Photooxidation of N,N-bis(3,5-di-tert.-butylsalicylidene)-1,2-diamino hexane-manganese(III) chloride (Jacobsen catalyst) in chloroform

Mn^III(J-salen)Cl (Jacobsen catalyst) with J-salen=N,N^′-bis(3,5-di-tert.-butylsalicylidene)-1,2-diaminocyclohexane dianion in CHCl₃ is photooxidized by the solvent to a Mn^IV(J-salen) complex, presumably Mn^IV(J-salen)Cl₂, with φ=0.002 at λ_irr=333 nm.     

Formation of first gold(III) complex of an N(4)-disubstituted thiosemicarbazone derived from 2-benzoylpyridine: structural and spectral studies

The reaction between gold(III) chloride(AuCl₃) and 2-benzoylpyridine N(4), N(4)-(butane-1,4-diyl) thiosemicarbazone (HBpypTsc) leads to an unexpected formation of a first gold(III) complex from an N(4)-disubstituted thiosemicarbazone derived from 2-benzoylpyridine. The crystal structure, spectroscopic characterization, and preliminary biological activity of [Au(III)(Cl)(BpypTsc)][Au(I)Cl₂] complex are discussed herein.     

LiFePO4 cathode in N-methyl-N-propylpiperidinium and N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide

Ternary [Li⁺][MePrPip⁺][NTf₂⁻] and [Li⁺][MePrPyrr⁺][NTf₂⁻] room temperature ionic liquids (ILs) were obtained by dissolution of solid lithium bis(trifluoromethanesulfonyl)imide (LiNTf₂) in liquid N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide and N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, respectively, and studied as electrolytes for the use in Li/LiFePO₄ or C(Li)/LiFePO₄ batteries. The cell worked properly in the presence of 10 wt% of vinylene carbonate (VC). Impedance-spectroscopy studies showed that the additive (VC) forms a protective coating on the anode. The LiFePO₄ cathode shows good efficiency (135 mAh g⁻¹) working together with [Li⁺][MePrPip⁺][NTf₂⁻] + VC and [Li⁺][MePrPyrr⁺][NTf₂⁻] + VC ionic liquid electrolytes. The flash point of ionic liquid electrolytes containing 10 wt% of VC is above 300 °C, which makes them practically non-flammable.     

Bis(imido) rhenium complexes bearing C- or N-capped ‘tripodal’ ligands: Bi- versus tri-dentate ligation

The differing geometrical constraints of the tripodal ligands tris(hydroxyphenyl)amine (N-cappedH₃) and tris(3,5-di-t-Bu-2-hydroxyphenyl)methane (C-cappedH₃) led, on reaction with [Re(t-BuN)₃(OSiMe₃)], to the isolation of the complexes [Re(t-BuN)₂(N-capped)] (1) and [Re(OSiMe₃)(t-BuN)₂(C-cappedH)] (2), respectively. Both 1 · 1/2MeCN and 2 have been structurally characterized using X-ray synchrotron radiation.     

Preparation, crystal structure and properties of two novel metal-organic frameworks assembled from pyridine-3,5-dicarboxylic acid N-oxide

Two novel coordination polymers, [Cu(PDCO) · (H₂O)]_n (1) and [Cd(PDCO)(bipy) · (H₂O) · 5H₂O]_n (2), (H₂PDCO = pyridine-3,5-dicarboxylic acid N-oxide, bipy = 4,4′-bipyridine), have been synthesized under hydrothermal conditions, and their structures were determined by single-crystal X-ray diffraction studies. Polymer 1 features a three-dimensional (3D) network with nonequivalent nodes of (6³)₂(6⁹ · 8⁵ · 10) topology. Polymer 2 exhibits one-dimensional (1D) double-stranded chains. The magnetic character of 1 as well as the gas adsorption and luminescent properties of 2 have been investigated.     

Molecular structures and vibrational frequencies for cis-[PdCl2(tmen)] and cis-[Pd(N3)2(tmen)]: A DFT study

Theoretical molecular structures of the complexes cis-[PdCl₂(tmen)] and cis-[Pd(N₃)₂(tmen)] (tmen = N,N,N′,N′-tetramethylethylenediamine) were investigated using B3LYP/DFT method. The calculated molecular parameters, bond distances and angles, revealed a square-planar geometry around the metallic center for both compounds with the azide being linear. The theoretical infrared spectra of C₁ symmetry (electronic state ¹A) of the compounds are in agreement with the experimental data.     

Cobalt(II), Zinc(II) and Cadmium(II)-Squarate Complexes with N-Methylimidazole

Three M(II)-squarate complexes, [Co(sq)(H₂O)(Nmim)₄] (1), [Zn(μ_1,3-sq)(H₂O)₂ (Nmim)₂] _n (2) and [Cd(μ_1,3-sq)(H₂O)₂(Nmim)₂] _n (3) (sq = squarate, Nmim = N-methylimidazole) have been synthesized and characterized by elemental, spectral (IR and UV–Vis.) and thermal analyses. The molecular structures of the complexes have been investigated by single crystal X-ray diffraction technique. The squarate ligand acts as two different coordination modes as a monodentate (in 1) and bis(monodentate) (O ^1– O ³ ) bridging ligand (in 2, 3). The Co(II) atom has a distorted octahedral geometry with the basal plane comprised of three nitrogen atoms of Nmim ligands and a oxygen atom of squarate ligand. The axial position is occupied by a nitrogen atom of Nmim and one aqua ligand. The crystallographic analysis reveals that the crystal structures of 2 and 3 are one-dimensional linear chain polymers along the c and b axis, respectively. The configuration around each metal(II) ions are distorted octahedral geometry with two nitrogen atoms of trans-Nmim, two aqua ligands and two oxygen atoms of squarate-O¹,O³ ligand. These chains are held together by the C–H···π, π···π and hydrogen-bonding interactions, forming three-dimensional network.     

The first P–N containing RuCl3NO complex: fac-[RuCl3(NO)(P–N)] (P–N = [o-(N,N-dimethylamino)phenyl]diphenylphosphine)

Complex fac-[RuCl₃(NO)(P–N)] was synthesized from [RuCl₃(H₂O)₂(NO)] in methanol solution under reflux. The orange solid obtained was characterized by NMR (³¹P{¹H}, ¹H, ¹³C) and, cyclic voltammetry, ESI-MS, IR, elemental analysis and X-ray diffraction structure determination. The ³¹P{¹H} reveals the presence of singlet at 36 ppm. IR N–O stretching as KBr pellets or CH₂Cl₂ solution presented 1866 cm⁻¹ and 1872 cm⁻¹, respectively.     

Self-assembly of organometallic Pd(II) complexes via CH3π interactions: The first example of a cyclopalladated compound with herringbone stacking pattern

Two binuclear cyclometallated compounds [Pd(C²,N-dmba)(μ-N₃)]₂ (1) and [Pd₂(C²,N-dmba)₂(μ-N₃)(μ-Cl)] (2) (dmba = N,N-dimethylbenzylamine) have been synthesized and characterized by elemental analysis, IR and NMR spectroscopies and single crystal X-ray diffraction crystallography. The ability of CH₃ groups to form C(sp³)Hπ hydrogen bonds with phenyl rings is responsible for the molecular self-assembly within the crystals of 1 and 2. Compound 1 crystallizes as one-dimensional supramolecular chains whereas the crystal packing of 2 consists of a herringbone of sandwiches composed by two inversely related [Pd₂(C²,N-dmba)₂(μ-N₃)(μ-Cl)] molecules.     

Solvothermal in situ formation of a hexanuclear copper(I) complex with 2-thiolate-N,N′-dimethylnicotinamide

Solvothermal reaction of 2-mercaptonicotinic acid (HL¹) with copper(II) nitrate in DMF/methanol medium leads to the production of a novel hexanuclear complex [Cu(L²)]₆ · (H₂O)₂ (1), in which in situ formation of an anionic ligand 2-thiolate-N,N′-dimethylnicotinamide (L²) and reduction of copper(II) to copper(I) are observed. X-ray single-crystal structure of 1 reveals that each copper(I) center adopts a trigonal geometry provided by two thiolate and one pyridyl groups from three separated L² ligands. As a result, six copper(I) ions are interconnected by six μ₃–L² bridges to afford a hexanuclear cluster, in which the octahedral Cu₆ core is stabilized by significant cuprophilic interactions.     

Synthesis of Silica-Supported Platinum(II) and Nickel(II) Complexes of Bis(Diphenylphosphinomethyl)Amino Ligand: Applications as Catalysts for the Synthesis of 2-Methyl-1,4-Naphthoquinone (Vitamin K3)

Pt(II) and Ni(II) complexes of N,N-bis(diphenylphosphinomethyl)aminopropyltriethoxysilane [(CH₃CH₂O)₃Si(CH₂)₃N(CH₂PPh₂)₂] (DIPAPTES) and silica supported [SiO₂–(DIPAPES)] ligands have been synthesized under nitrogen atmosphere using Schlenk method and characterized by using atomic absorption, FT-IR, NMR (¹H and ³¹P) and elemental analysis techniques. All the complexes were used as catalysts for the oxidation of 2-methyl naphthalene (2MN) to 2-methyl-1,4-naphthoquinone (vitamin K₃, menadione, 2MNQ) using hydrogen peroxide as a clean and cheap oxidant. [Pt–(DIPAPTES)Cl₂] and supported complex [SiO₂–(DIPAPES)–PtCl₂] showed medium catalytic activity whereas Ni(II) complexes did not show any catalytic activity for the selective oxidation of 2-methyl naphthalene to 2-methyl-1,4-naphthoquinone.     

Synthesis,spectral and antibacterial studies on Ni(II) and Zn(II) complexes involving N-furfuryl-N-isopropyldithiocarbamate (f iprdtc) and Lewis bases: X-ray structure of [Ni(f iprdtc)(NCS)(PPh3)]

[Ni(fⁱprdtc)₂] (1), [Ni(fⁱprdtc)(PPh₃)(NCS)] (2), [Ni(fⁱprdtc)(PPh₃)₂]ClO₄ (3), [Zn(fⁱprdtc)₂] (4), [Zn(fⁱprdtc)₂(1,10-phen)] (5) and [Zn(fⁱprdtc)₂(2,2′-bipy)] (6) (f ⁱprdtc=N-furfuryl-N-isopropyldithio- carbamate, 1,10-phen=1,10-phenanthroline and 2,2′-bipy=2,2′-bipyridine) complexes were prepared and characterized by elemental analysis, electronic, IR and NMR spectra and the structure of 2 was determined by single-crystal X-ray crystallography. UV–Vis spectral data of 1–3 are consistent with the formation of square planar complexes. IR spectra of the complexes show the contribution of the thioureide form to the structure. A single-crystal X-ray structural analysis of 2 proved four-coordinated nickel in a distorted square planar arrangement with a S₂PN donor set. Significant asymmetry in Ni–S bond distances was observed in [Ni? S1=2.1655(8); Ni? S2=2.2120(8) Å]. This observation clearly supports the less effective trans of SCN^? over PPh₃. The observed shielding in N¹³CS₂ chemical shifts of heteroleptic nickel complexes 2 and 3 when compared with homoleptic nickel complex 1 indicates the effect of PPh₃ on the mesomeric drift of electron density toward nickel through the thioureide C? N bond. The N¹³CS₂ chemical shift of 5 and 6 are additionally deshielded compared with 4 owing to the increase in coordination number. Complexes were screened for in vitro antibacterial activity and significant activity has been found.     

Synthesis, structure and photoluminescence of a novel palladium(I) compound: [Pd3(μ3-Cl)2(dppp)3][Pd2(μ2-Cl)3(PPh3)2](PPh3)2

Pd(PPh₃)₂Cl₂ reacts with PdCl₂ and 1,3-bis(diphenylphosphine)propane (dppp) in ethanol–DMF–pyridine mixed solvent to yield a novel palladium(I) compound [Pd₃(μ₃-Cl)₂(dppp)₃][Pd₂(μ₂-Cl)₃(PPh₃)₂](PPh₃)₂. It features an isolated structure based on [Pd₃(μ₃-Cl)₂(dppp)₃]⁺ cations having triangulo-palladium clusters and [Pd₂(μ₂-Cl)₃(PPh₃)₂]⁻ anions in which the coordination environment of palladium is an unusual tetrahedral geometry. Its photoluminescence is measured.     

Synthesis of polymers and copolymers of c-(N-AcrLys-Sar) and their interaction with small molecules in solution

An acrylamide derivative having a mono-N-methylated cyclic dipeptide as a substituent, c-(N^εAcrLys-Sar), was synthesized and polymerized by radical polymerization, giving homopolymers and copolymers with styrene, 4-vinylpyridine, and N-dodecylacrylamide. The relative reactivities of these monomers in the radical polymerization decreased in the following order: styrene > 4-vinylpyridine > N-dodecylacrylamidec-(N^ε-AcrLys-Sar). Poly[c-(N^ε-AcrLys-Sar)] was soluble in water and the usual organic solvents except diethylether and n-hexane. In mixed solvent, poly[c-(N^ε-AcrLys-Sar)] interacted most strongly with Ba²⁺ among alkali and alkaline-earth metal cations. A cyclic dipeptide, which is equivalent to the side chain of poly[c-(N^ε-AcrLys-Sar)], did not interact with these cations, indicating that the side chain ligand groups of poly[c-(N^ε-AcrLys-Sar)] interacts specifically with Ba²⁺ by intramolecular cooperation. However, the copolymer of c-(N^ε-AcrLys-Sar) with styrene interacts more strongly with larger alkali cations, and equally well with Ba²⁺ and Ca²⁺. These results indicate that the styrene units in the copolymer influence its solubility and regulate the intramolecular cooperation of the cyclic dipeptide ligand groups as spacer groups. The copolymer of c-(N^ε-AcrLys-Sar) with 4-vinylpyridine interacted very strongly with Ba²⁺ as a result of the intramolecular cooperation of a pyridyl group and a cyclic dipeptide group. The formation constant of the ternary complex was determined to be 10⁹ M⁻³, which is larger by 10² fold than that by a polymer carrying benzo-15-crown-5 in the side chain. The copolymer of c-(N^ε-AcrLys-Sar) with N-dodecylacrylamide was found to bind methyl orange in aqueous solution by hydrophobic interaction. The copolymer of c-(N^ε-AcrLys-Sar) with styrene was found to extract phenylalanine from an aqueous solution to a n-octanol phase. However, the extraction was not enantiomer-selective.     

Syntheses and topological networks of two azide complexes based on 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligands

Two new azide complexes, [Cd₂(3-abpt)(N₃)₄]_n (1) and [Cu(3-abpt)₂(N₃)₂] (2) (3-abpt = 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole), have been prepared and structurally characterized. Complex 1 displays an interesting 2D polymeric structure with rarely reported 3,7-connected (3²;4)(3⁴;4⁶;5⁶;6⁵) network in the Schafli notation. Complex 2 contains mononuclear pieces, and they are linked each other through weak CuN coordination bonds to form a 2D sheet with (4, 4) topology. The thermal stability and fluorescent property of 1 have also been investigated.     

New (κ-C,N)-palladacyclic complexes with benzimidazol-2-ylidene ligand: Synthesis, crystal structures and characterization

Reaction of unsymmetrical benzimidazolium bromides (1) with Ag₂O and subsequent transmetallation with chloro-bridged dinuclear palladacycle, [Pd(dmba)(μ-Cl)]₂ (dmba: N,N-dimethylbenzylamine) afforded benzannulated monocarbene complexes [Pd(dmba)(NHC)Cl], 2. The palladacycles (2a–c) were characterized by elemental analysis; NMR spectroscopy and the molecular structure of 2a and 2c were determined by X-ray crystallography.     

Solvent-induced assembly of two supramolecular isomers of Mn thiophenedicarboxylate coordination polymers

Two supramolecular isomers of Mn^II thiophenedicarboxylate coordination polymers, namely, [Mn₂(tdc)₂(dmf)₂]_n (1) and [Mn₃(tdc)₃(dmf)₃]_n (2) (H₂tdc = 2,5-thiophenedicarboxylic acid, dmf = N,N-dimethylformamide), were synthesized with solvent-induced assembly method and the antiferromagnetic interactions between the Mn^II ions in their solid phase were measured.     

Novel Hg and Mn supramolecular complexes with a versatile building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiolate involving in situ ligand formation

Reaction of potassium N′-(pyridine-4-carbonyl)-hydrazinecarbodithioate ([K⁺(H₂L)⁻]) with Hg^II or Mn^II inorganic salt in the presence of 1,10-phenanthroline (phen) or 4,4′-bipyridine (bipy), yields complexes [Hg(pyt)₂(phen)] (1) and {[Mn(pyt)₂(H₂O)₂]·(bipy)·(H₂O)₂}_n (2), in which the pyt ligand (Hpyt = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol) is obtained by in situ ligand formation from the acyclic precursor [K⁺(H₂L)⁻]. Single crystal X-ray diffraction suggests that the pyt anionic ligands in 1 and 2 behave as thiolate and thione isomers, respectively, and display S- and μ-N_pyridyl, N_oxadiazole-binding fashions. Complex 1 shows a 1-D fishbone-like supramolecular array via strong aromatic stacking interactions between the discrete mononuclear coordination motifs, whereas 2 has a 2-D layered host coordination framework with the inclusion of bipy and water guests in the cavities.     

A microporous [Ni3(μ3-OH)] cluster-based framework with 9-connected ncb topology

A porous metal organic framework [Ni^IIINi^II₂(μ₃-OH)(bdc)_1.5(int)₃]_n x(solvents) (1: bdc = 1,4-benzenedicarboxylate; int = isonicotinate) based on the trinuclear Ni₃(μ₃-OH) units was solvothermally synthesized and structurally characterized. It features a three-dimensional 9-connected ncb-type framework with two kinds of cage substructures and large one-dimensional channels. Both N₂ and CO₂ gas sorption studies of 1 were investigated to demonstrate the permanent porosity in 1.     

Single‐Pot Ethane Carboxylation Catalyzed by New Oxorhenium(V) Complexes with N,O Ligands

The oxorhenium(V) chelates [ReOCl(N,O‐L)(PPh₃)] [N,O‐L=(OCH₂CH₂)N(CH₂CH₂OH)(CH₂COO) ( 2 ), (OCH₂CH₂)N(CH₂COO)(CH₂COOCH₃) ( 3 )] and [ReOCl₂(N,O‐L)(PPh₃)] [N,O‐L=C₅H₄N(COO‐2) ( 4 ) C₅H₃N(COOCH₃‐2)(COO‐6) ( 5 )] have been prepared by reaction of [ReOCl₃(PPh₃)₂] ( 1 ), in refluxing methanol, with N,N‐bis(2‐hydroxyethyl)glycine [bicine; N(CH₂CH₂OH)₂(CH₂COOH)], N‐(2‐hydroxyethyl)iminodiacetic acid [N(CH₂CH₂OH)(CH₂COOH)₂], picolinic acid [NC₅H₄(COOH‐2)] or 2,6‐pyridinedicarboxylic acid [NC₅H₃(COOH‐2,6)₂], respectively, with ligand esterification in the cases of 3 and 5 . All these complexes have been characterized by IR and multinuclear NMR spectroscopy, FAB⁺‐MS, elemental and X‐ray diffraction structural analyses. They act as catalysts, in a single‐pot process, for the carboxylation of ethane by CO, in the presence of potassium peroxodisulfate K₂S₂O₈, in trifluoroacetic acid (TFA), to give propionic and acetic acids, in a remarkable yield (up to ca. 30%) and under relatively mild conditions, with some advantages over the industrial processes. The picolinate complex 4 provides the most active catalyst and the carboxylation also occurs, although much less efficiently, by the TFA solvent in the absence of CO. The selectivity can be controlled by the ethane and CO pressures, propionic acid being the dominant product for pressures about ca. 7 and 4 atm, respectively (catalyst 4 ), whereas lower pressures lead mainly to acetic acid in lower yields. These reactions constitute an unprecedented use of Re complexes as catalysts in alkane functionalization.