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Norbornadiene
About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.
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TL;DR: In this paper, the triplet-triplet energy transfer mechanism was used for the photoisomerization of cis-and trans-piperylene with high quantum efficiency by Cu(diphos)BH/sub 4/ and Cu(prophos), BH/ sub 4/ (1,2-bis(diphenylphosphino)ethane).
Abstract: Photoisomerization of cis- and trans-piperylene can be sensitized with high quantum efficiency by Cu(diphos)BH/sub 4/ (diphos is 1,2-bis(diphenylphosphino)ethane) and Cu(prophos)BH/sub 4/ (prophos is 1,3-bis(diphenylphosphino)propane). Sensitization is accompanied by quenching of the emissive /sup 3/(/sigma/-a/sub /pi//) excited state in each copper(I) complex, and the two processes occur with identical Stern-Volmer kinetics. Measurements of the trans/cis diene ratio at the photostationary state can be used to estimate the triplet-state energy as 60-61 kcal for Cu(diphos)BH/sub 4/ and > 61 kcal for Cu(prophos)BH/sub 4/; additional evidence suggests that 66-67 kcal is a reasonable value for the latter complex. Collectively, the results support the assignment of triplet-triplet energy transfer as the primary mechanism for sensitization and quenching in these systems. This mechanism also can accommodate earlier reports that Cu(diphos)BH/sub 4/ and Cu(prophos)BH/sub 4/ sensitize the valence isomerization of norbornadiene to quadricyclene with markedly different quantum efficiencies. 17 refs., 6 figs., 2 tabs.
37 citations
TL;DR: In the presence of a trapping agent, α,β-unsaturated selenoaldehydes and selenoketones, generated in situ by selenation of corresponding carbonyl compounds with bis[dimethylaluminum) selenide, underwent regioselective self-condensation to yield cyclic diselenide derivatives as discussed by the authors.
37 citations
TL;DR: The reduction of Ni(S2C2(CF3)2)2(C7H8) (3) proceeds by an overall two-electron irreversible process through an ECE mechanism.
Abstract: The reduction of Ni(S2C2(CF3)2)2(C7H8) (3) proceeds by an overall two-electron irreversible process through an ECE mechanism. The reduction potential of 3 is about 700 mV negative of that in an earlier report, which is shown to result from contamination of the sample by the monoanion of the olefin-free complex [Ni(S2C2(CF3)2)2]-.
37 citations
TL;DR: In this article, a small degree of polarization of the π-olefin-Pd bond in the transition state for the σ-allyl migration is interpreted in terms of the polarization of a σallylic carbon atom from Pd to the coordinated olefin in a concerted cis-exo addition of PdC across the double bond.
37 citations
TL;DR: In this article, polynorbornadiene and polynorbornene were synthesized via ring opening metathesis polymerization (ROMP) with [RuCl 2 (PPh 3 ) 2 (amine)] as catalyst precursors, amine=piperidine ( 1 ) or perhydroazepine ( 2 ) in the presence of 5μL of EDA.
Abstract: Polynorbornadiene and polynorbornene were synthesized via ring opening metathesis polymerization (ROMP) with [RuCl 2 (PPh 3 ) 2 (amine)] as catalyst precursors, amine = piperidine ( 1 ) or perhydroazepine ( 2 ) in the presence of 5 μL of ethyl diazoacetate (EDA) ([monomer]/[Ru] = 5000; 40 °C with 1 ; 25 °C with 2 ). The effects of the solvent volume (2–8 mL of CHCl 3 ), reaction time (5–120 min) and atmosphere type (argon and air) on the yields were investigated to observe the behavior of the two different precursors. Quantitative yields were obtained for 60 or 120 min regardless of the starting volumes, either in argon or air, with both Ru species. However, low yields were obtained for short times (5–30 min) when the reactions are performed with large volumes (6–8 mL). In argon, the yields were larger with 2 , associated to a faster propagation reaction controlled by the Ru active species. In air, the yields were larger with 1 , associated to a higher resistance to O 2 of the starting and propagating Ru species. The different activities between 1 and 2 are discussed considering the steric hindrance and electronic characteristics of the amines such as ancillary ligands and their arrangements with PPh 3 and Cl − ions in the metal centers.
37 citations