Synthesis and characterization of ruthenium (II) carbonyl complexes containing naphthyridine and acetylacetonate ligands and their catalytic activity in the hydrogen transfer reaction

A series of novel complexes of the Ru(L)₂(CO)₂ L = 2-(3′ methoxyphenyl)-1,8-naphthyridine (complex 1), and type Ru(acac)₂(L)(CO) with L = 2-(3′ methoxyphenyl)-1,8-naphthyridine (complex 2), 2-(2′-bromophenyl)-1,8-naphthyridine (complex 3) and 2-phenyl-1,8-naphthyridine (complex 4) was synthesized and characterized. We found that the complexes 2, 3, and 4 can be directly synthesized from Ru₃(CO)₁₂. The complex Ru(acac)₂(L)(CO) L = 2-(3′ methoxyphenyl)-1,8-naphthyridine (2) was characterized by X-ray single crystal analysis which confirms the monodentate coordination mode of the 1,8-naphthyridine derivate and the cis arrangement of the acac ligands. Preliminary studies in transfer hydrogenation of acetophenone in the presence of 2-propanol show the good catalytic activity of complex 2 with 92% conversion.     

Synthesis, structure and catalytic activities for the hydrogen transfer reactions of the ruthenium(II) carbonyl chloride complexes with pyridine-2,6-diimine

Two Ru(II) carbonyl chloride complexes with pyridine-2,6-diimine, (L)Ru(CO)Cl₂ (L = 2,6-diacetylpyridinebis(2,4,6-trimethylanil), 1; L = 2,6-diacetylpyridinebis(2,6-diisopropylanil), 2) have been synthesized and characterized. The structure of compound 1 has been determined by X-ray crystallography, which show the distorted octahedral geometry around Ru(II). Complexes 1 and 2 have been proved to be active in the transfer hydrogenation of acetophenone by propan-2-ol.     

Syntheses, structures and catalytic activities of ruthenium (II) carbonyl iodide complexes with CNC-pincer bis (carbene) ligand

Two new pincer bis (carbene) ligands and corresponding ruthenium (II) carbonyl iodide complexes have been synthesized and characterized. The structures of complexes 3 and 4 have been determined by X-ray crystallography. Complexes 3 and 4 have been proved to be efficient catalysts in the transfer hydrogenation of acetophenone.     

Synthesis,crystal structure and DNA-binding studies of a Ru(II) complex containing two main ligands

A new Ru(II)-polypyridyl complex, [Ru(L)(dppz)₂](PF₆)₄ (L = 5,5′-di(1-(trimethylammonio)methyl)-2,2′-dipyridyl cation; dppz = dipyrido[3,2-a:2′,3′-c]phenazine]), has been synthesized and structurally characterized. The binding of this complex with calf thymus DNA (CT-DNA) has been investigated by spectroscopic and viscosity measurement. Results indicate that the complex binds to CT-DNA via an intercalative mode. Moreover, the complex reveals a highly efficient DNA cleavage activity upon irradiation at 365 nm, during which supercoiled pBR322 DNA was converted to nicked DNA.     

Synthesis and catalytic activity of a novel ruthenium(III) complex containing a sugar-based ligand

The novel mixed-ligand complex [Ru^III(TDL)(bipy)(H₂O)]⁺ (1) (TDL = N-3,5-ditertiarybutylsalicylidine-d-glucosamine; bipy = 2,2′-bipyridine) has been synthesized and characterized. Complex 1 found to catalyze the epoxidation of styrene and oxidize 1-indanol to 1-indanone in dichloromethane using t-BuOOH as a terminal oxidant. Enanantiomeric induction was observed in case of styrene epoxidation. Formation of a high valent Ru(V)-oxo species is proposed to be the catalytic oxidative species.     

Synthesis,structures and catalytic activities of half-sandwich ruthenium complexes based on Schiff Base ligands

A series of half-sandwich ruthenium(II) complexes containing Schiff-base ligands [Ru(p-cymene)LCl] [HL = (E)-4-X-2-((phenylimino)methyl)phenol, X = H (2a); X = CH₃ (2b); X = Cl (2c) and X = Br (2d)] have been synthesized and fully characterized by ¹H and ¹³C NMR spectra, elemental analyses and infrared spectrometry. Moreover, the molecular structures of ruthenium complexes 2b and 2c were confirmed by single-crystal X-ray diffraction methods. These half-sandwich ruthenium complexes are highly catalyzed hydrogenation of nitroarenes to aromatic anilines to proceed in the presence of sodium borohydride reducing agent in ethanol solvent. Notably, complex 2c was found to be a very efficient catalyst toward reduction of nitroarene compounds with wide functional group compatibility and substrate scope.     

A new NiCuCu Ni complex containing doubly end-on azido bridged dicopper(II) and macrocyclic nickel(II) complex ancillary ligands: Synthesis, structure and magnetism

[Cu₂(NiL)₂(N₃)₄] was synthesized by combining “complex as ligand” approach and “pure bridging ligand” approach (H₂L = dimethyl 5,6,7,8,15,16-hexahydro-15-methyl-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate). The two Cu^II ions are bridged by two end-on azido ligands. ππ and oxamido–carbonyl interactions link the molecules into 1D supramolecular chains. Ferromagnetic interactions exist between the two Cu^II ions.     

Synthesis, characterization and crystal structure of a novel thiocyanate–ruthenium(II) complex

The cis-[Ru(dppb)(Me-bipy)(NCS)₂], dppb = 1,4-bis (diphenylphosphino)butane, Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, and NCS = thiocyanate, was synthesized and characterized by spectroscopic and electrochemical techniques and its structure was determined by crystal X-ray analysis. The crystal structure reveals that the coordination geometry around the Ru(II) center is distorted octahedron where two molecules of thiocyanate are bonded to the ruthenium through nitrogen atom in cis orientation. The half-wave formal potential value E_1/2 = 0.8 V (versus Ag/AgCl) observed is considerable higher than that for the cis-[RuCl₂(dppb)(Me-bipy)] complex, E_1/2 = 0.6 V (versus Ag/AgCl), well illustrating the strong π-acceptor effect the NCS ligand toward the backbonding interaction with the Ru(II) metal center. The MLCT absorption bands of the thiocyanate complex present a higher molar absorptivity (about 12%) compared with the cis-[RuCl₂(dppb)(Me-bipy)] complex, in the same experimental conditions. These properties make the complex potentially promising for the photosensitization process.     

Synthesis,characterization and catalytic activities of ruthenium complexes containing triphenylphosphine/triphenylarsine and tetradentate Schiff bases

Ruthenium(II) complexes of the type [Ru(CO)(B)(L)] (B=AsPh₃, pyridine, piperidine or morpholine; L=dianion of tetradentate Schiff bases) have been synthesized and characterized by physico-chemical methods. These complexes are found to be effective catalysts in the oxidation of primary and secondary alcohols using N-methylmorpholine-N-oxide as oxidant. The catalytic activity of these triphenylarsine complexes have been compared with that of triphenylphosphine complexes and with similar ruthenium(III) complexes. The formation of high valent Ruⁿ⁺²O species as catalytic intermediate is proposed for the catalytic processes.     

Synthesis,characterization, and catalytic behavior of mono- and bimetallic ruthenium(II) and iridium(III) complexes supported by pyridine-functionalized N-heterocyclic carbene ligands

We have prepared and characterized five unreported ruthenium(II) and iridium(III) complexes supported by pyridine-functionalized N-heterocyclic carbene ligands including a bimetallic iridium(III) complex. When activated, all complexes are active catalysts for the transfer hydrogenation of acetophenone.     

Arene ruthenium(II) p-chloroacetophenone phenylthiosemicarbazone complex mediated transfer hydrogenation of ketones

A series of cationic half-sandwich arene ruthenium(II) complexes of general formula [Ru(η⁶-p-cymene)Cl(L)]Cl have been synthesized from the reaction of [Ru(η⁶-p-cymene)Cl₂]₂ with thiosemicarbazone derivatives (L). Characterization of the complexes were accomplished by analytical and spectral (FT-IR, UV–Vis, ¹H NMR) methods. Single crystal structure determination reveals the presence of a pseudooctahedral three-legged piano stool conformation. All the complexes exhibit a quasi-reversible one electron reduction in the range from ?0.75 to ?0.85 V. Further, the catalytic activity of the titled complex has been investigated in the transfer hydrogenation of ketones in the presence of isopropanol/NaOH.     

Synthesis,crystal structure of copper(II) complexes comprising 2-(biphenylazo)phenol and 1-(biphenylazo)naphthol ligands and their catalytic activity in nitroaldol reaction

New series of copper(II) complexes of the type [Cu(L)₂] (L = L₁–L₅) comprising bidentate 2-(biphenylazo)phenol (HL₁–HL₄) and 1-(biphenylazo)naphthol (HL₅) ligands have been synthesized. The composition of complexes and ligands (HL₁–HL₄) has been established by elemental analysis and spectral (FT–IR, UV–Vis, ¹H NMR and EPR) methods. Molecular structures of copper complexes [Cu(L₃)₂] (3) and [Cu(L₅)₂] (5) were established by X-ray crystallography. These Copper(II) biphenylazo complexes exhibit a very good catalytic activity towards nitroaldol reaction of various aldehydes with nitromethane.     

Synthesis,crystal structure of two new Zn(II), Cu(II) porphyrins and their catalytic activities to ethylbenzene oxidation

One novel porphyrin 5,10,15,20-tetra(4-(4-acetateethyl)phenoxy)phenylporphyrin (H₂Pp), and its two corresponding zinc(II) and copper(II) porphyrins (ZnPp, CuPp) is synthesized and characterized by spectroscopic techniques. The single crystal structures of [ZnPp(DMF)]·DMF (1) and [CuPp(DMF)] (2) are also obtained and analyzed. Complex 1 crystallizes in monoclinic system compared to the triclinic system of complex 2, which may due to the influence of solvent DMF molecule in 1. The metal centers have similar coordination environments in the two structures, which are all five-coordinated pyramid geometry with four nitrogen atoms of porphyrin ring from equator and an axial oxygen atom of DMF molecule. 1 and 2 display 3D supramolecular structures constructed by π⋯π interactions of porphyrin rings and C–H⋯O hydrogen bonds. The catalytic activities of 1 and 2 to the ethylbenzene oxidation are examined. The results indicate that both of them exhibit highly selectivity to acetophenone (> 99%) with the conversion of 23% (1) and 76% (2) respectively.     

Ruthenium catalyzed asymmetric transfer hydrogenation based on chiral P,N,O Schiff base ligands and crystal structure of a ruthenium(II) complex bearing chiral P,N,O Schiff base ligands

A ruthenium catalyst, generated in situ by heating the chiral P,N,O Schiff base ligand L (L = (S)-Ph₂PC₆H₄CNCHPhCH₂OH) with Ru(DMSO)₄Cl₂ in 2-propanol, is active for asymmetric transfer hydrogenation with best enantioselectivity up to 81%. A ruthenium complex of formula RuL₂Cl₂ is prepared and its crystal structure revealed that the two chiral P,N,O Schiff ligands are in meridional configuration. This complex is also an active catalyst for asymmetric transfer hydrogenation. However, the ‘[Ru(DMSO)₄]Cl₂ + chiral P,N,O ligand’ protocol displays better enantioselectivity.     

Synthesis, structure and magnetic properties of a novel lead(II) complex containing nitronyl nitroxide radicals

The lead(II) complex with nitronyl nitroxide, [Pb(NIT2Py)₂(NO₃)₂] [NIT2Py = 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], has been prepared and characterized by magnetic and single-crystal X-ray diffraction studies. In the complex, the lead(II) ion is coordinated with two bidentate nitronyl nitroxide and two nitrate anions. The lead(II) ion shows seven-coordinate geometry. Magnetic susceptibility data for the title complex has been measured in the range 5–300 K. There are antiferromagnetic interaction between the coordinated nitronyl nitroxides (J = −19.35 cm⁻¹) and intermolecular ferromagnetic interactions. Thus, we observe the sixth periodic IVA group metal element Pb(II) ion providing an effective pathway for the magnetic exchange interaction between nitronyl nitroxide radicals.     

A novel cobalt(II) acylpyrazolonate complex with intermolecular hydrogen bond: Synthesis,structure and properties

A new cobalt complex, [Co(L)₂·(H₂O)₂](HL = 4-hexanoyl-3-methyl-1-phenyl-1H -pyrazol-5(4H)-one), was synthesized by us. The complex was characterized by single crystal X-ray diffraction, IR, UV, fluorescence spectra and thermogravimetric analysis. The results of characterization showed that the crystal is monoclinic system with crystal parameters: a = 15.2439(12) Å, b = 7.4101(6) Å, c = 15.7381(18) Å, and Z = 2, S = 1.074. It was found that the Co²⁺ is located in the inversion center of the complex. The Co(II) had an ideal octahedral coordination environment with four oxygen atoms of HL ligands in the equatorial plane and two water molecules in axial positions. The complex exhibits yellow emission as the result of the fluorescence from the intraligand emission excited state.     

Synthesis,characterization and catalytic activity of Fe(III) complexes containing Schiff base and triphenylphosphine ligands

The oxidation of alcohols to carbonyls was investigated by an efficient catalyst system comprising of Fe(III)–Schiff base–triphenylphosphine complex. The complex chloroN-(2-mercaptophenyl)salicylideneiminebis(triphenylphosphine)iron(III) showed higher activity for oxidation of various alcohols under relatively mild conditions.     

Synthesis,crystal structure and magnetic characterization of a dinuclear Mn(II) complex with double end-on azide ligands

A new dinuclear manganese(II) complex [MnL(N₃)₂]₂ · 2CH₃OH 1 has been synthesized and characterized crystallographically and magnetically. L is a tridentate Schiff base ligand which is derived from the reaction of pyridine-2-carbaldehyde and 2-aminoethylbenzimidazole. In the complex 1, each Mn(II) ion is coordinated by one L, one terminal azide ligand and symmetrical double end-on bridging azide ligands. The intermolecular hydrogen bonds extend the structure into a two-dimensional layer. Magnetic determination of 1 indicates that ferromagnetic exchange interaction between the two manganese(II) ions exist in this complex through the double end-on azide bridges.     

One-dimensional copper(II) complex containing alternate single and double end-on azide ligands: Crystal structure and magnetic characterization

A novel one-dimensional azido-bridged coordination polymer of formula [Cu₂(L)₂(H₂O)(N₃)₄]_n (1) has been synthesized and characterized crystallographically and magnetically, where L is 5-methylpyrimidin-2-amine. Complex 1 consists of 1D chain in which the Cu(II) ions with a square pyramidal geometry are alternately bridged by asymmetric single and symmetric double end-on (EO) azido ligands. Magnetic analysis reveals that the dominating ferromagnetic interaction is mediated by the symmetric double azido bridge with the exchange parameter J = 55.17 cm⁻¹.