377 research outputs found
Early Cretaceous continental delamination in the Yangtze Block: evidence from high-Mg adakitic intrusions along the Tanlu fault, central Eastern China
No full textAbstract not availableLiqiong Jia, Xuanxue Mo, M. Santosh, Zhusen Yang, Dan Yang, Guochen Dong, Liang Wang, Xinchun Wang, Xuan W
Complexes of Group 7 Metals with Metal-Carbon Sigma and Multiple Bonds
No full textGroup 7 metals, especially manganese and rhenium, form a large number of organometallic compounds with metal-carbon σ-bonds and/or metal-carbon multiple bonds, including alkyl, aryl, alkenyl, alkynyl, acyl, carbene (alkylidene) and carbyne (alkylidyne) complexes. These compounds display rich chemical reactivities and can play an important role in stoichiometric synthesis, catalysis and materials sciences. This chapter summarizes the synthesis, structure, and reactivity of these compounds reported in the literature in the period of 2005–19.</p
Chemistry of Metallabenzynes and Rhenabenzenes
No full textThis chapter first aims to summarize authors' work in the development of chemistry of rhenabenzenes, metallabenzenes containing a group 7 metal. It also aims to summarize their progress in the development of the chemistry of metallabenzynes. The original route to make metallabenzynes involves the reactions of the osmium complex OsCl2(PPh3)3 with alkynes. Nucleophiles can add to metallabenzynes. The reactivity and regioselectivity of these reactions are dependent on the ligands as well as the substituents on the metallacycle. Rearrangement of metallabenzenes to cyclopentadienyl complexes is one of the common reactivities of metallabenzenes. A series of metallabenzynes with Os or Re are isolated. These metallacycles can be regarded as aromatic compounds based on the criteria of electronic structure, geometry, reactivity, aromatic stabilization energy (ASE), and magnetic properties. They show reactivity of both aromatic systems (e.g. they can undergo electrophilic substitution reaction) and organometallic compounds (e.g. they can undergo migratory insertion reactions to form carbene complexes).</p
Synthesis and reactivity of ruthenium-hydride complexes containing chelating triphosphines and studies on ruthenium-chloride, acetate, and carbonyl complexes containing chelating triphosphines /
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Recent progress in the chemistry of osmium carbyne and metallabenzyne complexes
No full textThere has been much research activity in the chemistry of osmium complexes with an osmium-carbon triple bond. This paper summarizes recent progress in the synthesis, reactivities, and structural properties of osmium carbyne and osmabenzynes complexes.</p
Progress in the chemistry of metallabenzynes
No full textThe synthesis and chemical and structural properties of metallabenzynes are reviewed. Reaction of [OsCl2(PPh3)3) 3] with HC≡CSiMe3 produces the osmabenzyne [Os(≡CC(SiMe3)=C(CH3)C(SiMe3)= CH)Cl 2(PPh3)2], which undergoes electrophilic substitution reactions with HBF4 and Br2 to give new osmabenzynes. The reactivities and the X-ray diffraction data of osmabenzynes indicate that these metallacycles have aromatic properties. Unlike benzyne, which is thermally unstable, osmabenzynes are thermally much more stable and can be stored for months at room temperature without decomposition. The higher thermal stability of osmabenzynes compared to benzyne can be related to the relatively smaller ring strain and larger conjugation energy.</p
Our Journey to the chemistry of metallabenzynes
No full textThis personal account summarizes our work on the chemistry of transition-metal-containing metallabenzynes, organometallic compounds derived from formal replacement of a C atom in benzyne by an isolobal transition-metal fragment. Metallabenzynes with osmium and rhenium have been synthesized and well characterized. They have aromatic character on the basis of the criteria of reactivity, geometry, aromatic stabilization energy, and magnetic properties. They can undergo typical reactions of aromatic systems (e.g., electrophilic substitution reactions) and organometallic complexes (e.g., reductive elimination reactions to form carbene complexes).</p
Dynamic multi-cue tracking with detection responses association
No full textMulti-cue integration has proved successful at increasing the robustness of tracking algorithms and overcoming the failure cases of individual cue. But considering dynamic appearance of objects or clutter background, the integration based on constant weights may weaken the performance of this scheme. In this paper, we propose a dynamic weights update mechanism for multiple cues tracking with detection responses as supervision. We integrate multiple cues based on the observation hypotheses compared with detection association results and adjust the weights according to the approximation degree. The integration is adapted on-the-fly during tracking, in order to keep the tracker adaptive. The proposed method allows flexible combination of different cues and we select cues based on color and local feature for tracking. Experiments are carried out on 602 trajectories extracted from TRECVID 2008 event detection dataset which is recorded in an airport scenario. Comparison results prove the effectiveness of our method. ? 2010 ACM.EI
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