Aqua(2,2′‐bipyrid­yl)­chloro­nitrato­copper(II)

In a new hydrogen‐bonded three‐dimensional complex, [CuCl(NO₃)(C₁₀H₈N₂)(H₂O)], the Cu atom has an elongated tetra­gonal octa­hedral environment, with two 2,2′‐bipyridyl N atoms, one nitrate O atom and one Cl atom forming the equatorial plane, and a second O atom of the nitrate anion and a water mol­ecule in the axial positions. The complex mol­ecules are linked to form a three‐dimensional supra­molecular array by hydrogen‐bonding inter­actions both between the water O atom and nitrate O atoms, and between the water O atom and the Cl atom of a neighboring mol­ecule.     

Synthesis of tripodal aza crown ether calix[4]arenes and their supramolecular chemistry with transition-, alkali metal ions and anions

Tripodal aza crown ether calix[4]arenes, 5a, 5b, 6a and 6b, have been synthesized. The structure of protonated 5a was elucidated by X-ray crystallography to be a self-threaded rotaxane. Complexation studies of 5a and 5b towards anions using Na⁺ as countercation were carried out by ¹H NMR titration in dimethylsulfoxide-d₆ and the mixture of chloroform-d and methanol-d₄, respectively. Ligands 5a and 5b were able to form 1:1 complexes with Br⁻, I⁻ and NO₃⁻ and the complexation stability varied as follows: NO₃⁻>I⁻>Br⁻. The effect of countercation on anion complexation was also investigated. The results showed that the association constants of 5a towards Br⁻ in the presence of various cations varied as K⁺>Bu₄N⁺>Na⁺. The enhancement in anion complexation ability of 5a may result from the rearrangement of the tripodal ammonium unit in the presence of K⁺. The neutral forms, 6a and 6b, were able to form complexes with transition metal ions such as Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺. The stability of the complexes followed the sequence: Ni²⁺2+Cu²⁺Zn²⁺. Compounds 6a and 6b may, therefore, potentially be used as either transition metal ion or anion receptors that can be controlled by pH of the solution.     

Co-crystal Structure of 11-Hydroxy-2,3,9-trimethoxy-6<Emphasis Type="Italic">H</Emphasis>-chromeno[3,4-<Emphasis Type="Italic">b</Emphasis>]chromen-12-one and 11-Hydroxy-2,3,9-trimethoxy-chromeno[3,4-<Emphasis Type="Italic">b</Emphasis>]chromene-6,12-dione

Abstract  

A 1:1 co-crystal structure of 11-hydroxy-2,3,9-trimethoxy-6H-chromeno[3,4-b]chromen-12-one and 11-hydroxy-2,3,9-trimethoxy-chromeno[3,4-b]chromene-6,12-dione (stemonone) was crystallized from the reaction mixture of 6-deoxyclitoriacetal and methanesulfonyl chloride, and its structure was characterized by X-ray diffraction. This co-crystal crystallizes in a triclinic crystal system, space group P(−1) with unit cell parameters of a = 8.1317(3) Å, b = 9.8224(4) Å, c = 10.7268(3) Å, α = 78.116(1)°, β = 77.463(1)°, γ = 77.140(1)°, Z = 2 and V = 804.11(3) Å³. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F ² to final values of R ₁ = 0.0501 and wR ₂ = 0.1520.     

New ferromagnetic dinuclear triply-bridged copper(II) compounds containing carboxylato bridges: Synthesis,X-ray structure and magnetic properties

The new triply-bridged dinuclear copper(II) complexes, [Cu₂(μ-O₂CH)(μ-OH)₂(dpyam)₂](ClO₄) · H₂O (1), [Cu₂(μ-O₂CCH₃)(μ-OH)(μ-OH₂)(dpyam)₂](S₂O₈) (2), [Cu₂(μ-O₂CCH₃)(μ-OH)(μ-OH₂)(bpy)₂](NO₃)₂ (3), [Cu₂(μ-O₂CCH₃)(μ-OH)(μ-OH₂)(phen)₂](BF₄)₂ · 0.5H₂O (4), [Cu₂(μ-O₂CCH₂CH₃)(μ-OH)(μ-OH₂)(phen)₂](NO₃)₂ (5) and [Cu₂(μ-O₂CCH₃)(μ-OH)(μ-Cl)(bpy)₂]Cl · 8.5H₂O (6) (dpyam = di-2-pyridylamine, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and characterized crystallographically and also their spectroscopic and magnetic properties have been studied. A structural classification of this type of dimers, based on the data obtained from X-ray diffraction analysis in the present work and those reported in the literature has been performed. In these complexes, the local geometry around the copper centre is generally a distorted square pyramid and distorted trigonal bipyramid with different degrees of distortion. The global geometry of the dinuclear complexes can be described in terms of the relative arrangement of the two five-coordinate environments, giving rise to different classes (A–F) of complexes. The most logical explanations have been provided for each class describing different magnetic interactions. Practically, there is a clear correlation between structural data and J values of the class B complexes. Extended Hückel calculations were performed for the present complexes 1–6, as well as for some other class B complexes, showing the different molecular orbitals involved in their corresponding frontier orbitals, together with their energy. The results are found to be useful for the proper interpretation and correlation of the magnetic data and the dinuclear structure of the present complexes.     

Three new polynuclear tetracarboxylato-bridged copper(II) complexes: Syntheses, X-ray structure and magnetic properties

The synthesis, crystal structure and magnetic measurements of three new polynuclear tetracarboxylato-bridged copper(II) complexes, i.e. {[Cu₄(phen)₂(μ-O₂CC₂H₅)₈] · (H₂O)}_n (1), [Cu₂(μ-O₂CC₆H₄OH)₄(C₇H₇NO)₂] · 6H₂O (2) and [Cu₂(μ-O₂CCH₃)₄(C₇H₇NO)₂] (3) (phen = 1,10-phenanthroline, O₂CC₆H₄OH = 3-hydroxy benzoate, C₇H₇NO = 4-acetylpyridine) are reported. All compounds consist of dinuclear units, in which two Cu(II) ions are bridged by four syn,syn-η¹:η¹:μ carboxylates, showing a paddle-wheel cage type with a square-pyramidal geometry, arranged in different ways. The structure of compound 1 consists of an one-dimensional structure generated by an alternating classical dinuclear paddle-wheel unit and an unusual dinuclear Cu₂(μ-OCOC₂H₅)₂(μ-O₂CC₂H₅)₂(phen)₂unit, which are connected to each other via a syn,anti-triatomic propionato bridge in an axial-equatorial configuration. The adjacent chains are connected to generate a 2D structure through the face-to-face π–π interaction between phen rings. Structures of compounds 2 and 3 both consist of a symmetric dinuclear Cu(II) carboxylate paddle-wheel core and pyridyl nitrogen atoms of 4-acetylpyridine ligand at the apical position, and just differ in the substituents of the equatorial ligands.

The magnetic properties have been measured and correlated with the molecular structures. It is found that in the two classical paddle-wheel compounds the Cu(II) ions are strongly antiferromagnetically coupled with J = −278.5 and −287.0 cm⁻¹ for complexes 2 and 3, respectively. In compound 1 the magnetic susceptibility could be fitted with two different, independent Cu(II) units, one strongly coupled and one weakly coupled; the paddle-wheel dinuclear unit has the strongest antiferromagetic coupling with a value for J of −299.5 cm⁻¹, whereas the Cu(II) ions in the propionato-bridged dinuclear unit of 1 display a very weak antiferromagnetic coupling with a value for J = −0.75 cm⁻¹, due to the orthogonality of the magnetic orbitals. Also the exchange within the chain is therefore very weak. The magneto-structural correlations for complexes 1, 2, and 3 are discussed on the basis of the structural parameters and magnetic data for the complexes.     

Convenient synthetic route to a dehydrorotenoid via selective intramolecular aldol condensation of 1,2-diaryl diketone

Synthesis of dehydrorotenoid (1) was successfully achieved via an intramolecular aldol reaction of the corresponding 1,2-diaryl diketone intermediate. The 1,2-diaryl diketone was prepared using a ruthenium-catalyzed oxidation of the corresponding substituted diaryl acetylene. Treatment of this 1,2-diketone with l-proline induced a selective intramolecular aldol condensation reaction, forming the desired benzopyranone over the alternative benzofuran. Deprotection, cyclization, and dehydration gave the target compound in good overall yield.     

Hydrogen bonding in labdane diterpenoids, labda-7,12(E),14-triene-17-oic acid and labda-12(Z),14,17-triene-18-oic acid

Two labdane diterpenoids, labda-7,12(E),14-triene-17-oic acid (1) and labda-12(Z),14,17-triene-18-oic acid (2), C₂₀H₃₀O₂, have been isolated from Croton oblongifolius. Both 1 and 2 crystallized in the monoclinic system, space group C2, with cell dimensions of a = 21.912(1) Å, b = 7.4002(4) Å, c = 11.5079(7) Å, = 101.999(1)^o and a = 21.308(2) Å, b = 11.9067(9) Å, c = 7.5606(6) Å, = 100.763(1)^o, respectively. Compound 1, a rare example of carboxylic group bound to a cyclohexene ring, forms an infinite intermolecular hydrogen-bonded polymer [O1 O2(–x + 1/2, y + 1/2, –z + 2) 2.697(2) Å], whereas molecules of compound 2 are linked to form an asymmetric hydrogen-bonded dimer [O1 O2(–x, y, –z) 2.657(3) Å].     

μ‐Acetato‐1:2κ2O:O′‐diacetato‐1κ2O,O′;2κO‐bis(di‐2‐pyridylamine)‐1κ2N,N′;2κ2N,N′‐isothiocyanato‐2κN‐dicopper(II)

In the title dinuclear acetate‐bridged complex, [Cu₂(C₂H₃O₂)₃(NCS)(C₁₀H₉N₃)₂], the two Cu atoms are five‐coordinated, with a basal plane consisting of two N atoms of a di‐2‐pyridylamine (dpyam) ligand and two O atoms of two different acetate ligands. The axial positions of these Cu atoms are coordinated to N and O atoms from thio­cyanate and acetate mol­ecules, respectively, leading to a distorted square‐pyramidal geometry with τ values of 0.30 and 0.22. Both Cu^II ions are linked by an acetate group in the equatorial–equatorial positions and have syn–anti bridging configurations. Hydrogen‐bond inter­actions between the amine H atom and the coordinated and uncoordinated O atoms of the acetate anions generate an infinite one‐dimensional chain.