Syntheses Characterization of Chloro-cyclopentadienyltricarbonyl-molybdenum with β-Cyclodextrin Supramolecular

Organotransition metal complex have been extensively used as homogeneous catalysts in organic reactions and much effort has been paid to improve their activity and selectively. Cyclodextrins have been studied as a model of enzyme for selective catalysis. However, so far there are only a few reports on the inclusion compounds of organometallic complexes with cyclodextrins. Breslow et al.repored high acylation rates for β-CD using ferrocene derivatives and assumed β-CD substrate complexes as intermediate [1]..larad et al reported the preparation and propertics of cyclodextrin-ferrocen inclusion compounds as the first example of cyclodextrin inclusion compounds of organotransition metal complexes[2]. Song Le-Xin et al reported the supramolecular inclusion compound of β-cyclodextrin with cyclopentadieny-tricarbonylmanganese [3] .To our knowledge, there are no reports of inclusion compounds of β-CD with molybdenum organometallic complexes. In the present work we described the preparation and properties of the supramolecular of CpMo(CO)3Cl with β-CD in details.     

手性金属配合物催化的前手性羰基化合物的不对称硅 氢化反应研究进展

评述了近年来手性金属配合物催化的前手性羰基化合物的不对称硅氢化反应研究进展。     

均相salen类配合物催化不对称氰化反应研究进展

手性α-氰醇类化合物在有机合成领域中的应用非常广泛,分子中α-碳原子上连接的羟基和氰基两个官能团很容易控制、转化为大量极其重要的合成中间体,包括：α-羟基酸、α-羟基酯,α-羟基醛、α-羟基酮、α-胺基酸和β-胺基醇等.这些化合物都是工业上合成医药、农化产品、     

手性金属配合物催化的前手性羰基化合物的不对称硅氢化反应研究进展

评述了近年来手性金属配合物催化的前手性羰基化合物的不对称硅氢化反应研究进展。     

1,2-Thio group migration in Rh(II) carbene reactions

[reaction: see text] A series of beta-thio group substituted alpha-diazo carbonyl compounds have been prepared by nucleophilic substitution reactions of thiophenol, thionaphthol, or benzyl mercaptan with beta-acetoxy-alpha-diazo carbonyl compounds. The diazo decomposition of these diazo carbonyl compounds with various transition metal catalysts, including Rh(II) carboxylates and Cu(I) and Cu(II) complexes, has been investigated. It was found that the diazo decomposition of these compounds gave 1,2-thio group migration products. No 1,2-hydride or 1,2-aryl migration products were observed in all cases.     

Half‐sandwich ruthenium‐based versatile catalyst for both alcohol oxidation and catalytic hydrogenation of carbonyl compounds in aqueous media

A series of half‐sandwich ruthenium‐based catalysts for both alcohol oxidation and carbonyl compounds hydrogenation have been synthesized through metal‐induced C–H bond activation based on benzothiazole ligands. The neutral ruthenium complexes 1 – 4 were fully characterized by UV–vis, NMR, IR, and elemental analysis. Molecular structures of complexes 1 and 3 were further confirmed by X‐ray diffraction analysis. All complexes exhibited high activity for the catalytic oxidation of a variety of alcohols with ^tBuOOH as oxidants to give carbonyl compounds with high yields in water. Moreover, these half‐sandwich complexes also showed high efficiency for the catalytic hydrogenation of carbonyl compounds in a methanol–water mixture. The catalyst could be reused for at least five cycles without any loss of activity. The catalytic system also worked well for various kinds of substrates with either electron‐donating or electron‐withdrawing groups.     

New Sulfur and Phosphorus Containing Metal Complexes on the Basis of Trithiophosphites. Synthesis and Properties

Abstract

New sulfur- and phosphorus containing metal complexes have been obtained by means of reactions of trialkyl- and triaryltrithiophosphites with transition metal halides. Their reactions with proton containing and carbonyl compounds have been studied.     

Change in spin state and enhancement of redox reactivity of photoexcited states of aromatic carbonyl compounds by complexation with metal ion salts acting as Lewis acids. Lewis acid-catalyzed photoaddition of benzyltrimethylsilane and tetramethyltin via photoinduced electron transfer

The lowest excited state of aromatic carbonyl compounds (naphthaldehydes, acetonaphthones, and 10-methylacridone) is changed from the n,pi triplet to the pi,pi singlet which becomes lower in energy than the n,pi triplet by the complexation with metal ions such as Mg(ClO(4))(2) and Sc(OTf)(3) (OTf = triflate), which act as Lewis acids. Remarkable positive shifts of the one-electron reduction potentials of the singlet excited states of the Lewis acid-carbonyl complexes (e.g., 1.3 V for the 1-naphthaldehyde-Sc(OTf)(3) complex) as compared to those of the triplet excited states of uncomplexed carbonyl compounds result in a significant increase in the redox reactivity of the Lewis acid complexes vs uncomplexed carbonyl compounds in the photoinduced electron-transfer reactions. Such enhancement of the redox reactivity of the Lewis acid complexes leads to the efficient C-C bond formation between benzyltrimethylsilane and aromatic carbonyl compounds via the Lewis-acid-promoted photoinduced electron transfer. The quantum yield determinations, the fluorescence quenching, and direct detection of the reaction intermediates by means of laser flash photolysis experiments indicate that the Lewis acid-catalyzed photoaddition reactions proceed via photoinduced electron transfer from benzyltrimethylsilane to the singlet excited states of Lewis acid-carbonyl complexes.     

Preparation and Properties of Inclusion Compounds of Cyclodextrins with Organotransition Metal Complexes

Inclusion compounds of transition metal complexes of cycloocta-1,5-diene (cod) and norbornadiene (nbd) with cyclodextrins were prepared. Two-to-one (cyclodextrin:guest) inclusion compounds were obtained in high yields by the treatment of β-cyclodextrin (β-CD) with [(L)RhCl]₂ (L = nbd or cod) and 1:1 inclusion compounds were obtained by the reaction of β-CD with (cod)PtX₂ (X = Cl, Br, or I) in high yields, while γ-CD formed 1:1 inclusion compounds with (cod)PtX₂ (X = Br or I). The formation of inclusion compounds is selective. α-CD did not form inclusion compounds with any transition-metal complexes with cycloocta-1,5-diene. Thermogravimetric measurements show that the complexes are stabilized by inclusion in cyclodextrin cavities. The inclusion compounds were characterized by ¹ H-NMR, IR, UV, and circular dichroism spectra.     

One‐Pot Mechanosynthesis with Three Levels of Molecular Self‐Assembly: Coordination Bonds,Hydrogen Bonds and Host–Guest Inclusion

Liquid‐assisted grinding (LAG) was used to combine three levels of molecular self‐assembly into a one‐pot mechanochemical approach for the construction of metal–organic materials. The approach was applied for the construction of three adducts of cobalt(II) dibenzoylmethanate with isonicotinamide, nicotinamide and imidazole, to screen for their inclusion compounds. The one‐pot process consists of: i) The coordination‐driven binding of addends to the equatorially‐protected metal ion, resulting in “wheel‐and‐axle”‐shaped complexes; ii) self‐assembly of resulting complexes by way of hydrogen‐bonded synthons to form metal–organic inclusion hosts; iii) in situ inclusion of the grinding liquid in the resulting host. This approach provided quantitatively and within 20 min the known inclusion compounds of the bis(isonicotinamide) adduct in a single synthetic step. Changing the liquid phase in LAG was used to explore the inclusion behaviour of new wheel‐and‐axle adducts with nicotinamide and imidazole, revealing several inclusion compounds, as well as two polymorphs, of the bis(nicotinamide) host. Preliminary results suggest that one‐pot LAG is superior to solution synthesis in screening for metal–organic inclusion compounds. The difference between the methods is rationalised in terms of reactant solubility and solvent competition. In contrast to the nicotinamide adduct, the bis(imidazole) adduct did not form inclusion compounds. The difference in the inclusion properties of the two adducts is rationalised by structural information gathered by single crystal and powder X‐ray diffraction.     

Selective Reduction of Aryl Substituted Chalcones with Zn/Ammonium/Ethanol/Water

The selective reduction of carbon-carbon double bonds of α, β-unsaturated carbonyl compounds has attracted great interest in organic synthesis. Of many reductive systems described in the literature, transitional metal such as Pd, Rh, Pt, Ni, Cu, Ir and their complexes are usually utilized as catalysts, hydrides of Sn, Se, Te, B and sodium dithionite have been developed to catalyze selective reduction of α, β-unsaturated carbonyl compounds.     

Metal complexes of some thiocarbohydrazone ligands: synthesis and structure

The synthesis, structure, physico-chemical investigation and biological studies of some metal complexes of thiocarbohydrazone ligands are described. The ligands were obtained by condensation of N,N′-thiocarbohydrazide with carbonyl compounds such as 2-hydroxyacetophenone or 5-chlorosalicylaldehyde. A variety of binuclear or mononuclear complexes were obtained with the ligands in mono-, bi- and/or tri-deprotonated forms. The bonding sites are the azomethine nitrogen atom, phenolic oxygen atom and thiol sulfur atom. The metal complexes exhibit either tetrahedral or octahedral structures. Preliminary antimicrobial screening showed that the ligands and their metal complexes possess antimicrobial activity towards bacteria and fungi.     

Electron-impact studies of organometallic molecules—X. Some simple transition metal fluorocarbon complexes

The mass spectra of several fluoroalkyl, fluoroalkenyl and fluoroacyl complexes of manganese, rhenium, iron and ruthenium carbonyls are described. After loss of carbonyl groups, fluoroalkyl compounds eliminate an olefin, with formation of metal halide species. A trifluorovinyl complex shows a novel elimination of a carbon atom to give an ion postulated to be a difluorocarbene-metal fluoride; the occurrence of difluorocarbene-metal ions in the spectra of some related complexes is also discussed. The spectra of the acyl complexes show little evidence of elimination of the acyl carbonyl group; the major process is fission of the CO? R_f bond with loss of a fluoroalkyl radical and formation of the cationic metal carbonyl, e.g. π-C₅H₅M(CO)₃⁺ (M ? Fe or Ru). The relevance of thermal or photochemical model reactions to processes occurring in the mass spectrometer is discussed.     

Synthesis and characterization of novel chromone Schiff base complexes as p53 activators

A series of chromone Schiff base complexes were prepared and analytically as well as spectroscopically characterized. The ligand was found to act as a monobasic tridentate ligand bonded covalently or coordinatively to the metal ion via deprotonated hydroxyl group, azomethine nitrogen atom and carbonyl oxygen atom of antipyrine moiety. Both electronic spectra and magnetic measurements indicated an octahedral or a distorted octahedral geometry around the metal ions for all metal complexes except the nickel complex, which had a tetrahedral geometry. In addition, the ability of the newly prepared compounds to activate the tumour suppressor p53 in cancer cells was studied, with zinc and copper complexes showing promising activities for p53 ubiquitination compared with diphenylimidazole (reference drug).     

Cryptates—XI: Complexes macrobicycliques,formation, structure,proprietes

The macrobicyclic compounds 1–7 form inclusion complexes with alkali and alkaline-earth metal cations. In these complexes, termed cryptates, the metal cation is contained in the intramolecular cavity of the bicyclic system. The formation, the physical and spectroscopic properties and the structure of these complexes are described and discussed in detail. The formation of some complexes with the macrocyclic ligands 8a–e is also reported.     

Stereochemical analysis of constituents of essential oils and flavor compounds by enantioselective capillary gas chromatography

Modified cyclodextrins interact enantioselectively with a great variety of volatile chiral constituents of essential oils by forming diastereomeric inclusion complexes. Capillary gas chromatography is used for resolving the enantiomers of terpenoid hydrocarbons (camphene, α-pinene, limonene, α-phellandrene), carbonyl compounds (carvone, fenchone, menthone, isomenthone, piperitone, camphor, myrtenal), and alcohols (trifluoroacetylated β-citronellol, myrtenol, trans-pinocarveol, 1-octen-3-ol, and underivatized linalool). The enantiomeric composition of some of these compounds in a variety of essential oils is investigated.     

Adsorption properties of new Silochrome-based chelate-containing gas chromatographic materials

Adsorbents were obtained on the basis of Silochrome S80 modified with complex compounds of copper(II) and nickel(II) with bidentate nitrogen-containing organic ligands. The gas-chromatographic method was used to study the thermodynamic characteristics of the adsorption of organic compounds belonging to various classes on Silochrome S80 before and after its modification. It was found that supported metal complexes strongly affect the chromatographic polarity and favor a more selective separation of mixtures of close-boiling carbonyl compounds and saturated and unsaturated light hydrocarbons.     

ELECTRON TRANSFER REACTIONS OF METAL CARBONYL ANIONS

Abstract

Metal carbonyl anions exhibit one- and two-electron reactions. The two-electron processes involving transfer of groups (hydrogen, alkyl, and halogen) between metal centers are related to the nucleophilicity. The one-electron processes are primarily outer-sphere electron transfer for the metal carbonyl anions. These reactions are observed in the presence of oxidants such as coordination complexes, pyridinium salts, metal carbonyl dimers and metal carbonyl clusters. However, in contrast to organic reactions, the metal carbonyl anions may undergo inner-sphere electron transfer. Reactions of metal carbonyl anions of low nucleophilicity with metal carbonyl cations or halides are best interpreted as inner-sphere, one-electron transfer.     

Luminescent property and catalytic activity of Ru(II) carbonyl complexes containing N, O donor of 2-hydroxy-1-naphthylideneimines

The reaction of the chelating ligands (obtained by the condensation of 2-hydroxy-1-naphthaldehyde with various primary amines) with [RuHCl(CO)(EPh3)2(B)] (where E=P; B=PPh3, py or pip: E=As; B=AsPh3) in benzene afforded new stable ruthenium(II) carbonyl complexes of the general formula [Ru(Cl)(CO)(EPh3)(B)(L)] (L=anion of bidentate Schiff bases). The structure of the new complexes was investigated using elemental analyses, spectral (FT-IR, UV-vis and 1H NMR) and electrochemical studies and is found to be octahedral. All the metal complexes exhibit characteristic MLCT absorption and luminescence bands in the visible region. The luminescence efficiency of the ruthenium(II) complexes was explained based on the ligand environment around the metal ion. These complexes catalyze oxidation of primary and secondary alcohols into their corresponding carbonyl compounds in the presence of N-methylmorpholine-N-oxide (NMO) as the source of oxygen. The formation of high valent Ru(IV)=O species as a catalytic intermediate is proposed for the catalytic process.