4‐[(2‐Chloro­phenyl)­diazenyl]‐6‐methoxy‐2‐{[tris­(hydroxy­methyl)­methyl]­amino­methyl­ene}cyclo­hexa‐3,5‐dien‐1(2H)‐one

The structure of the title compound, C₁₈H₂₀ClN₃O₅, displays the characteristic features of azo­benzene derivatives. Intramolecular N—H⋯O, weak intramolecular C—H⋯O, and intermolecular O—H⋯O and C—H⋯O interactions influence the conformation of the mol­ecules and the crystal packing. Intermolecular hydrogen bonds link the mol­ecules into infinite chains, and the title compound adopts the keto–amine tautomeric form. The azo­benzene moiety of the mol­ecule has a trans configuration. The mol­ecule is not planar, and the dihedral angle between the two phenyl rings is 35.6 (2)°.     

4‐[(3‐Chloro­phenyl)­diazenyl]‐2‐{[tris(hydroxy­methyl)­methyl]amino­methyl­ene}cyclo­hexa‐3,5‐dien‐1(2H)‐one

The title compound, C₁₇H₁₈ClN₃O₄, adopts the keto–amine tautomeric form and displays an intramolecular N—H⋯O hydrogen bond [N⋯O = 2.639 (2) Å]. The configuration around the azo N=N double bond is trans, and the dihedral angle between the planes of the two aromatic rings is 20.5 (2)°. The mol­ecules are linked by O—H⋯O hydrogen bonds to form a three‐dimensional network.     

3‐Methoxy‐5‐(4‐methyl­phenyl­diazenyl)­salicyl­aldehyde and 3‐methoxy‐5‐(2‐methyl­phenyl­diazenyl)­salicyl­aldehyde

The two title mol­ecules, both C₁₅H₁₄N₂O₃, are roughly planar and display a trans conformation with respect to the –N=N– double bond, as found for other diazene derivatives. In both compounds, there are intramolecular O—H⋯O hydrogen bonds and the crystal packing is governed by weak intermolecular C—H⋯O hydrogen bonds and π–π stacking.     

3‐Hydro­xy‐6‐[(4‐hydroxy­phenyl­amino)­methyl­ene]­cyclo­hexa‐2,4‐dienone and 2‐hydroxy‐6‐[(4‐hydroxy­phenyl­amino)­methyl­ene]­cyclo­hexa‐2,4‐dienone

The title compounds, both C₁₃H₁₁NO₃, exist as the keto–amine tautomers, and the formal hydroxyl H atoms, which display strong intramolecular hydrogen bonds, are located on the N atoms. This is a verification of the preference for the keto–amine tautomeric form in the solid state. The 2‐hydroxy isomer has two independent mol­ecules, with the mol­ecules linked by intramolecular N—H⋯O and O—H⋯O and intermolecular O—H⋯O hydrogen bonds into three‐dimensional networks.     

2‐[(2‐Hydro­xy‐4‐nitro­phenyl)­amino­methyl­ene]­cyclo­hexa‐3,5‐dien‐1(2H)‐one

The title compound, C₁₃H₁₀N₂O₄, adopts the keto–amine tautomeric form and displays an intramolecular N—H⋯O [N⋯O = 2.579 (2) Å] and three intermolecular O—H⋯O [O⋯O = 2.561 (2) Å] and C—H⋯O [C⋯O = 3.274 (2) and 3.318 (2) Å] hydrogen bonds. The keto–amine structure is favoured by through‐mol­ecule conjugation between the hydroxy O atom and imine N atom. The dihedral angle between the planes of the two aromatic rings is 10.79 (4)°.     

(Z)‐6‐{[1,3‐Dihydroxy‐2‐(hydroxy­methyl)propan‐2‐ylamino]methyl­ene}‐2‐methoxy‐4‐[(E)‐o‐tolyl­diazenyl]­cyclo­hexa‐2,4‐dienone

The title compound, C₁₉H₂₃N₃O₅, adopts the keto–amine tautomeric form with the hydr­oxy H atom located on the N atom, where it is involved in a strong intra­molecular N—H⋯O hydrogen bond. The compound exhibits trans geometry with respect to the azo N=N double bond, with a dihedral angle between the two benzene rings of 38.03 (6)°. The packing of the mol­ecules in the crystal structure is determined by O—H⋯O and C—H⋯O hydrogen bonds. A comparison with closely related compounds is given.     

2‐(Phenyl­amino­methyl­idene)­cyclo­hexane‐1,3‐dione

In the title compound, C₁₃H₁₃NO₂, there is polarization of π‐electron density from the amine N atom to the acceptor carbonyl groups: as a result, the mol­ecule exists predominantly in an azomethino‐1,3‐diketone tautomeric form. There is crystallographic evidence that the phenyl ring, although roughly coplanar with the rest of the mol­ecule, is deconjugated with the adjacent π system of the mol­ecule. The cyclo­hexane ring adopts an unsymmetrical half‐chair conformation and converts between two inversion‐related conformers. The mol­ecule is stabilized by an intramolecular hydrogen bond, while the intermolecular packing is dominated by a number of short C—H⋯O contacts.     

3,5‐Di­methyl‐4‐(2,4,6‐tri­methyl­phenyl­diazenyl)­phenol

In the title compound, C₁₇H₂₀N₂O, (I), the dihedral angle between the two phenyl rings is 15.69 (6)°. An intermolecular hydrogen‐bonding association exists between the hydroxy group and one of the azo N atoms.     

Di­methyl 2‐{[2‐(methoxy­carbonyl)‐1‐(methoxy­carbonyl­methyl)pyrrol‐4‐yl]­methyl­ene}propane­dioate

The title compound, C₁₅H₁₇NO₈, is a pyrrole–ethene derivative with potential biological activity. Although a large part of the mol­ecule is planar, there is no structural evidence for any conjugation push–pull effect across the ethyl­enic bond, which is usually observed for substituted ethyl­enes; π‐electron delocalization appears to be restricted to the 2‐(methoxy­carbonyl)­pyrrole moiety.     

[2‐(Anilino­methyl)­phenyl]­di­phenyl­phosphine and {2‐[(N‐methyl­anilino)­methyl]­phenyl}di­phenyl­phosphine

The title compounds, Ph₂PCH₂N(H)Ph or C₂₅H₂₂NP and Ph₂PCH₂N(CH₃)Ph or C₂₆H₂₄NP, respectively, are isomorphous, with calculated theoretical Tolman angles of 174 and 182°.     

cis‐Di­chloro­(di­methyl­aminomethyl­ene)­(tri­phenyl­phosphine)palladium(II) acetone solvate

The synthesis and X‐ray structural analysis of the title compound, [PdCl₂(C₃H₇N)(C₁₈H₁₅P)]·C₃H₆O, are described. The crystal structure contains discrete monomeric mol­ecules of the carbene complex and solvent mol­ecules separated by normal van der Waals distances. The Pd atom is four‐coordinate in an essentially square‐planar environment, with the chlorine ligands mutually cis; Pd—P = 2.2495 (7), Pd—Cl = 2.3508 (7) and 2.3600 (7), Pd—C 1.948 (2) and N—C(carbene) 1.274 (3) Å.     

1‐(4‐Chloro­phenyl­sulfanyl)‐2‐nitro‐4‐(tri­fluoro­methyl)­benzene and 1‐(4‐chloro­phenyl­sulfanyl)‐4‐nitro‐2‐(tri­fluoro­methyl)­benzene

Two chemical isomers of 3‐nitro­benzotrifluoride, namely 1‐(4‐chloro­phenyl­sulfanyl)‐2‐nitro‐4‐(tri­fluoro­methyl)­benzene, C₁₃H₇ClF₃NO₂S, (I), and 1‐(4‐chloro­phenyl­sulfanyl)‐4‐nitro‐2‐(tri­fluoro­methyl)­benzene, C₁₃H₇ClF₃NO₂S, (II), have been prepared and their crystal structures determined with the specific purpose of forming a cocrystal of the two. The two compounds display a similar conformation, with dihedral angles between the benzene rings of 83.1 (1) and 76.2 (1)°, respectively, but (I) packs in P while (II) packs in P2₁/c, with C—H⋯O interactions. No cocrystal could be formed, and it is suggested that the C—H⋯O associations in (II) prevent intermolecular mixing and promote phase separation.     

Potassium N‐(6‐oxo­cyclo­hexa‐1,3‐dien‐5‐yl­idene­methyl)­glycinate

We are very interested in characterizing ligands derived from salicyl­aldehyde and α‐amino acids. These ligands form interesting complexes with different transition metals, which are very useful for understanding some biological systems. For Schiff bases derived from salicyl­aldehyde and different alkyl­amines or aryl­amines, the enol–imine form is predominant. The title compound, (I), shows bond distances which are clearly in agreement with the keto–amine form.     

2‐[Benzoyl­(hydroxy­imino)­methyl­amino]­benzoic acid

The structure of the title compound, C₁₅H₁₂N₂O₄, consists of a polymeric arrangement, around inversion centres, of mol­ecules linked through O—H⋯N and O—H⋯O hydrogen bonds; there are also intramolecular hydrogen bonds. All these hydrogen‐bond interactions result in the formation of infinite chains parallel to the [010] direction. The oxime group has an E conformation.     

trans‐Chloro­(methyl)­bis­(tri­cyclo­hexyl­phosphine)­platinum(II)

The crystal structure of the title compound, [PtCl(CH₃)(C₁₈H₃₃P)₂], is isostructural with various platinum(II) and palladium(II) complexes containing two bulky tri­cyclo­hexyl­phosphine ligands in a trans orientation. The Pt atom resides on an inversion centre, resulting in a 50% statistical disorder in the chloro and methyl positions. The most significant geometrical parameters are Pt—P 2.3431 (8), Pt—­Cl 2.440 (4) and Pt—C1 2.179 (13) Å, and P—Pt—P 180, P—Pt—Cl 89.15 (12) and 90.85 (12), and C—Pt—Cl 172.7 (5)°. The effective and Tolman cone angles for the tricyclohexylphosphine ligands were calculated as 160 and 162°, respectively.     

1,3,5‐Tris­(chloro­methyl)­benzene

The title compound, C₉H₉Cl₃, is being used as a platform for new tripodal receptors. Two mol­ecules make up the asymmetric unit; weak intermolecular hydrogen bonding is observed between methyl­ene H atoms and the chlorine of an adjacent mol­ecule. There are also C—H?π interactions.     

Di­methyl(2‐methyl­phenyl)­ammonium hydroxo­tris­(penta­fluoro­phenyl)­borate

In the title compound, [(CH₃)₂(C₇H₇)NH][(C₆F₅)₃B(OH)] or C₉H₁₄N⁺·C₁₈HBF₁₅O^?, the distorted tetrahedral borate anions are strongly hydrogen bonded to the substituted ammonium cations. The N?O separation in the N—H?O hydrogen bond is 2.728 (3) Å.     

2,6‐Di­methyl‐4‐(phenyl­diazenyl)­phenol

The crystal structure of the title compound, C₁₄H₁₄N₂O, determined at 293 K, shows that the mol­ecule is approximately planar in the solid state and that the aromatic rings have a trans configuration with respect to the azo double bond, as found for other diazene derivatives. The packing can be described as a polymeric arrangement of mol­ecules linked through O—H⋯N and C—H⋯O hydrogen bonds and close contacts. These intermolecular interactions result in the formation of infinite chains parallel to the b axis.     

Chloro(2‐{[5‐(2‐hydroxy­benzyl‐O)‐1,5‐di­aza‐1‐cyclo­octyl‐N,N′]­methyl}phenolato‐O)­cadmium(II)

The crystal structure of the title complex, [Cd(C₂₀H₂₅­N₂­O₂)­Cl], reveals a hydrogen‐bonded dimer composed of neutral molecules. The Cd^II center is five‐coordinated by two O atoms of the pendant arms, two nitro­gen donors of the 1,5‐di­aza­cyclo­octane ring and a chloride anion. The coordination geometry of the complex could be described as a distorted square pyramid. The 1,5‐di­aza­cyclo­octane backbone adopts a boat/chair configuration and the two phenol/phenolato groups have a dihedral angle of 101.3 (2)° between them. The coordinated phenolate and phenolic groups of inversion‐related mol­ecules form strong intermolecular O—H?O hydrogen bonds.     

4,4′‐(Azino­di­methyl­ene)­dipyridinium chloranilate di­chloro­methane disolvate

The di­chloro­methane disolvate of 4,4′‐(azino­di­methyl­ene)­dipyridinium chloranilate, C₁₂H₁₂N₄²⁺·C₆Cl₂O₄²⁻·2CH₂Cl₂, con­sists of one‐dimensional hydrogen‐bonded molecular tapes that propagate along the [10] direction. Both cations and anions lie across centres of inversion. The molecular tapes are planar but do not stack in the expected segregated manner, instead having chloranilate anions sandwiched between azine groups.