo 2.036 (4), Ru—N_nitro 2.066 (3) Å, and Ru—N_tpy 2.082 (4), 1.982 (3) and 2.074 (4) Å. The azo N atom is trans to the nitro group. The azo N=N bond length is 1.265 (5) Å, which is the shortest found in such complexes to date. This indicates a multiple bond between Ru and the N atom of the nitro group, and π‐­backbonding [dπ(Ru) π*(azo)] is decreased.     

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.     

(1S)‐1‐Phenylethanaminium 4‐{[(1S,2S)‐1‐hydroxy‐2,3‐dihydro‐1H,1′H‐[2,2′‐biinden]‐2‐yl]methyl}benzoate

The title molecular salt, C₈H₁₂N⁺·C₂₆H₂₁O₃⁻, contains a dimeric indane pharmacophore that demonstrates potent anti‐inflammatory activity. The indane group of the anion exhibits some disorder about the α‐C atom, which appears common to many structures containing this group. A model to account for the slight disorder was attempted, but this was deemed unsuccessful because applying bond‐length constraints to all the bonds about the α‐C atom led to instability in the refinement. The absolute configuration was determined crystallographically as S,S,S by anomalous dispersion methods with reference to both the Flack parameter and Bayesian statistics on Bijvoet differences. The configuration was also determined by an a priori knowledge of the absolute configuration of the (1S)‐1‐phenylethanaminium counter‐ion. The molecules pack in the crystal structure to form an infinite two‐dimensional hydrogen‐bond network in the (100) plane of the unit cell.     

Conformational dimorphism of the spiropyran 1′,3′,3′‐trimethylspiro[2H‐1‐benzopyran‐2,2′‐indoline]‐6‐carbaldehyde)

The title compound, C₂₀H₁₉NO₂, crystallizes from an acetone–heptane solution as two dimorphs in the space groups C2/c and Cc. Each dimorph has two molecules in the asymmetric unit. The four molecules adopt slightly different conformations expressed by the degree of bending around a vector connecting the O and C atoms attached to the bridgehead C atom of the pyran ring. Due to the fact that all four molecules are chemically identical, the difference in bending is attributed to packing forces. This is evident from the close contacts of neighbouring molecules perpendicular to the plane of the benzopyran moiety observed in the Cc structure and not in the C2/c structure. These observations provide a unique example that shows how packing forces can affect the conformation of a specific molecule.     

(Aqua‐2κO)bis(2,2′‐bipyridine‐1κ2N,N′){μ‐N‐[3‐(dimethylamino)propyl]‐N′‐(2‐oxidophenyl)oxamidato(3−)‐1:2κ2O,O′:κ4O′′,N,N′,N′′}copper(II)nickel(II) perchlorate

The title complex, [CuNi(C₁₃H₁₆N₃O₃)(C₁₀H₈N₂)₂(H₂O)]ClO₄, has a cis‐oxamide‐bridged heterobinuclear cation, with a Cu...Ni separation of 5.3297 (6) Å, counterbalanced by a disordered perchlorate anion. The Cu^II and Ni^II cations are located in square‐pyramidal and octahedral coordination environments, respectively. The complex molecules are assembled into a three‐dimensional supramolecular structure through hydrogen bonds and π–π stacking interactions. The influence of the two types of metal cation on the supramolecular structure is discussed.     

A three‐dimensional framework in 2,2′‐biimidazolium bis(2,2′‐biimidazole‐κ2N,N′)bis(biphenyl‐2,4′‐dicarboxylato‐κO)manganese(II) hexahydrate

In the title salt, (C₆H₈N₄)[Mn(C₁₄H₈O₄)₂(C₆H₆N₄)₂]·6H₂O, the Mn^II atom lies on an inversion centre and is coordinated by four N atoms from two 2,2′‐biimidazole (biim) ligands and two O atoms from two biphenyl‐2,4′‐dicarboxylate (bpdc) anions to give a slightly distorted octahedral coordination, while the cation lies about another inversion centre. Adjacent [Mn(bpdc)₂(biim)₂]²⁻ anions are linked via two pairs of N—H...O hydrogen bonds, leading to an infinite chain along the [100] direction. The protonated [H₂biim]²⁺ moiety acts as a charge‐compensating cation and space‐filling structural subunit. It bridges two [Mn(bpdc)₂(biim)₂]²⁻ anions through two pairs of N—H...O hydrogen bonds, constructing two R₂²(9) rings, leading to a zigzag chain in the [2] direction, which gives rise to a ruffled set of [H₂biim]²⁺[Mn(bpdc)₂(biim)₂]²⁻ moieties in the [01] plane. The water molecules give rise to a chain structure in which O—H...O hydrogen bonds generate a chain of alternating four‐ and six‐membered water–oxygen R₄²(8) and R₆⁶(12) rings, each lying about independent inversion centres giving rise to a chain along the [100] direction. Within the water chain, the (H₂O)₆ water rings are hydrogen bonded to two O atoms from two [Mn(bpdc)₂(biim)₂]²⁻ anions, giving rise to a three‐dimensional framework.     

Aquachlorobis(4,4′,4′′‐tri‐tert‐butyl‐2,2′;6′,2′′‐terpyridine‐κ3N)terbium(III) diperchlorate ethanol disolvate

In the title compound, [TbCl(C₂₇H₃₅N₃)₂(H₂O)](ClO₄)₂·2C₂H₆O, the Tb^III ion has a coordination number of eight, composed of two tridentate substituted‐ter­pyridine ligands, a water mol­ecule and a bound Cl^? anion. The first coordination shell can be described as a distorted bicapped trigonal prism. The dihedral angles between pyridine rings belonging to the same tpy ligand range from 5.2 (5) to 16.8 (5)°.     

μ‐2,2′,6,6′‐Tetramethyl‐4,4′‐bipyridine‐κ2N1:N1′‐bis[(diethylenetriamine‐κ3N,N′,N′′)palladium(II)] tetranitrate

The title compound, [Pd₂(C₄H₁₃N₃)₂(C₁₄H₁₆N₂)](NO₃)₄, comprises discrete tetracationic dumbbell‐type dinuclear complex molecules and noncoordinating nitrate anions. Two Pd(dien)²⁺ moieties (dien is diethylenetriamine) are joined by the rigid linear exo‐bidentate bridging 2,2′,6,6′‐tetramethyl‐4,4′‐bipyridine ligand to form the dinuclear complex, which lies across a centre of inversion in the space group P2₁/n, so that the rings in the 2,2′,6,6′‐tetramethyl‐4,4′‐bipyridine bridging ligand are parallel. In the crystal, the primary and secondary amino groups of the dien ligand act as hydrogen‐bond donors towards the nitrate anions to form a three‐dimensional hydrogen‐bond network.