Showing papers on "Norbornadiene published in 1999"
TL;DR: In this article, the authors used a Rh complex, [Rh(norbornadiene)Cl] 2, as a catalyst, and the resulting polyacetylenes were characterized in detail by 1 H NMR, ESR, laser Raman, diffuse reflective UV, and wide-angle X-ray diffraction.
Abstract: Stereospecific polymerization of monosubstituted acetylenes was successfully performed using a Rh complex, [Rh(norbornadiene)Cl] 2 , as a catalyst, and the resulting polyacetylenes were characterized in detail by 1 H NMR, ESR, laser Raman, diffuse reflective UV, and wide-angle X-ray diffraction. The Rh complex was found to yield selectively the cis-transoid isomer even at room temperature in high yields when alcohol or triethylamine was used as the solvent. Additionally, the resulting cis-polyacetylenes were found to form a pseudohexagonal, columnar self-assembly or superstructure. Further compression of the cis-polymers induced cis-trans isomerization even at room temperature under vacuum, breaking rotationally the cis-C=C bonds and, thus, giving π-radicals as the origin of magnetic properties.
201 citations
TL;DR: In this paper, the reaction of (η5-pentamethylcyclopentadienyl)gallium (Cp*Ga) with Ni(COD)2 (COD = 1,5-cyclooctadiene) and NorM(CO)4 (Nor = norbornadiene; M = Cr, Mo) was studied.
82 citations
TL;DR: In this paper, the structure of PCTD was determined by X-ray analysis of its derivative, AgOTf(PCTD), derived via endo−endo dimerization of 2,5-norbornadiene, which is a major product in the reaction in DMSO.
Abstract: Bicyclo[2.2.1]hepta-2,5-diene (2,5-norbornadiene) dimerizes in the presence of a catalytic amount of Ru(1-2:5-6-η-cyclooctadiene)(1-6-η-cyclooctatriene) (Ru(cod)(cot)) and an electron-deficient olefin such as N,N-dimethylacrylamide, dimethyl fumarate, or dimethyl maleate in toluene or tetrahydrofuran (THF) to give a new compound, pentacyclo[6.6.0.02,6.03,13.010,14]tetradeca-4,11-diene (PCTD), in high yield along with a small amount of a known endo−endo dimer, heptacyclo[6.6.0.02,6.03,13.04,11.05,9.010,14]tetradecane (HCTD), which is a major product in the reaction in DMSO. Ru(cod)(cot)-dimethyl fumarate in THF was the most efficient catalyst, and the yield of PCTD was 96% even at 40 °C. The structure of PCTD was determined by X-ray analysis of its derivative, [AgOTf(PCTD)]n. PCTD was found to be derived via endo−endo dimerization of 2,5-norbornadiene. Formation of PCTD from two molecules of 2,5-norbornadiene involves the cleavage of two carbon−carbon bonds. Dimerization of 7-tert-butoxy-2,5-norbornadiene ...
66 citations
Patent•
02 Nov 1999
TL;DR: In this paper, a constrained geometry complex catalyst and an activating cocatalyst are used for shear-thinning ethylene/α-olefin/diene monomer interpolymers.
Abstract: Shear-thinning ethylene/α-olefin and ethylene/α-olefin/diene monomer interpolymers that do not include a traditional branch-inducing monomer such as norbornadiene are prepared at an elevated temperature in an atmosphere that has little or no hydrogen using a constrained geometry complex catalyst and an activating cocatalyst.
60 citations
TL;DR: In this article, high-resolution scanning tunneling microscopy has been used to investigate the adsorption of a variety of unsaturated organic molecules on the (001) surface of silicon and germanium.
Abstract: High-resolution scanning tunneling microscopy has been used to investigate the adsorption of a variety of unsaturated organic molecules on the (001) surface of silicon and germanium. Results are presented for a number of prototypical alkenes, conjugated and non-conjugated dienes, and aromatic compounds. These include cyclopentene, 1,5-cyclooctadiene, norbornadiene, 2,3-dimethyl-1,3-butadiene, and benzene on the Si(001) surface, and for cyclopentene on the Ge(001) surface. Factors controlling the selectivity of various reaction pathways and the consequences for preparation of ordered organic overlayers are discussed.
55 citations
TL;DR: In this article, the authors show that cyclization of cyclopentane derivatives is induced by zinc and acid or by BuSnH4, depending on the relative intensity of the 19 F NMR spectrum with relative intensities of 3:2.
46 citations
TL;DR: In this paper, the authors report on the bond coupled electron transfer (BCET) isomerization reaction of norbornadiene (NB) to quadricyclane (Q).
Abstract: In this paper, we report on the bond coupled electron transfer (BCET) isomerization reaction of norbornadiene (NB) to quadricyclane (Q). We have used several triplet sensitizers to examine electron...
45 citations
TL;DR: The tetrathioperrhenate anion, ReS4- (1), is shown to form adducts with a variety of alkenes as discussed by the authors, including norbornene and norbornadiene.
Abstract: The tetrathioperrhenate anion, ReS4- (1), is shown to form adducts with a variety of alkenes. The alkene adducts form reversibly, and those of norbornene and norbornadiene were isolated. For norbor...
39 citations
TL;DR: In this article, a novel clay catalyst containing a heterogenized Rh(I) triphenylphosphine complex (Rh-bentonite) has been prepared via ion exchange of a Hungarian Na+-Bentonite with Wilkinson complex.
Abstract: A novel clay catalyst containing a heterogenized Rh(I) triphenylphosphine complex (Rh-bentonite) has been prepared via ion exchange of a Hungarian Na+-bentonite with Wilkinson complex [RhCl(PPh3)3]. It was established that the active species [Rh(PPh3)]+ was situated on the external surface of the catalyst, which was found to be efficient in the liquid-phase hydrogenation of 1-octene, cyclohexene, norbornadiene, 1,5-cyclooctadiene, phenylacetylene and cyclohexene-3-one.
28 citations
TL;DR: In this paper, the ground state of norbornadiene bound to the photosensitizer was studied with the hybrid B3LYP functional and the main bonding interaction between the ligand and the metal was π back-donation, metal to ligand, which reduced the π−π* band gap in nor bornadiene.
Abstract: Density functional calculations with the hybrid B3LYP functional have been used to study the ground state of norbornadiene bound to the photosensitizer [Cu(8-oxoquinolinato)]. The main bonding interaction between the ligand and the metal is π back-donation, metal to ligand, which reduces the π−π* band gap in norbornadiene. CIS calculations performed on free norbornadiene and on the system where norbornadiene interacts with the photosensitizer have shown that the photosensitizer reduces the excitation energy to promote the system to the first excited singlet state. In terms of wavelength, this difference implies that light with λ almost 100 nm longer can be used to photoactivate the norbornadiene with respect to free norbornadiene.
28 citations
TL;DR: In this article, the authors show that the head-to-head dimerization is thermodynamically favored over the headto-tail by about 14 kcal/mol in the case of α, β-unsaturated selenoaldehydes and selenoketones.
Abstract: The reactions of α,β-unsaturated aldehydes and ketones with bis(dimethylaluminum) selenide, (Me2Al)2Se, yield the corresponding α,β-unsaturated selenoaldehydes and selenoketones. They are too unstable to be isolated in the monomeric form, but they undergo regioselective [4 + 2] dimerization via a “head-to-head” oriented transition state to afford diselenin derivatives (trans and cis isomers). Theoretical calculations at the density functional theory level show that this selectivity occurs because the “head-to-head” dimerization is thermodynamically favored over the “head-to-tail” by about 14 kcal/mol. Both dimerization reactions have low energy barriers: 1.5 and 2.8 kcal/mol for the former and 0.9 and 1.3 kcal/mol for the latter. In the presence of norbornadiene, these compounds function as 4π heterodienes (CC−CSe) to give the respective cycloadduct products. On the other hand, they act as 2π dienophiles (CSe) in the reactions with cyclopentadiene except for selenoacrolein which serves as a 4π diene and ...
TL;DR: Efficient routes to the synthesis of norbornadiene-tethered nitrile oxides have been developed, and their intramolecular 1,3-dipolar cycloadditions were studied and were found to be highly regio- and stereoselective.
TL;DR: In this article, the X-ray crystal structure of complex 1a has been determined and shows a distorted square planar geometry in which one BIAN ligand is coordinated in a bidentate fashion (PdN(1)=2.037(4) A; PdN(2)= 2.189(4), and, interestingly, the other BAN ligand in a unidentate manner (PdaN(3)=2
TL;DR: In this article, the standard enthalpies of isomerization, hydrogenation, and formation of norbornadiene, quadricyclane, norbornene, nortriclyn, and norbornan were calculated.
Abstract: We have calculated the standard enthalpies of isomerization, hydrogenation, and formation (ΔhydH298, ΔisomH298, and ΔfH298) of norbornadiene, quadricyclane, norbornene, nortricyclane, and norbornan...
TL;DR: Ferrocenyl dithiadiphosphetane disulfide behaves as RPS2 in simple cycloaddition reactions as mentioned in this paper, giving rise to fused 4-membered C2PS ring compounds.
Abstract: Ferrocenyl dithiadiphosphetane disulfide behaves as RPS2 in simple cycloaddition reactions. Reactions with norbornadiene, norbornene and hexamethyl dewar benzene all give rise to fused 4-membered C2PS ring compounds. Reaction with 2,3-dimethylbutadiene gave a simple Diels–Alder adduct which undergoes further reaction with BuLi and RX to yield FcP(S)(SR)(C6H9) (R = CH2Ph, o-MeC6H4CH2, 2,4-dinitrophenyl). A trithiaphosphorinane was obtained when Fc2P2S4 was reacted with benzaldehyde or trimethylacetaldehyde. Reaction of Fc2P2S4 with PhCH2N CHPh gave a dithiophospholane and a thiazadiphosphetane disulfide. The new compounds have been characterised spectroscopically with illustrative examples having been studied by X-ray crystallography.
TL;DR: In this article, Copolymerization of ethylene with a symmetrical diene, namely, 2,5-norbornadiene, was studied using a homogeneous metallocene/MAO catalyst system.
Abstract: Copolymerization of ethylene with a symmetrical diene, namely, 2,5-norbornadiene was studied using a homogeneous metallocene/MAO catalyst system. Copolymerizations were found to occur exclusively through one of the two equally reactive endocyclic double bonds with Cp 2 ZrCl 2 , (buCp) 2 ZrCl 2 and Et(Ind) 2 ZrCl 2 catalysts. Both double bonds are involved in the polymerization when Me 2 SiCp 2 ZrCl 2 is used as the catalyst. In the case of Et(Ind) 2 ZrCl 2 , the incorporation of the diene was found to increase with time. The extent of incorporation of the diene, molecular weight and copolymerization activity were found to depend on the nature of the catalyst.
TL;DR: In this article, the insertion reaction of CO migratory insertion into the Pd-oxanorbornyl bond of pure 5a,b occurs and leads to the acyl complexes (OC)3Fwe{µ-Si(OMe)2.2.
Abstract: [(OC)3Fwe{µ-Si(OMe)2(OMe)}(µ-dppm)Pzd{C(2O)Me}] (1a) (dppm=Ph2PCH2PPh2) to afford the heterodinuclear complexes [(OC)3{(MeO)3Si}Fwe(µ-dppm)Pzdw{C7H10C(2Oz)Me}] (2) and [(OC)3{(MeO)3Si}- Fwe(µ-dppm)Pzdw{C7H8C(2Oz)Me}] (3), respectively. In these insertion products, the alkoxysilyl ligand has become terminally bound whereas a dative bond between the acetyl oxygen and the metal allows the square-planar Pd centre to achieve a 16e configuration, thus resulting in a five-membered Pwd–C–C–C–Oz ring. This chemistry was extended to chiral olefins and when the dppm and dppa complexes 1a,b were reacted with a 9:1 mixture of (±)-(2-cyano-7-oxabicyclo[2.2.1]hept-5-ene-2-endo-yl and -2-exo-yl acetate (4,4′), the stable insertion products [(OC)3Fwe{µ-Si(OMe)2(OMe)}(µ-Ph2PXPPh2)Pzdw{C9H9NO3C(2Oz)Me}] (5a,5a′ X=CH2; 5b,5b′ X=NH) were isolated in high yield. A high stereo- and regioselectivity was found for these metallacarbonylations. Spectroscopic data as well as X-ray diffraction studies show that in contrast to 2 and 3, the µ2-η2-Si–O interaction present in the precursors 1a,b is retained in 5a,b. The Pd atom adopts a pseudo square-pyramidal coordination resulting from an additional weak ketonic interaction with the 5-exo-acetyl group of the 2-endo-acetoxy-2-cyano-7-oxabicyclo[2.2.1]hept-5-exo-yl moiety, which leads to the formation of a five-membered chelate ring. Electronic effects are invoked to account for these different structural features. Under a carbon monoxide atmosphere, CO migratory insertion into the Pd–oxanorbornyl bond of pure 5a,b occurs and leads to the acyl complexes [(OC)3Fwe{µ-Si(OMe)2(OMe)}(µ-Ph2PXPPh2)Pzd{C(2O)C9H9NO3C(2O)Me}] (6a X=CH2; 6b X=NH). These successive insertion reactions constitute the first elementary steps on the way to polyketone chain growth mediated by a bimetallic system.
TL;DR: In this paper, transition metal-catalyzed reactions of norbornadiene with secondary amines were reported, where the secondary amine was replaced by a transition metal atom.
TL;DR: In this article, a complete account of the intermolecular and intramolecular Pauson-Khand reactions of N-(2-alkynoyl) derivatives of chiral 2-oxazolidinones is presented.
TL;DR: A conjugated polymer carrying organometallic pendant groups, poly[4-(ferrocenylethynyl)phenylacetylene], has been prepared as discussed by the authors, and the 13 C NMR, IR, UV-vis and Raman spectra of the monomer and polymers are reported.
Abstract: A new conjugated polymer carrying organometallic pendant groups, poly[4-(ferrocenylethynyl)phenylacetylene], has been prepared. [Rh(nbd)(OCH 3 )] 2 as a catalyst (nbd = norbornadiene) provides a mixture of an insoluble polymer (yield 71%) free of C≡CH groups and soluble oligomers (yield 22%, MW ca. 1100). WOCl 4 /2Me 4 Sn as a catalyst provides almost exclusively a polymer (yield 60%, M w = 32. 10 3 ) containing a small amount of C≡CH groups that is soluble in aromatic and low-polarity solvents. Its solubility, however, decreases upon storage in the solid state, probably due to a subsequent crosslinking. The 13 C NMR, IR, UV-vis and Raman spectra of the monomer and polymers are reported.
TL;DR: In this article, a density functional theory computational study was carried out on the hydration and amination of alkenes to give alcohols and amines respectively, and it was shown that both reactions are exothermic.
TL;DR: In this article, the norbornadiene-fused dihydrotetrathiafulvalenes (DTEVenes) were used to obtain the bis-adducts for less reactive acetylenic dipolarophiles.
TL;DR: In this article, the molecular structures of aminoborylphosphanes were determined by single crystal X-ray diffraction techniques, and the structures of (i Pr 2 N) 2 BP(H)SiPh 3 ·Cr(CO) 5 ( 4 ) and [( i Pr 2 n) 2BP(H)] 2 SiMe 2 ·W(CO), 4 ( 5′ ) have been determined.
TL;DR: In this paper, trifluoromethyl (CF3)-substituted NBD derivatives, which not only produce thermally stable QC derivatives but also absorb visible light efficiently, were synthesized.
Abstract: Trifluoromethyl (CF3)-substituted NBD derivatives, which not only produce thermally stable QC derivatives but also absorb visible light efficiently, were synthesized. These NBD derivatives exhibited efficient fatigue resistance.
TL;DR: In this paper, the Pd/Cu-catalyzed three-component ternary coupling reaction of aryl halides, norbornadiene, and alkynols in the presence of aqueous NaOH and a phase transfer catalyst in toluene at 100 °C in high yields.
Abstract: 2,3-Disubstituted norbornenes were obtained by the Pd/Cu-catalyzed three-component ternary coupling reaction of aryl halides, norbornadiene, and alkynols in the presence of aqueous NaOH and a phase transfer catalyst in toluene at 100 °C in high yields.
TL;DR: In this paper, the norbornadiene/ethylene copolymerization was studied using [Ph 2 C(Ind)(Cp)ZrCl 2 ] and [Cp 2 ZrCl2 ] catalysts in the presence of methylaluminoxane as a cocatalyst.
Abstract: The norbornadiene/ethylene copolymerization was studied using [Ph 2 C(Ind)(Cp)ZrCl 2 ] and [Cp 2 ZrCl 2 ] catalysts in the presence of methylaluminoxane as a cocatalyst. The polymerizations were carried out using a semiflow method, and the comonomer was charged batchwise into the reactor. Polymerizations were run at 60 °C at an ethylene pressure of 2.5 bar. The activities of both catalysts decreased when the norbornadiene/ethylene ratio in the reaction increased. The structural characterization of the copolymer was performed by DEPT and 1 H- 13 C 2D NMR experiments. The copolymerization of norbornadiene was shown to occur via both double bonds of norbornadiene. The polymers with high norbornadiene content were amorphous and transparent.
TL;DR: In this paper, a series of bis(1-R%-2-R-3-R)-trisubstituted cyclopentadienyl)zirconium dichlorides 3 (RR%Ph), 4(RPh, R%Me), 21(Rn-Bu), R% Me, 22(R t-Bu, R % Me), 23(R (CH2)4OMe), R %Me), and 24(R n-Bu) were determined by X-ray crystallography.
Journal Article•
TL;DR: In this paper, the syn and anti isomers of benzotris(norbornadiene) 7, the only molecules that include both features known to lead to bond length alternation in benzenes, i.e., bicyclic ring strain and π-π interaction, have been synthesized from 2,3-dibromonorbornadienes using butyllithium and copper(I) iodide.
Abstract: The hitherto unknown syn and anti isomers of benzotris(norbornadiene) 7, the only molecules that include both features known to lead to bond length alternation in benzenes, i.e. bicyclic ring strain and π–π interaction, have been synthesized from 2,3-dibromonorbornadiene using butyllithium and copper(I) iodide.
TL;DR: The reactivity of the quadricyclane under electron transfer conditions (Ar3N+, 20°C, 98% yield) changes drastically upon epoxidation of the isopropylidene group as discussed by the authors.
Abstract: Little change, large impact: The reactivity of the quadricyclane 1 under electron transfer conditions (Ar3N+, 20 °C, 98 % yield) changes drastically upon epoxidation of the isopropylidene group. Instead of the bicycloheptadiene 2, the norbornadiene 4 is formed spontaneously and quantitatively. Theoretical calculations explain why. R=CH2OCH3, CH2OCH2CH2OCH3.
TL;DR: In this paper, a polymer with number average molecular weight of 69,800 was synthesized in 70% yield by the reaction of 2,5-norbornadiene-2,3-dicarboxylic acid anhydride with N,N′-diphenylethylenediamine.
Abstract: N,N′-Bis[(3-carboxynorbornadien-2-yl)carbonyl]-N,N′-diphenylethylenediamine (BNPE) was synthesized in 70% yield by the reaction of 2,5-norbornadiene-2,3-dicarboxylic acid anhydride with N,N′-diphenylethylenediamine. Other dicarboxylic acid derivatives containing norbornadiene (NBD) residues having N,N′-disubstituted amide groups were also prepared by the reaction of 2,5-NBD-2,3-dicarboxylic acid anhydride with certain secondary diamines. When the polyaddition of BNPE with bisphenol A diglycidyl ether (BPGE) was carried out using tetrabutylammonium bromide as a catalyst in N-methyl-2-pyrrolidone at 100°C for 12 h, a polymer with number average molecular weight of 69,800 was obtained in 98% yield. Polyadditions of other NBD dicarboxylic acid derivatives containing N,N′-disubstituted amide groups with BPGE were also performed under the same conditions. The reaction proceeded very smoothly to give the corresponding NBD poly(ester–amide)s in good yields. Photochemical reactions of the obtained polymers with N,N′-disubstituted amide groups on the NBD residue were examined, and it was found that these polymers were effectively sensitized by adding appropriate photosensitizers such as 4-(N,N-dimethylamino)benzophenone and 4,4′-bis(N,N-diethylamino)benzophenone in the film state. The stored energies in the quadricyclane groups of the polymers were also evaluated to be about 94 kJ/mol by DSC measurement of the irradiated polymer films. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 917–926, 1999