Norbornadiene

About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.

The chemical and electrochemical one-electron oxidation of diamidonaphthalene-bridged complexes; paramagnetic [Rh2]3+-containing A-frames

Abstract: The complexes [Rh2L4{µ-2,3-(NH)2C10H6}][1; L2=(CO)(PPh3) or η4-cod (cyclo-octa-1,5-diene)] and [Rh2L4{µ-1,8-(NH)2C10H6}][2; L2=(CO)(PPh3), η4-cod, η4-nbd (norbornadiene), or η4-tfbb (tetrafluorobenzobarrelene)] undergo two sequential one-electron oxidations at a platinum bead electrode. At –78 °C, the chemical oxidation of compound (1; L2=η4-cod) or (2; L2=η4-cod) in thf, with [CPh3][BF4] in CH2Cl2, gives the [Rh2]3+-containing salts [Rh2(η4-cod)2(η-L1)][BF4][1+; L1= 2,3-(NH)2C10H6 or 2+; L1= 1,8-(NH)2C10H6] which, in tetrahydrofuran (thf)-CH2Cl2 mixtures at –196 °C, show solvent-dependent e.s.r. spectra implying thf co-ordination at one axial site. The irreversible one-electron reduction of [Rh2(NO)(η4-cod)2{µ-1,8-(NH)2C10H6}][PF6](3), prepared from (2;L2=η4-cod) and [NO][PF6] in CH2Cl2, leads to the loss of NO and the regeneration of (2; L2=η4-cod).

Mechanistic studies of the molybdenum-catalyzed asymmetric alkylation reaction

Abstract: Enantiomerically enriched, deuterated branched carbonates (Z)-(S)-PhCH(OCO2Me)-CH = CHD (1-D), (Z)-(R)-PhCH(OCO2Me)CH = CHD (2-D), and linear carbonate (E)-(S)-PhCH = CHCHD(OCO2Me) (3-D) were used as probes in the Mo-catalyzed asymmetric allylic alkylation with sodium dimethyl malonate, catalyzed by ligand-complex 11 derived from the mixed benzamide/picolinamide of (S,S)-transdiaminocyclohexane and (norbornadiene)Mo(CO)4. The results of these studies, along with x-ray crystallography and solution NMR structural analysis of the π-allyl intermediate, conclusively established the reaction proceeded by a retention–retention pathway. This mechanism contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed by an inversion–inversion pathway. A proposed rationale for the retention pathway for nucleophilic substitution involves CO-coordination to form a tri-CO intermediate, followed by complexation with the anion of dimethyl malonate to produce a seven-coordinate intermediate, which reductively eliminates to afford product with retention of configuration.

Origin of the color of π‐conjugated columnar polymers: Poly(p‐n‐octylthiophenyl)acetylene prepared using a [Rh(norbornadiene)Cl]2 catalyst

Abstract: Highly stereospecific polymerization of a novel sulfur containing aromatic acetylenes, that is, (p-n-octylthiophenyl)acetylene (pOctSPA), was successfully performed using the Rh complex, [Rh(norbornadiene)Cl]2-TEA, catalyst in the presence of various solvents under mild conditions. The resulting polymers were characterized in detail by 1H NMR, ESR, laser Raman, diffuse reflective UV-Vis (DRUV-Vis), and wide angle X-ray diffraction methods. The data showed that the resulting polymers bear cis-transoid form, which can induce the cis-to-trans isomerization when the cis polymers are subjected to pressure at room temperature under vacuum, breaking rotationally the cis CC bonds in the main-chain giving two kinds of π-radicals, the so-called cis radical and trans radical as the origin of a polymer magnet like a novel spin glass material. Further, the resulting cis poly(acetylene)s were found to have a helical main-chain, which is packed in pseudohexagonal crystal called π-conjugated columnar or nano π-conjugated columnar as a novel color controllable material. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2836–2850, 2005

Photogenerated catalysis by transition-metal complexes. Photoacceleration of the valence isomerization of quadricyclene to norbornadiene in the presence of PdCl2(.eta.4-norbornadiene)

Abstract: Isomerisation de valence du quadricyclane (Q) en norbornadiene acceleree par irradiation a 313 nm en presence du catalyseur complexe PdCl 2 (η 4 -norbornadiene). Le rendement quantique peut exceder 10 2 et depend de la concentration de Q, de l'intensite lumineuse et du solvant. Mecanisme de reaction en chaine redox

Metallomacrocycles that incorporate cofacially aligned diimide units.

Abstract: Pyromellitic diimide and naphthalene diimide moieties were incorporated into hemilabile phosphanylalkyl thioether ligands. These ligands reacted with [Cu(CH3CN)4]PF6 and [Rh(NBD)Cl]2 (NBD = norbornadiene) by the weak-link approach to form condensed intermediates. Upon reaction of each diimide ligand with these transition-metal precursors, the two diimide units became cofacially aligned within a supramolecular macrocyclic architecture. The introduction of ancillary ligands to each of these condensed intermediates caused the weak thioether-metal bonds to break, thus generating a large macrocycle in which the distance between diimide units is significantly larger than for the condensed intermediates. The two Rh(I) cationic condensed intermediates were characterized by single-crystal X-ray diffraction studies, and the electrochemical activity of these macrocycles was demonstrated with the naphthalene diimide-Cu(I) macrocycles.