Photoinduced Pyramidal Inversion Behavior of Phosphanes Involved with Aggregation-Induced Emission Behavior

Aggregation-induced emission (AIE) is a fascinating phenomenon because of the applications of luminescent materials in the aggregated state, which exploit the large structural changes of the molecules in the excited state. Recently, it was reported that triphenylphosphane derivatives show AIE behavior in which they undergo potentially large structural changes in the excited state. Inspired by this report, photoinduced pyramidal inversion behavior of phosphanes was investigated. In photochemical experiments, the prepared P-stereogenic phosphanes exhibited photoracemization in dilute solution, and a negative correlation was observed between the photoracemization and the AIE phenomenon. Theoretical computations revealed that the inversion barrier in the excited state was much smaller than that in the ground state. This is the first report on the photoinduced pyramidal inversion behavior of phosphanes, which will provide new and unexplored applications.     

Cobaltocenium Carboxylate Transition Metal Complexes: Synthesis,Structure, Reactivity,and Cytotoxicity

Cobaltocenium carboxylate is an unusual betaine that functions as a formally neutral carboxylate ligand with late transition metal centers comprising Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Rh⁺. Structurally, a rich coordination chemistry is observed – from simple monomeric homoleptic complexes to heteroleptic dimeric, trimeric, and polymeric compounds, as shown by X‐ray diffraction of 11 compounds. Chemically, thermal decarboxylation was investigated aiming at the formation of cobaltocenium‐carbene transition metal complexes, in analogy to such chemistry of imidazolium carboxylate betaines. Cytotoxicity studies of cobaltocenium carboxylate transition metal complexes were performed to evaluate the medicinal bioorganometallic potential of these compounds. While cobaltocenium carboxylate was inactive, its complexes with Ag⁺, Cd²⁺, and Hg²⁺ triggered significant cytotoxic effects.     

Transition Metal Complexes with Organoazide Ligands: Synthesis,Structural Chemistry,and Reactivity

A drastically enhanced stability is observed for organoazides (RN₃) in the presence of Cu²⁺ or Pd²⁺ when the azido group is included in a ligand system chelating the transition metal ions. X-ray structure analysis of such complexes (the structure of a cyclohexaneazide palladium complex is depicted) confirms that the alkylated nitrogen atom of the N₃ moiety is coordinated to the transition metal center.     

Synthesis and Reactivity of Fluoro(Organyl)Phosphanes

Abstract

A new method for producing fluoro(organyl) phosphanes is presented. They are prepared by Cl/F-exchange from the corresponding chloro compounds using Et₃N.nHF as a fluorinating agent. Phosphanyl fluorophospharanes, R₂P-PR₂F₂, are found to be intermediates of the disproportionation of Fluoro (diorganyl) phosphanes. R₂PF react with aldehydes to form phosphinito phosphoranes, R₂PF₂-CHR'-OPR₂. Oxaphospholenes are formed in their reaction with α, β- unsaturated aldehydes. Furthermore, the reactions with 1.2-diketones, carboxylic acid derivatives, and covalent azides are described.     

Transition Metal Catalysts in the Synthesis of Functionalized Substituted Phosphonates

Abstract

Synthesis of new functionalized phosphonates was achieved by two ways, using either nucleophilic or electrophilic modification of organophosphorus compounds by transition metal catalytic reactions The first way employs the transformation of carbonyl group in α, β, and y-ketophosphonates by nucleophilic addition (silacyanation, hydrosilylation, etc).     

过渡金属重卡拜的合成、结构与反应性

过渡金属硅卡拜、锗卡拜、锡卡拜和铅卡拜是过渡金属分别与硅、锗、锡和铅之间形成三键的化合物。自从1996年首次发现钼锗卡拜以来,相继得到了一系列过渡金属锗卡拜、锡卡拜和铅卡拜化合物,而首例过渡金属硅卡拜则于2010年得以成功制备,标志着过渡金属与第14族元素之间形成三键的空白被全部填满。这些化合物的出现大大丰富和完善了过渡金属主族元素化学在成键、结构和反应方面的内容,引起化学界的重视。本文结合这方面最新的实验研究进展,系统全面总结了这些化合物的合成、结构和反应性,并对该领域的发展前景作了讨论。     

Reactivity of Alkyne-Substituted Transition Metal Clusters: An Overview

In this work we present a summary of reactivity studies of alkyne substituted transition metal clusters towards different nucleophilic and electrophilic reagents. This work is not comprehensive but includes some of the most representative types of reactions of this type of compounds.     

Phenyl Silicates with Substituted Catecholate Ligands: Synthesis,Structural Studies and Reactivity

While the generation of aryl radicals by photoredox catalysis under reductive conditions is well documented, it has remained challenging under an oxidative pathway. Because of the easy photo-oxidation of alkyl bis-catecholato silicates, a general study of phenyl silicates bearing substituted catecholate ligands has been achieved. The newly synthesized phenyl silicates have been fully characterized, and their reactivity has been explored. It was found that, thanks to the substitution of the catecholate moiety, notably with the 4-cyanocatecholato ligand, the phenyl radical could be generated and trapped. Computational studies provided a rationale for these findings.     

Recent Studies of the Synthesis and Reactivity of Group 6 and 7 Transition Metal Compounds with Metal–Metal Bonds

Metal–metal bonded dinuclear compounds of Group 6 and 7 transition metals with several primary structural motifs and their reactivity toward halides and organic molecules are reviewed. The reactivities of dinuclear compounds of Cr, Mo, W, Mn, Tc, and Re are discussed in context with reaction types (ligand metathesis, oxidative addition), the types of ligands (carbon, sulfur or nitrogen containing), or the ligand substituted in the original starting material (carbonyl). Since the depth and breadth of the chemistry is extensive, the categories are fairly general and some overlap between ligand types and reaction types occurs. A brief history followed by recent studies of each of these transition metal centers provides a general overview of the reactivity of these metal–metal bonded systems.     

Gas Phase Ion Chemistry of Transition Metal Clusters: Production, Reactivity, and Catalysis

This review focuses on the use of mass spectrometry to examine the gas phase ion chemistry of metal clusters. Ways of forming gas phase clusters are briefly overviewed and then the gas phase chemistry of silver clusters is discussed to illustrate the concepts of magic numbers and how reactivity can be size dependent. The chemistry of other bare and ligated metal clusters is examined, including mixed metal dimer ions as models for microalloys. Metal clusters that catalyze gas phase chemical reactions such as the oxidation of CO and organic substrates are reviewed. Finally the interface between nanotechnology and mass spectrometry is also considered.     

过渡金属取代的钨铝杂多配合物的制备、表征和性质

用分步设计法合成了以铝为中心原子的过渡元素与钨的三元杂多配合物,经ICP、TG分析确定其化学式为K_4，6，7[AlM(OH₂)W₁₁O₃₉]·xH₂O(M=V⁵⁺、Cr³⁺、Mn²⁺、Fe³⁺、Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Cd²⁺)。采用IR、UV、XRD、¹⁸³W和²⁷Al NMR等对配合物的结构进行了表征,表明配合物具有Keggin结构；循环伏安法对该系列配合物的氧化还原性质研究表明,其氧化还原过程为不可逆的两电子还原,配合物的磁化率测试均表现为顺磁性,还对其热稳定性进行了讨论。     

含过渡金属HMS的合成和催化性能

利用中性伯胺（十二胺）作模板剂,合成了过渡金属Ｃｕ、Ｔｉ、Ｃｏ、Ｆｅ取代的ＨＭＳ中孔材料,ＸＲＤ和ＦＴ＝ＩＲ表征表明,Ｃｕ、Ｔｉ能有效地嵌入ＨＭＳ骨架壁中而不会造成其中孔有序度的下降;而Ｃｏ、Ｆｅ的嵌入会明显降低表面活性剂的模板组装作用,从而造成中孔结晶有序度的显著下降,催化实验结果表明：Ｃｕ－ＨＭＳ、Ｆｅ－Ｓｉｌｉｃａ是苯要不要羟基化的有效催化剂,而Ｔｉ－ＨＭＳ则是苯乙烯环氧化的有效催化剂。     

Synthesis and Reactivity of Substituted N-Hydroxy-1,4-dihydro-1,4-azaphosphorins

Abstract

The synthesis of substituted N-hydroxy-1,4-dihydro-1,4-azaphosphorins 4 has been carried out by adding the di (trimethylsilyl)peroxide 3 to the anion 2 generated from the addition of n-butyllithium to compound 1.     

Synthesis,Structure, and Reactivity of Metal Complexes with Alkoxysilylmethyl Ligands

The synthesis and properties of the new metal complexes 1 , 6 – 12 with alkoxysilylmethy substituents (RO–SiR′₂–CH₂–ML_n) is described. The complexes 14 , 15 and 18 with a chloromethylsiloxy ligand were also prepared. These molecules should serve as starting compounds for the synthesis of metallasilaoxetanes. Several reactions which should lead to these new metallacycles have been performed, but it was never possible to isolate them or to proof their existence spectroscopically. However, chloride abstraction from (C₅H₅)₂Ti(Cl)CH₂Si(CH₃)₂O^tBu ( 7 ) by silver cations led to the activation of the Si–O–R group. This indicates an interaction of the oxygen atom with the metal atom, but there was no proof for the intermediate formation of a four membered metallacycle.     

Synthesis and Characterization of Transition Metal

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Kinetics and Mechanism of Styrene Oxidation Using Transition Metal Substituted Dodecatungstophosphate

Tetraalkylammonium (TAA) salts of transition metal substituted dodecatungstophosphate, (TAA)5PW11O39.H₂O (where TAA = (C₂H₅)4N (TEA), (C3H7)4N (TPA), and (C₄H9)4N (TBA), and M = Mn ₂+ , Fe ₂+ and Co₂ ) catalyzed the oxidation of styrene with H₂O₂ at 353 K. Except for the Mn ₂+ salt, other TAA salts were found to be active and gave mainly benzaldehyde and styrene oxide products. Among the catalyst tested, TBA (tetrabutylammonium) salt of Co ₂+ was more active in styrene oxidation. Kinetics of TBA-PW11CoO₃₉ catalyzed oxidation of styrene have been investigated and mehanism for oxidation of styrene has been proposed.     

Oxygen-17 NMR, Electronic, and Vibrational Spectroscopy of Transition Metal Peroxo Complexes: Correlation with Reactivity

The (17)O NMR chemical shifts of several previously characterized mono- and diperoxo complexes of vanadium(V), molybdenum(VI), tungsten(VI), and titanium(IV) were measured. Compilation of NMR, electronic, and vibrational spectroscopic data and metric parameters for these and other complexes permits us to draw correlations among (17)O peroxo chemical shift, the electronic charge transfer band, the O-O vibrational frequency, and the length of the oxygen-oxygen bond. Monoperoxo complexes exhibit (17)O chemical shifts of 500-660 ppm, while those of diperoxo complexes fall in the range 350-460 ppm. The correlation of chemical shift with the inverse ligand-to-metal charge transfer energy from electronic spectra is consistent with a formalism developed by Ramsey, despite the variations in the metals, the number of peroxo ligands, and the nature of the remaining ligands in the coordination sphere. Vibrational frequency and length of the oxygen-oxygen bond also correlate with the inverse ligand-to-metal charge transfer energy. Monoperoxo complexes show values of nu(O)(-)(O) above 900 cm(-)(1) and O-O distances in the range 1.43-1.46 ?. Diperoxo complexes have values of nu(O)(-)(O) below 900 cm(-)(1) and O-O distances of 1.46-1.53 ?. The assignment of nu(O)(-)(O) = 910 cm(-)(1) for the infrared spectrum of ammonium aquaoxoperoxo(pyridine-2,6-dicarboxylato)vanadium(V), NH(4)[VO(O(2))(dipic)(H(2)O)], was made by isotopic substitution. The stretching frequency and length of the O-O bond for peroxo complexes are explained in terms of sigma-bonding between a metal d orbital and a peroxo pi orbital. A comparison of the spectroscopic properties of these complexes with their reactivity as oxidizing agents suggests that the strength of the O-O bond is an important factor. The most reactive species exhibit lambda(max) values below 400 nm, stretching frequencies below 900 cm(-)(1), and (17)O chemical shifts below 600 nm. These generalizations may permit the prediction of peroxometal reactivity from spectroscopic information.