Structure and reactivity of mono(cyclopentadienyl)vanadium alkynyl and aryne complexes

Starting from CpVCl(2)(PMe(3))(2) (1) the paramagnetic mono- and bis(phenylethynyl) complexes CpVCl(2-n)(C=CPh)(n)(PMe(3))(2) [n=1 (2), 2 (3)] have been synthesized. Both compounds were characterized by X-ray diffraction and were found to be thermally more stable than other CpV(III) hydrocarbyl complexes. The CpV(III) bis(phenyl) complex CpVPh(2)(PMe(3))(2) (5) decomposes at ambient temperature through beta-hydrogen abstraction to give the first isolated vanadium benzyne complex, CPV(eta(2)-C6H4)(PMe(3))(2) (6). The molecular structure of 6 indicates that this compound can best be described as a high-spin d(2) vanadium(III) benzometallacyclopropene. The cyclopropene character is expressed in the reactivity of 6, showing insertion of unsaturated substrates. Insertion of diphenylacetylene gives CpV(eta(2)-PhC=CPhC(6)H(4))(PMe(3))(2) (7), with a planar vanadaindene structure, whereas terminal alkenes CH2=CRR' (R = H, Me; R' = H, Me) insert regioselectively to give beta-substituted metallaindanes CpV(eta(2)-CH(2)CRR'C6H4)PMe(3) (R and R' = H, 8a; R = H, R' = Me, 8b; R and R' = Me, 8c), which show a low thermal stability in case one of the beta-substituents is a hydrogen. With t-BuCN double insertion followed by rearrangement of the intermediate diazametallacycle gives the isoindolenine-substituted vanadium(III) imido complex CpV[NC(t-Bu)N=C(t-Bu)C6H4](PMe(3))(2) (9). The benzyne complex 6 reacts with dihydrogen to form the known triple-decker CpV(C6H6)VCp through partial hydrogenation of the benzyne ligand

An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts

Chemistry of Mesoporous Molecular Sieves

Applied Science