A facile synthesis of (Z)-1, 6-disubstituted-7H-benzo[b][1,5]diazonin-7-one derivatives via arylation-allylation-RCM pathway of anthranilamide and isatoic anhydride

A facile and efficient method has been developed for the synthesis of (Z)-6-allyl-1-phenyl-1,2,5,6-tetrahydro-7H-benzo[b][1,5]diazonin-7-one and (Z)-1,6-diphenyl-1,2,5,6-tetrahydro-7H-benzo[b][1,5]diazonin-7-one from anthranilamide via N-arylation/N-allylation and from isatoic anhydride via ring opening/N-arylation/N-allylation followed by ring closing metathesis using Grubbs-II catalyst as a key step. Grubbs-II catalyst was found to be superior over Grubbs-I catalyst in terms of reaction time and yield of the product, and the routes developed were suitable to synthesize benzo fused nine membered nitrogen heterocycles. The requirement of diallylated substrates with protected amine and amide nitrogen is suitable for RCM has been established for the synthesis of diazoninone derivatives.     

Cu2O/1-(2-methylhydrazine-1-carbonyl)-isoquinoline 2-oxide catalyzed C-N cross-coupling reaction in aqueous media

An experimentally simple, efficient, and inexpensive catalyst system was developed for the N-arylation of imidazole, indole, pyrrole, alkyl alcohol amines, and alkyl amines with aryl iodides and bromides. The reaction proceeds in water-ethanol media at 120 °C for 12 h with Cu₂O as the catalyst, 1-(2-methylhydrazine-1-carbonyl)-isoquinoline 2-oxide (L2) as the ligand, NaOH as the base to generate a wide range of N-arylated products in moderate to excellent yields. Aqueous medium, ease of operation, and broad substrate scope give the process a benign environmental profile.     

(2,2′‐Bipyridyl‐κ2N,N′)­bis­(salicyl­ato‐κ2O,O′)­zinc(II)

The asymmetric unit of the title compound, [Zn(C₇H₅O₃)₂(C₁₀H₈N₂)], contains one monomeric zinc complex. The Zn atom is coordinated to one 2,2′‐bipyridyl ligand via both N atoms and to two salicyl­ate anions (Hsal⁻) in a bidentate chelating manner involving carboxyl­ate O‐atom coordination. The complex exhibits a distorted octahedral geometry about the Zn^II atom, with the `apical' positions occupied by one of the two N atoms of the bipyridyl ligand and an O atom from one Hsal<sup>−</sup> ligand; the Zn atom is 0.168 (1) Å out of the `basal' plane. Two intramolecular six‐membered hydrogen‐bonded rings are present, generated from interactions between the carboxyl and hydroxyl groups of the salicyl­ate ligands. The crystal packing is governed by weak C—H⋯O and C—H⋯π interactions.     

trans‐Di­aqua­bis(N‐acetyl­anthranilato‐O,O′)copper(II)

The title monomeric copper(II) complex, [Cu(C₉H₈NO₃)₂(H₂O)₂], (I), shows a square‐planar coordination and has an inversion centre at the Cu atom. The carboxyl­ate group of the N‐acetyl­anthranilate ion acts as a monodentate donor ligand to copper and as an acceptor of an intramolecular O—H?O hydrogen bond from the coordinated water mol­ecule, with an O?O distance of 2.581 (2) Å.     

trans‐Di­aqua­bis(6‐hydroxy­picolinato‐κ2N,O2)copper(II)

In the title compound, [Cu(C₆H₄NO₃)₂(H₂O)₂], the Cu^II ion lies on an inversion centre and has an elongated octahedral environment, equatorially trans‐coordinated by two N,O‐bidentate picolinate ligands and axially coordinated by two water O atoms. The complex mol­ecules form layers, which are linked by O—H⋯O hydrogen bonds between the aqua ligands and neighbouring carboxyl­ate groups. An intramolecular hydrogen bond between the coordinated carboxyl­ate O atom and the hydroxy H atom is also observed.     

A general method for regioselective Heck arylation of electron-rich N-acyl-N-vinylamine with aryl halides

A highly efficient protocol for the Pd-catalyzed regioselective Heck arylation of the electron-rich olefin N-acyl-N-vinylamine with aryl halides has been developed. In the presence of hydrogen-bond donor [H₂NiPr₂][BF₄] as an additive, this proceeds smoothly in isopropanol to afford exclusively the branched products in high yields.     

Tetrakis[(4‐aminopyridinio)acetato‐κO]diaquamanganese(II) diper­chlorate

In the centrosymmetric title complex, [Mn(C₇H₈N₂O₂)₄(H₂O)₂](ClO₄)₂, the Mn^II ion is in an octahedral environment, with the equatorial plane being defined by the O atoms of four monodentate carboxyl­ate groups, and the octahedron being completed by two trans‐coordinated water mol­ecules. There are intramolecular hydrogen bonds between the coordinated water mol­ecules and the non‐coordinated O atoms of the carboxyl­ate groups. Hydrogen bonds between the amino groups and the carboxyl­ate groups of neighbouring mol­ecules generate a layered hydrogen‐bonded network.     

Synthesis,structure and electrochemical properties of a family of organoruthenium complexes

Reaction of N-(2′-hydroxyphenyl)benzaldimines (abbreviated in general as H₂L-R, where R stands for the para-substituent in the benzaldehyde fragment and H stands for the dissociable hydrogen atoms) with [Ru(PPh₃)₂(CO)₂Cl₂] affords a family of organoruthenium complexes of the type [Ru(PPh₃)₂(CO)(L-R)] where the N-(2′-hydroxyphenyl)benzaldimine ligand is coordinated to the metal center as tridentate C,N,O-donor. Structure of a representative complex has been determined by X-ray crystallography. All the [Ru(PPh₃)₂(CO)(L-R)] complexes are diamagnetic, and show characteristic ¹H NMR signals and moderately intense MLCT transitions in the visible region. Cyclic voltammetry of the [Ru(PPh₃)₂(CO)(L-R)] complexes shows a reversible Ru(II)–Ru(III) oxidation within 0.38–0.68 V versus SCE, followed by an irreversible oxidation of the coordinated benzaldimine ligand within 1.09–1.27 V versus SCE. An irreversible reduction of the coordinated benzaldimine ligand is also observed near −1.1 V versus SCE. Potential of the Ru(II)–Ru(III) oxidation is observed to be sensitive to the nature of para-substituent R.     

A robust dimethylgold(III) complex stabilized by a 2-pyridyl-2-pyrrolide ligand

Reaction of isopropyl[(2-pyridyl)alkyl]amines such as N-isopropyl-N-2-methylpyridine or N-isopropyl-N-2-ethylpyridine with aqueous solutions of NaAuCl₄ led to the formation of [LAuCl₂][AuCl₄] in low yields, where L = pyridyl amine bound to gold in a bidentate fashion. Reaction of 2-(3,5-diphenyl-1H-pyrrol-2-yl)pyridine with aqueous NaAuCl₄, however, proceeded with formal loss of HCl and direct formation of the gold(III) amido complex L′AuCl₂, where L′ = deprotonated pyrrolyl ligand. Optimization of the reaction conditions to make the new amido complex identified MeCN:H₂O (1:2) as the best choice of solvent, affording product in 92% yield. This dichloro amido complex is a convenient precursor to L′AuMe₂, which was found to be air-stable and thermally robust.     

Diaqua­malonato(1,10‐phenanthro­line)­zinc(II)

In the crystal structure of the title complex, [Zn(C₃H₂O₄)(C₁₂H₈N₂)(H₂O)₂], the Zn^II atom displays a distorted octa­hedral geometry, being coordinated by two N atoms from the 1,10‐phenanthroline ligand, two O atoms from different carboxyl­ate groups of the chelating malonate dianion and two O atoms of cis water mol­ecules. The complex mol­ecules are linked to form a three‐dimensional supramolecular array by both hydrogen‐bonding inter­actions between coordinated water molecules and the uncoordinated carboxyl­ate O atoms of neighboring mol­ecules, and aromatic π–π stacking inter­actions between neighboring phenanthroline rings.     

The first bis(orotato–N,O) complex: Synthesis,crystal structure,spectroscopic and thermal characterization of (chaH)2[Cu(HOr–N,O)2(cha)] · 2H2O (cha = cyclohexylamine and HOr = orotate(2−))

The novel bis(cyclohexylaminium) cyclohexylaminebis(orotate–N,O)cuprate(II) dihydrate, (C₆H₁₅N)₂[Cu(C₅H₂N₂O₄)₂(C₆H₁₄N)] · 2H₂O, has been prepared and characterized by elemental analysis, magnetic measurements, FT-IR and UV–Vis spectroscopy, thermal analysis and X-ray diffraction. The Cu(II) complex crystallizes in the monoclinic space group P2₁/c. The copper atom in the five-coordinated (chaH)₂[Cu(HOr–N,O)₂(cha)] · 2H₂O is chelated by a deprotonated pyrimidine nitrogen atom and carboxylate oxygen atom as a bis(bidentate) ligand and the cyclohexylamine ligand completes the square-pyramidal coordination. The thermal decomposition of the complex has been predicted by the help of thermal analysis (TG, DTG and DTA).     

X-ray structure of fac-[RuH(1,5-cod)(NH2NMe2)3][PF6]: Stabilization of coordinated substituted hydrazines by hydrogen bonding

The structure of [RuH(cod)(NH₂NMe₂)₃][PF₆] has been solved by X-ray diffraction methods and shows the cation to contain a facial arrangement of N,N-dimethylhydrazine ligands, coordinated via the NH₂ nitrogen atoms, and held together by hydrogen bonds.     

catena‐Poly[[[cis‐aqua­bis(4‐carboxy­cyclo­hexane‐1‐carboxyl­ato‐κ2O,O′)cadmium(II)]‐μ‐4,4′‐bipyridine‐κ2N:N] monohydrate]

The title complex, {[Cd(C₈H₁₁O₄)₂(C₁₀H₈N₂)(H₂O)]·H₂O}_n, consists of linear chains formed through 4,4′‐bipyridine ligands linking seven‐coordinated Cd^II ions. Each Cd^II ion is in a distorted penta­gonal–bipyramidal environment, coordinated by one water ligand, two 4‐carboxy­cyclo­hexane‐1‐carboxyl­ate ligands and one bridging 4,4′‐bipyridine ligand to generate linear chains. The water mol­ecules and the Cd atom on one side, and the 4,4′‐bipyridine unit on the other, are bisected by two sets of twofold axes. The carboxylate group of the 4‐carboxy­cyclo­hexane‐1‐carboxyl ligand chelates a Cd^II ion, while the (protonated) carboxyl group forms hydrogen bonds with adjacent chains, resulting in a layered structure. This is the first reported occurrence of a dicarboxycyclo­hexane ligand exhibiting a non‐bridging coordination mode.     

Electronic structure and vibrational spectra of cis-diammine(orotato)platinum(II), a potential cisplatin analogue: DFT and experimental study

Orotic acid (vitamin B₁₃) is a key intermediate in biosynthesis of the pyrimidine nucleotides in living organisms, moreover, it may serve as the biological carrier for some metal ions. cis-Diammine(orotato)platinum(II), cis-[Pt(C₅H₂N₂O₄)(NH₃)₂] can be considered as a new potential cisplatin analogue. The FT-Raman and FT-IR spectra of the title complex are reported, for the first time. The molecular structure, vibrational frequencies, and the theoretical infrared and Raman intensities have been calculated by the density functional mPW1PW91 method. The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution. The theoretically predicted IR and Raman spectra show very good agreement with experiment. Natural bond orbital (NBO) analyses were performed for cisplatin, carboplatin and the title complex. The results provided new data on the nature of platinum–ligand bonding in these compounds. Strong intramolecular hydrogen bond between the orotate ligand and the coordinated ammonia group stabilizes the structure of the platinum(II) complex. Thus, it is suggested that the orotate ligand in the title complex is more inert to the substitution reactions than the chloride ligands in cisplatin.     

μ‐1,2‐Bis(4‐pyridyl)ethene‐κ2N:N′‐bis(tetraaqua­{4‐[2‐(4‐pyridinio)­ethenyl]pyridine‐κN}cobalt(II)) hexaaqua­cobalt(II) tetrakis(sulfate) octahydrate

The title compound, [Co₂(C₁₂H₁₁N₂)₂(C₁₂H₁₀N₂)(H₂O)₈][Co(H₂O)₆](SO₄)₄·8H₂O, consists of bis(4‐pyridyl)ethenedicobalt(II) cations, hexaaqua­cobalt cations, sulfate anions and water solvent molecules that are linked by hydrogen bonds into a network structure. In the hexaaquacobalt cation, the six water molecules are coordinated in an octahedral geometry to the Co atom, which lies on an inversion centre. The other cation is a 1,2‐bis(4‐pyridyl)ethene‐bridged centrosymmetric dimer, consisting of protonated 1,2‐bis(4‐pyridyl)­ethene cations, a bridging 1,2‐bis(4‐pyridyl)ethene ligand and tetraaqua­cobalt cations. Each Co atom is six‐coordinated by four water molecules and two N atoms from a protonated 1,2‐bis(4‐pyridyl)ethene cation and the bridging 1,2‐bis(4‐pyridyl)­ethene ligand, and the geometry around each Co atom is octahedral.     

Synthesis,crystal structure and catalytic activity of an oxo-diperoxo tungsten(VI) complex containing an oxazine ligand for selective oxidation of sulfides

Abstract

A novel oxo-diperoxo tungsten(VI) complex, [WO(O₂)₂(Hphox)], was prepared by reaction of WO₃ in H₂O₂ with an oxazine-type ligand, 2-(2′-hydroxylphenyl)oxazine (Hphox). The complex was characterized by FTIR, ¹H NMR and elemental analysis. The single-crystal X-ray diffraction studies revealed a seven-coordinate tungsten center with a distorted octahedral geometry. The [WO(O₂)₂(Hphox)] complex was applied as a catalyst in efficient and selective oxidation of sulfide to sulfoxide using 30% H₂O₂ or UHP (urea hydrogen peroxide) as oxidants. This catalyst showed excellent catalytic activities and high selectivities in producing a variety of aryl and alkyl sulfoxides under mild conditions. To get an insight into the mechanisms of oxidation of sulfides, the mechanistic studies were monitored by UV–Vis spectroscopy.     

Catalytic efficacy of Schiff-base copper(II) complexes: Synthesis,X-ray structure and olefin oxidation

Three copper(II) Schiff-base complexes, [Cu(L¹)(H₂O)](ClO₄) (1), [Cu(L²)] (2) and [Cu(L³)] (3) have been synthesized and characterized [where HL¹ = 1-(N-ortho-hydroxy-acetophenimine)-2-methyl-pyridine], H₂L² = N,N′-(2-hydroxy-propane-1,3-diyl)-bis-salicylideneimine and H₂L³ = N,N′-(2,2-dimethyl-propane-1,3-diyl)-bis-salicylideneimine]. The structure of complex 1 has been determined by single crystal X-ray diffraction analysis. In complex 1, the copper(II) ion is coordinated to one oxygen atom and two nitrogen atoms of the tridentate Schiff-base ligand, HL¹. The fourth coordination site of the central metal ion is occupied by the oxygen atom from a water molecule. All the complexes exhibit high catalytic activity in the oxidation reactions of a variety of olefins with tert-butyl-hydroperoxide in acetonitrile. The catalytic efficacy of the copper(II) complexes towards olefin oxidation reactions has been studied in different solvent media.     

Early Main Group Metal Catalysis: How Important is the Metal?

Organocalcium compounds have been reported as efficient catalysts for various alkene transformations. In contrast to transition metal catalysis, the alkenes are not activated by metal–alkene orbital interactions. Instead it is proposed that alkene activation proceeds through an electrostatic interaction with a Lewis acidic Ca²⁺. The role of the metal was evaluated by a study using the metal‐free catalysts: [Ph₂N^?][Me₄N⁺] and [Ph₃C^?][Me₄N⁺]. These “naked” amides and carbanions can act as catalysts in the conversion of activated double bonds (C?O and C?N) in the hydroamination of Ar? N?C?O and R? N?C?N? R (R=alkyl) by Ph₂NH. For the intramolecular hydroamination of unactivated C?C bonds in H₂C?CHCH₂CPh₂CH₂NH₂ the presence of a metal cation is crucial. A new type of hybrid catalyst consisting of a strong organic Schwesinger base and a simple metal salt can act as catalyst for the intramolecular alkene hydroamination. The influence of the cation in catalysis is further evaluated by a DFT study.     

Early Main Group Metal Catalysis: How Important is the Metal?

Organocalcium compounds have been reported as efficient catalysts for various alkene transformations. In contrast to transition metal catalysis, the alkenes are not activated by metal–alkene orbital interactions. Instead it is proposed that alkene activation proceeds through an electrostatic interaction with a Lewis acidic Ca²⁺. The role of the metal was evaluated by a study using the metal‐free catalysts: [Ph₂N⁻][Me₄N⁺] and [Ph₃C⁻][Me₄N⁺]. These “naked” amides and carbanions can act as catalysts in the conversion of activated double bonds (CO and CN) in the hydroamination of Ar NCO and R NCN R (R=alkyl) by Ph₂NH. For the intramolecular hydroamination of unactivated CC bonds in H₂CCHCH₂CPh₂CH₂NH₂ the presence of a metal cation is crucial. A new type of hybrid catalyst consisting of a strong organic Schwesinger base and a simple metal salt can act as catalyst for the intramolecular alkene hydroamination. The influence of the cation in catalysis is further evaluated by a DFT study.     

Polymerization reactions in [Co(NH3)5(H2O)][CoX(CN)5] and cis-[Co(NH3)4(H2O)2][CoX(CN)5] (X = Cl,Br, I,No2 OR N3) double-complex salts

Polymerization reactions of [Co(NH₃)₅(H₂O)][CoX(CN)₅] and cis-[Co(NH₃)₄ (H₂O)₂][CoX(CN)₅] (X = Cl, Br, I, NO₂ or N₃] have been studied. The compounds undergo aging reactions in the solid state or in solution induced by the ligand X involving solvolytic processes affording polymeric materials with μ-cyano bridges. A mechanistic explanation of these reactions is given and a comparison between both series of compounds together with the parent compound [Co(NH₃)₆][Co(CN)₆] is discussed.