A highly efficient and ecofriendly procedure for tetrahydropyranylation of alcohols and phenols in the presence of in-situ generated I2 under heterogeneous and neutral conditions

Abstract  Molecular iodine generated in situ from Fe(NO₃)₃·9H₂O/NaI acts as a highly efficient catalyst for tetrahydropyranylation of various alcohols and phenols with 3,4-dihydro-2H-pyran in almost quantitative yields. The reaction occurs rapidly in dichloromethane at room temperature, and use of toxic molecular iodine is avoided. Graphical Abstract        

Very fast and efficient synthesis of some novel substituted 2-arylbenzimidazoles in water using ZrOCl2·nH2O on montmorillonite K10 as catalyst

Abstract  A simple and eco-friendly protocol for the synthesis of some novel substituted 2-arylbenzimidazoles was developed. In this process, these compounds were prepared in water as the solvent using ZrOCl₂·nH₂O supported on montmorillonite K10 as an efficient water tolerating Lewis acid. The reaction was performed under mild conditions with good to excellent yields and remarkable chemoselectivity in the absence of any byproduct. Graphical Abstract        

Crystallographic and theoretical studies of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid (1/1) with intermolecular O–H···N hydrogen bonds and S···O heteroatom interactions

Abstract  The molecular and crystal structure of a 1:1 co-crystal of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid, (1), has been determined by X-ray diffraction at the monoclinic space group P2₁/c with cell parameters of a = 8.422(6), b = 7.343(4), c = 16.112(7) ?, β = 104.988(8)°, V = 962.5(10) ?³ and Z = 2. In the crystal structure, two components connect via the intermolecular O–H···N hydrogen bonds [2.804(4) ?] and S···O heteroatom interaction [2.945(3) ?] with R ₂ ²(7) couplings to form a unique and infinite one-dimensional supramolecular tape structure. The calculations of (1) at the HF/6-31G(d), MP2/6-31G(d), and B3LYP/6-31G(d) levels can almost reproduce X-ray geometry. In addition, the distances of the intermolecular O–H···N and S···O interactions by MP2/6-31G(d) and B3LYP/6-31G(d) levels agree well with those in the crystal. The calculated binding energies corrected BSSE and ZPE are −4.487 (HF), −7.473 (MP2), and −5.640 (B3LYP) kcal/mol. The results suggest that the complex (1) is very stable and the dispersion interaction is significantly important for the attractive intermolecular interaction in (1). The NBO analysis has revealed that the n(N) → σ*(O–H) interaction gives the strongest stabilization to the system and the major interaction for the intermolecular S···O contact is n(O) → σ*(S–N). Index Abstract  In the crystal structure of the title compound, the molecules are linked by intermolecular O–H···N hydrogen bonds and short S···O heteroatom interactions with R ₂ ²(7) couplings to construct a unique and infinite one-dimensional supramolecular tape structure.      

Crystal structural characterization of three chlorosalicylato titanocene compounds

Abstract  Three chlorosalicylato titanocene compounds, namely [(MeCp)₂Ti(O,O′)(OCC₆H₃-5-Cl)]₂ (1), [(MeCp)₂Ti(O,O′)(OCC₆H₂-3,5-Cl₂)] (2) and [(MeCp)₂Ti(O,O′)(OCC₆H-3,5,6-Cl₃)] (3) have been synthesized via the reaction of (MeCp)₂TiCl₂ [MeCp = η⁵-(CH₃)C₅H₄] with the corresponding substituted chlorosalicylic acids in aqueous-organic systems in high yields and characterized by elemental analysis, IR and ¹H NMR spectra. Single-crystal X-ray diffraction analysis shows that geometries at titanium (IV) atoms are distorted tetrahedrons and the exhibited frameworks are constructed through weak interactions, which are H-bonding, π–π stacking and C–H···π interactions. Additional weak interactions, such as Cl···Cl interactions in compound 1, are also present, which help to form and stabilize crystalline materials. It is noticeable that the discriminating framework structures of three compounds due to their weak interactions existing conspicuous changes which result from the number of chlorine atoms on substituted chlorosalicylates. Graphical Abstract  Three to four coordinated chlorosalicylato titanocene compounds, [(MeCp)₂Ti(O,O′)(OCC₆H₃-5-Cl)]₂ (1), [(MeCp)₂Ti(O,O′)(OCC₆H₂-3,5-Cl₂)] (2) and [(MeCp)₂Ti(O,O′)(OCC₆H-3,5,6-Cl₃)] (3) have been synthesized in aqueous-organic system in high yields. Single-crystal X-ray diffraction analysis shows that geometries at titanium (IV) atoms are distorted tetrahedrons and the exhibited frameworks are constructed through weak interactions. The number of chlorine atoms on substituted chlorosalicylates has an effect on their framework structures.      

α-[Mn(O2CMe)2]: a two-dimensional coordination polymer of the anhydrous manganese acetate polymorphs

Abstract  Two polymorphs of crystalline anhydrous manganese acetate, α-[Mn(O₂CMe)₂] (1) and β-[Mn(O₂CMe)₂] (2), were prepared under temperature-controlled solvothermal dehydration. X-ray single-crystal (and powder) diffractions revealed that compound 1 crystallizes in monoclinic (a = 9.763(4), b = 4.972(2), c = 6.122(3) ?, β = 102.878(5)°, V = 289.7(2) ?³, Z = 4) space group P2/c. Although it was early prepared, its single crystal structure is firstly determined and known as a two-dimensional (2D) layer structure; whereas, compound 2 demonstrates a three-dimensional diamondoid (dia-e) structure that people in its early X-ray single-crystal study was not aware of. Graphical Abstract  Anhydrous α-[Mn(O₂CMe)₂] was discovered in 1967, which two-dimensional layer structure is firstly determined by the X-ray single-crystal analysis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Transition metal complexes with Girard reagent-based ligands. Part IV. Synthesis and characterization of pyridoxilidene Girard-T hydrazone complexes. Crystal structure of the copper(II) complex

Abstract  The monoligand complexes of the formula M(HPLGT)(NCS)₂ (M = Cu(II), Zn(II)) in which the ligand tridentate ONO pyridoxilidene Girard-T hydrazone, [H₃PLGT]Cl₂ · 2H₂O, was coordinated in neutral doubly deprotonated form were synthesized. Also, the first complexes with the ligand coordinated in triply deprotonated monoanionic form of the formula [Cu(PLGT)N₃] and [Co(PLGT)(NO₂)₂NH₃] · 3H₂O are reported. The single crystal X-ray analysis of [Cu(HPLGT)(NCS)₂] showed that Cu(II) is placed in a square-pyramidal surrounding consisting of one tridentate Schiff base and one NCS group in the basal plane and the other NCS group in the apical position. Intermolecular hydrogen bonds leading to centrosymmetrical dimerization of these complexes were discussed. In the reaction of Girard-T and Hacac in the presence of CuCl₂, a mixture of single crystal complexes of the composition [Cu(3,5-Me₂pz)₂Cl₂]₂ and [Cu(acac)₂] · 2[Cu(3,5-Me₂pz)₂Cl₂] was obtained and X-ray analysis of the latter one was reported. Index abstract  Crystal structure of the Cu(II) complex with pyridoxilidene Girard-T hydrazone was analyzed. Additional two Cu(II) complexes obtained by the reaction of Girard-T reagent and Hacac in the presence of CuCl₂ were also studied by single crystal X-ray analysis.      

On the protonation of dibenzo-18-crown-6

Abstract  The stability constant of the dibenzo-18-crown-6·H₃O⁺ cationic complex species dissolved in nitrobenzene saturated with water has been determined from extraction experiments in the two-phase water–nitrobenzene system and from γ-activity measurements. Various structures of protonated dibenzo-18-crown-6 are discussed. Graphical abstract        

Molecular recognition and supramolecular self-assemblies of (±)-2,2′-dihydroxy-1,1′-binaphthyl with aromatic aza compounds

Abstract  (±)-2,2′-dihydroxy-1,1′-binaphthyl (binol) co-crystallized with 1,10-phenanthroline-5,6-dione and acridine to afford co-crystals (Binol)·(1,10-phenanthroline-5,6-dione) 1 and (Binol)·(acridine)₂ 2, respectively. Co-crystal 1 crystallizes in space group P-42(1)c, with a = 14.9921(4), b = 14.9921(4), c = 20.8102(12) ?. Co-crystal 2 crystallizes in space group P2/c, with a = 17.8004(19), b = 10.0093(11), c = 19.393(2) ?, and α = γ = 90°, β = 103.187(2)°. In co-crystal 1, the components form an infinite 1D polar array; whereas in 2, the components form discrete three-component aggregates. Graphical abstract   Molecular recognition and supramolecular self-assemblies of (±)-2,2′-dihydroxy-1,1′-binaphthyl with aromatic aza compounds Baoming Ji, Shaobin Miao, Dongsheng Deng As a result of mutual recognition, (±)-binol with 1,10-phenanthroline-5,6-dione and acridine afforded co-crystals 1 and 2, respectively. In 1 the components form an infinite 1D polar array, whereas in 2 the components form discrete three-component aggregates.      

Ferric nitrate in the presence of catalytic amounts of KBr or NaBr: an efficient and homoselective catalytic media for the selective oxidation of sulfides to sulfoxides

Abstract  A mild, efficient, and highly selective oxidation method of sulfides to sulfoxides using Fe(NO₃)₃·9H₂O and catalytic amounts of KBr or NaBr in the presence of wet SiO₂ (50% w/w) has been developed. A variety of aliphatic and aromatic sulfides were selectively oxidized at room temperature in good to excellent yields. Graphical abstract        

Preparation, molecular structure, and thermal analyses of a novel coordination compound [Cd(AZT)4(H2O)2](PA)2 · 4H2O (AZT = 3-azido-1,2,4-triazole, PA = picrate)

Abstract  The crystal structure of 3-azido-1,2,4-triazole (AZT) has been determined. A novel coordination compound [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been synthesized by using 3-azido-1,2,4-triazole as ligand, and its structure has been characterized by using X-ray single crystal diffraction, elemental analysis, and FT-IR spectroscopy. Each cadmium (II) center is coordinated with four N atoms of four AZT molecules and two O atoms of two H₂O molecules to form a slightly distorted octahedron. The optimized molecular structure and NBO charges of 3-azido-1,2,4-triazole have been obtained from the density functional theory (DFT) with the B3LYP method employing the 6-311 + G** basis sets. Thermal decomposition mechanism of [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been predicted based on DSC, TG-DTG, and FT-IR analyses. The kinetic parameters of the first exothermic process of [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O were studied by applying the Kissinger’s and Ozawa-Doyle’s methods. Index Abstract  A novel coordination compound [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been synthesized by using 3-azido-1,2,4-triazole as ligand and its structure has been characterized by using X-ray single crystal diffraction, elemental analysis, and FT-IR spectroscopy. Each cadmium (II) center is coordinated to form a slightly distorted octahedron. Thermal decomposition mechanism of [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been predicted based on DSC, TG-DTG, and FT-IR analyses.      

[NH4][(CH3)2NH2]2[Ta(C2O4)4]·2H2O: the first (oxalato)tantalate(V) complex structurally characterized

Abstract  The compound [NH₄][(CH₃)₂NH₂]₂[Ta(C₂O₄)₄]·2H₂O has been synthesized and characterized by elemental and TG/DTA analyses, IR spectroscopy and by the single-crystal X-ray diffraction study. The structure comprises the [Ta(C₂O₄)₄]³⁻ anion, NH₄ ⁺ and [(CH₃)₂NH₂]⁺ cations and crystallization water molecules. The Ta atom is octacoordinated by oxygen atoms from four bidentate oxalate groups forming a coordination polyhedron close to the triangular dodecahedron. The charge-assisted hydrogen bonds from both cations connect the [Ta(C₂O₄)₄]³⁻ anions into a three-dimensional framework. Graphical Abstract  The synthesis and properties of [NH₄][(CH₃)₂NH₂]₂[Ta(C₂O₄)₄]·2H₂O, the first structurally characterized compound with the tetra(oxalato)tantalate(V) anion, is reported.      

A combined extraction and DFT study on the complexation of K+ with valinomycin

Abstract  From extraction experiments in the two-phase water–nitrobenzene system and γ-activity measurements, the stability constant of protonated tetraethyl p-tert-butylcalix[4]arene tetraacetate in nitrobenzene saturated with water was determined. By using DFT calculations, the most probable structure of the tetraethyl p-tert-butylcalix[4]arene tetraacetate·H₃O⁺ complex species was derived. Graphical Abstract        

Six coordinate Ni(II) complexes of ONN donor aroylhydrazone ligands: synthesis,spectral studies,and crystal structures

A new ligand N′-(pyridin-2-ylmethylene)nicotinohydrazide (HL²) and two Ni(II) complexes of stoichiometry NiL¹·H₂O [L¹-2-benzoylpyridine nicotinoylhydrazone] and NiL²·H₂O have been synthesized and characterized by elemental analyses, IR and UV–Vis spectral studies. Structures of HL² and Ni(II) compounds have been determined by single crystal X-ray diffraction studies which reveal a distorted octahedral geometry around the two Ni(II) centers.

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Graphical abstract A new ligand N￠-(pyridin-2-ylmethylene)nicotinohydrazide (HL2) and two Ni(II) complexes of stoichiometry NiL1·H2O [L1-2-benzoylpyridine nicotinoylhydrazone] and NiL2·H2O have been synthesized and characterized by elemental analyses, IR, UV–Vis spectral studies and single crystal X-ray analysis.

     

An efficient and convenient protocol for the synthesis of novel 1′H-spiro[isoindoline-1,2′-quinazoline]-3,4′(3′H)-dione derivatives

Abstract  An efficient and direct procedure for the synthesis of novel spiro[isoindoline-1,2′-quinazoline]-3,4′(3′H)-dione derivatives is described. The process employs a condensation reaction of 2-aminobenzamides and isatins in the presence of a catalytic amount of KAl(SO₄)₂.12H₂O (alum) in ethanol under reflux. Graphical Abstract        

The 3D porous metal-organic framework constructed by Cd(II) with 2-methylimidazole-4,5-dicarboxylic acid

Abstract  A 3D metal-organic framework, [C₆H₃CdN₂O₄]·NH₄, was synthesized solvothermally and structurally characterized by single-crystal X-ray structure determination. This compound crystallizes in the tetragonal system with the space group P42/nmc. The crystal structure presents a 3D framework and open channels, exhibiting guest-coordination sites at channel walls and strong fluorescent emission. Graphical abstract        

Coordination polymers with adamantanediacetate bridges: syntheses, structures, and magnetic properties

Abstract  Two new coordination polymers, [CoL(bpp)] _n (1) and [MnL(bipy)] _n ·0.25nH₂L·0.5nH₂O (2) (H₂L = 1,3-adamantanediacetic acid, bpp = 1,3-bis(4-pyridyl)propane, bipy = 4,4′-bipyridine), were synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, and thermal analysis. Complex 1 is an one-dimensional (1D) chain structure of Co(II) bridged by L²⁻ as well as bpp. Complex 2 consists of a two-dimensional (2D) (3,6)-connected topology layer structure. Variable temperature magnetic susceptibility measurements in the range of 2–300 K reveal the existence of weak antiferromagnetic interactions in two complexes with J = −1.74 cm⁻¹, g = 2.26 for 1 and J = −0.10 cm⁻¹, g = 1.67 for 2. Index abstract  Two mental-organic frameworks, namely [CoL(bpp)] _n (1) and [MnL(bipy)] _n ·0.25nH₂L·0.5nH₂O (2) (H₂L = 1,3-adamantanediacetic acid, bpp = 1,3-bis(4-pyridyl)propane, bipy = 4,4′-bipyridine), have been synthesized based on 1,3-adamantanediacetic acid and N-donor coligand with metal ions Co(II) and Mn(II). The magnetic measurement of the two polymers reveals typical antiferromagnetism exchange. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Catalytic oxidation of urazoles and bis-urazoles to their corresponding triazolinediones using aluminium nitrate and a catalytic amount of silica sulfuric acid

Abstract  A simple and efficient catalytic oxidation of urazoles and a bis-urazole to the corresponding triazolinediones by treatment with Al(NO₃)₃.9H₂O in the presence of a catalytic amount of silica sulfuric acid is described. A good range of urazole derivatives was selectively oxidized in CH₂Cl₂ at room temperature in good to excellent yields. Graphical abstract        

Practical and general method for the direct synthesis of alkyl fluorides from alcohols under mild conditions: a reinvestigation

Abstract  In contrast to the results presented in a previous report, the direct conversion of alcohols to alkyl fluorides with triphenylphosphine and potassium fluoride in CCl₄/DMF under mild conditions failed. Graphical Abstract        

Phosphorus heterocycles: synthesis,spectroscopic study and X-ray crystallography of some new diazaphosphorinanes

New diazaphosphorinanes with formula R=C₆H₅O (2), 4-CH₃-C₆H₄NH (3), 4-NO₂-C₆H₄NH (4), R=Cl (5), 4-CH₃-C₆H₄O (6), and C₆H₅NH (7) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR and IR spectroscopy and elemental analysis. The crystal structures of compounds 1 and (8) were determined using X-ray crystallography. In these structures, the P=O bond is placed in an equatorial position and the aliphatic six-membered rings show chair conformations. These compounds form two-dimensional polymeric chains via intermolecular P=O…H–N hydrogen bonds. ¹H NMR spectrum of compound 1 shows a ddd splitting pattern for the coupling of H_equatorial proton with phosphorus atom, H_axial atom, and NH proton with a high-value ³ J(PNCH) coupling constant = 26.1 Hz. But, H_axial indicates a dd splitting pattern because of the coupling with H_equatorial and NH protons. ¹³C NMR spectra of compounds 5–7, indicated high values for ³ J(P,C)_aromatic = 11.9, 11.3 and 10.2 Hz due to the coupling of the aromatic carbon atom of naphthalene moiety with the phosphorus atom. ³¹P NMR spectra indicate that the δ(³¹P) of compounds 1–4 and 8 containing NH groups connected to the aliphatic carbon atoms appear downfield relative to those of compounds 5–7 that containing NH groups connected to the aromatic naphthalene group.

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Graphical abstract

     

Facile synthesis of highly functionalized stable ketenimines by a three-component reaction of alkyl isocyanides, dialkyl acetylenedicarboxylates and ethyl carbazones

Abstract  The reactive intermediate generated by the reaction of alkyl isocyanides and dialkyl acetylenedicarboxylates was trapped by ethyl carbazones to produce stable ketenimine derivatives in good yield. The reaction is characterized by mild conditions, high selectivity, and tolerance to various functional groups. Graphical abstract