Showing papers on "Norbornadiene published in 1997"
TL;DR: In this article, the B−H stretching vibrations of the square-planar and trigonal-bipyramidal structures of rh(μ-Cl) 2 with KTpiPr or TlTpiPr were identified.
134 citations
TL;DR: In this article, the authors used a [Rh(norbornadiene)Cl]2 catalyst in the presence of triethylamine to give poly((o-ethoxyphenyl)acetylene) (POEPA) bearing a cis-transoid form under mild conditions.
Abstract: Stereoregular polymerization of (o-ethoxyphenyl)acetylenes (OEPA) was performed using a [Rh(norbornadiene)Cl]2 catalyst in the presence of triethylamine to give poly((o-ethoxyphenyl)acetylene) (POEPA) bearing a cis-transoid form under mild conditions. The polymer underwent isomerization from the predominant cis form to the trans form when compressed at 200 kg/cm2 at room temperature. The polymers, obtained before and after the compression, were characterized in detail using laser Raman, diffuse reflective UV, ESR, and X-ray diffraction. The data suggested that the isomerization of the resulting polymer from the cis-transoid to the trans-transoid form was induced to give rise to the conjugated trans-planar zigzag structures, where unpaired electrons are stabilized as mobile electrons called solitons. The formation of the soliton radicals was confirmed by the motional narrowing of the line width observed in the ESR spectra of the compressed polymer. The trans conjugation length, n, (CC)n generated by the co...
94 citations
TL;DR: In this paper, an extensive kinetic study of this migratory alkene insertion into acyl−palladium bonds of neutral complexes containing α-diimine ligands has been carried out.
77 citations
TL;DR: In this article, the structure and chemical bonding of organic films prepared using different organic precursors were investigated using scanning tunneling microscopy, Fourier transform infrared spectroscopy, and x-ray photoelectron spectrography.
Abstract: It has been shown that well-defined, ordered organic layers can be formed on the silicon (100) surface. This is achieved through the interaction of unsaturated C=C bonds with the oriented dimers of the reconstructed Si(100)-(2×1) surface. In this article, we present an investigation of the structure and chemical bonding of organic films prepared using different organic precursors. Data were obtained using scanning tunneling microscopy, Fourier-transform infrared spectroscopy, and x-ray photoelectron spectroscopy. The molecules investigated are cyclopentene, 3-pyrroline, and norbornadiene, representing prototypical cyclic, heterocyclic, and bicyclic unsaturated organic molecules, respectively. Each molecule has at least one unsaturated C=C bond.
72 citations
TL;DR: In this article, a novel norbornadiene polymer having optically active pinanyl groups in the pendant groups was synthesized as an optical resolution membrane material, and the resulting polymer membrane showed highly enantioselective permeability for racemic propranolol used as a medicine.
53 citations
TL;DR: Combining the chemoselectivity of this process with scanning tunneling microscope nanolithography allows the formation of nanometer-sized regions having a norbonadiene adlayer as mentioned in this paper.
Abstract: Norbornadiene (bicyclo[2.2.1]Hepta-2,5-diene) is shown to chemisorb selectivity at room temperature onto clean Si(100)-2×1 surfaces. Combining the chemoselectivity of this process with scanning tunneling microscope nanolithography allows the formation of nanometer-sized regions having a norbonadiene adlayer. This concept could serve as the basis for creating spatially resolved templates to initiate chemical reactions with other chemical species in the presence of hydrogen-passivated Si(100)-2×1 areas.
45 citations
TL;DR: In this paper, a polymer containing pendant norbornadiene (NBD) moieties, P(MMA0.43-co-GMA 0.57-PNCA), and measured absorbance and refractive index spectra before and after photoisomerization of NBD moieties.
Abstract: We prepared a polymer containing pendant norbornadiene (NBD) moieties, P(MMA0.43-co-GMA0.57-PNCA), and measured absorbance and refractive index spectra before and after photoisomerization of norbornadiene moieties. Large photoinduced refractive index changes of ∼0.01 were obtained at 632.8 nm, the region far from the absorption band. A quantum yield of 0.50 was obtained for the photoisomerization of NBD moieties in this polymer. These values are sufficient to make efficient channel waveguides by photoisomerization.
45 citations
TL;DR: In this paper, four copper(I) complexes have been designed as photosensitizers for assisting the norbornadiene (NBD) → quadricyclene (Q) isomerization with the purpose of carrying out the reaction using visible light and achieving a high NBD/photocatalyst turnover.
Abstract: Four copper(I) complexes have been designed as photosensitizers for assisting the norbornadiene (NBD) → quadricyclene (Q) isomerization with the purpose of carrying out the reaction using visible light and achieving a high NBD/photocatalyst turnover. All complexes contain π-delocalized bidentate N⌒O monoanionic ligands. Their syntheses have been performed either by the metathesis reaction from CuCl or by reaction of the monoprotic ligands with Cu5Mes5 (Mes ≡ 2,4,6-Me3C6H2) in the presence of norbornadiene. The dinuclear complexes [Cu2L2(μ-NBD)], 3, [Cu2L‘2(μ-NBD)], 4, [Cu2L‘‘2(μ-NBD)], 5, and [Cu2L‘‘‘2(μ-NBD)], 6 [where L = 2-methyl-8-oxoquinolinato, L‘ = 2-methyl-5,7-dichloro-8-oxoquinolinato, L‘‘ = 4-oxoacridinato, and L‘‘‘ = 2-(2-oxo-3,5-di-tert-butyl phenyl)benzotriazole], have been isolated and characterized in the solid state, including the X-ray analysis on 3 and 6. All compounds show absorption in the visible spectrum, due to the presence of metal-to-ligand charge-transfer (MLCT) bands. Most were ...
44 citations
TL;DR: A bichromophoric compound 3β-((2-(methoxycarbonyl)bicyclo-[2.2.1]hepta-2,5-diene-3-yl)carboxy) androst-5-en-17β-yl was synthesized, and its photochem...
Abstract: A bichromophoric compound 3β-((2-(methoxycarbonyl)bicyclo-[2.2.1]hepta-2,5-diene-3-yl)carboxy)androst-5-en-17β-yl-2,2‘,6,6‘,N,N,N‘,N‘ heptamethylbenzidine (N−S−B) was synthesized, and its photochem...
43 citations
TL;DR: The reactivity of Pd−carboimine complexes toward unsaturated hydrocarbon bonds has been studied in this paper, where the insertion of norbornadiene and norbornene into the Pd −C bond of the neutral complexes (N⌒N)Pd(C(N-2,6-Me2C6H3)Me)X (X = Cl (1), Br (2), I (3); N⌌N = 2,2‘-bipyridine (bpy, a), 1,
34 citations
TL;DR: In this paper, a polyaddition of BNMA with bisphenol A diglycidyl ether (BPGE) was carried out using tetrabutylammonium bromide as a catalyst in NMP at 100 °C for 24 h, a polymer with a number average molecular weight of 18 000 was obtained in 91% yield.
Abstract: N,N'-Bis[(3-carboxynorbornadien-2-yl)carbonyl]methylenedianiline (BNMA) was synthesized in 87 % yield by the reaction of 2,5-norbornadiene-2,3-dicarboxylic acid anhydride with 4,4'-methylene-dianiline. Other dicarboxylic acid derivatives containing norbornadiene (NBD) residues were also prepared by the reaction of 2,5-NBD-2,3-dicarboxylic acid anhydride with certain diamines. When the polyaddition of BNMA with bisphenol A diglycidyl ether (BPGE) was carried out using tetrabutylammonium bromide as a catalyst in NMP at 100 °C for 24 h, a polymer with a number average molecular weight of 18 000 was obtained in 91% yield. Polyadditions of other NBD dicarboxylic acid derivatives 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. Furthermore, the photochemical reactions of the NBD poly-(ester-amide)s were evaluated in the film state or in solution. The photochemical valence isomerization of NBD residues in the polymer films proceeded smoothly to form the corresponding quadricyclane (QC) groups upon irradiation with sunlight. The photochemical reversion of the resulting QC groups in the polymer films proceeded efficiently by irradiation of 272 nm light. The stored energy in the QC groups of the polymers was evaluated to be about 84 kJ/mol by DSC measurement of the irradiated polymer films.
TL;DR: In this article, the reaction of dimethyl sulfide ditriflate with alkenes leads to the corresponding sulfonium salts, and the dependence of the reaction course on the substrate structure is discussed.
TL;DR: In this article, the crystal structure of fac-[Mo(CO)3(SPPhPy2-S,N2] was determined by area detector diffractometry and showed that the coordination at molybdenum is essentially octahedral but with trigonal elongation.
Abstract: The final products of the reactions of either [Mo(CO)6] or [Mo(CO)4(NBD)] (NBD = norbornadiene) with PPy3 (Py = 2-pyridyl) or ZPPy3 (Z = O, S, ClAu, C6F5Au) are fac-[Mo(CO)3(Py3P-N3)] or fac-[Mo(CO)3(Py3PZ-N3)], where the ligands act as tridentate N-donors. The use of ZPPhPy2 (Z = O, S) leads to fac-[Mo(CO)3(ZPPhPy2-Z,N2)], the ligands acting as tridentate Z,N2-donors. The crystal structure of fac-[Mo(CO)3(SPPhPy2-S,N2)] was determined by area detector diffractometry and shows that the coordination at molybdenum is essentially octahedral but with trigonal elongation. Some tetracarbonyl complexes which are intermediates in the formation of the above tricarbonyl complexes have been isolated (cis-[Mo(CO)4(PPy3-P)2] and cis-[Mo(CO)4(ZPPhPy2-Z,N)] (Z = O, S)) or detected (cis-[Mo(CO)4(Py3P-N2)] and cis-[Mo(CO)4(SPPy3-S,N)]). The syntheses of the new complexes [Au(C6F5)(PRPy2-P)] (R = Py or Ph) are also described.
TL;DR: In this paper, the structure of WCl(SnCl3)(CO)3(η4-NBD) was characterized and the IR, 13C NMR spectra of 2 were also described and correlated with the crystallographically observed geometry.
TL;DR: In this article, the authors used a [Rh(norbornadiene)CI]2 catalyst in alcohol and triethylamine to transform p-methylethynylbenzene (MEB) to columnar structures.
Abstract: Stereoregular polymerization of p-methylethynylbenzene (MEB) was successfully performed using a [Rh(norbornadiene)CI]2 catalyst in alcohol and triethylamine. Polymers which have a cis-transoid structure were selectively formed in fairly high yields. The structure and properties of the resulting polymers were compared with those of polyethylnylbenzene (PEB) by means of x-ray diffraction and ESR techniques. The data showed that both pristine amorphous polymers are converted to pseudohexagonal structures called columnar when they were treated with toluene at room temperature. The line width, ΔH msl in the ESR spectrum of PMEB polymer was found to be increased from 10.5–12.5 gauss to 13.1–15.8 gauss when the solvent was changed from alcohols, e.g., ethanol or tert-butanol, to cyclic alcohols, e.g., cyclopentanol. The increase of the observed ΔH msl was explained in terms of magnetically inhomogeneous broadening arising from heterogeneous aggregations of radical spins in the columnar polymer phase.
TL;DR: The number-averaged molecular weights of these materials were determined by GPC−LS to be 34 000 for 8 and 75µ000 for 14, respectively as discussed by the authors.
Abstract: Soluble precursor polymers 8 and 14 were successfully synthesized via the palladium-mediated condensation of 4,4‘-(1,3,2-dioxaborolan-2-yl)biphenyl (7) with the bis(p-bromophenyl)norbornadiene monomer 5 and the bis(p-bromophenyl)norbornene monomer 13, respectively. The number-averaged molecular weights of these materials were determined by GPC−LS to be 34 000 for 8 and 75 000 for 14. Thermolysis of 8 by a retro-Diels−Alder reaction began at 260 °C and appeared (by GC−MS analysis of the volatile byproducts) to yield a conjugated polymer with both alkyne and cyclopentadiene functionalities in the polymer backbone; however, TGA analysis indicated that the transformation was accompanied by some decomposition. The analogous thermolysis of 14 to yield the polymer with a double bond in the backbone began at 230 °C and appeared to proceed without the concomitant decomposition.
TL;DR: In this paper, the main group metal salt MgCl2 can give rise to oligomerization and polymerization of olefins, and the properties and structure of these polymers correspond to those prepared by ring-opening metathesis polymerization.
Abstract: Until now polymerization catalysis was linked to transition metal chemistry with only few exceptions. However, in our work we will show that the main group metal salt MgCl2 can give rise to oligomerization and polymerization of olefins. Since the late 1960s MgCl2 has been used as support material for commercial Ziegler-Natta catalysts in many variations. Although the influence of this ‘inert’ support on the structure and properties of the resulting polymers is known, investigations of the reactivity of MgCl2 with olefins are rare. Surprisingly MgCl2 polymerizes strained olefins like norbornene, norbornadiene, 5,6-dichloronorbornene and bistrifluoromethyltricyclo[4.2.2.0]decatriene in high yield to high molecular weight products. The polymers are characterized by FT-IR, NMR, size exclusion chromatography (GPC) and thermoanalytical methods. The properties and structure of these polymers correspond to those prepared by ring-opening metathesis polymerization (ROMP). The characterization of different MgCl2 phases is carried out by the use of powder diffraction measurements, electron microscopy, measurements of the specific surface (BET), simultaneous thermal analysis (STA), and atomic absorption spectroscopy (AAS).
TL;DR: In this paper, the utility of two Rh(III) diimine complexes, Rh(phen)33+ and Rh(phi)2(phen)-3+ (phen = 1,10phenanthroline, phi = 9,10-phenanthrenequinone diimines), as sensitizers for the interconversion of norbornadiene (N) and quadricyclane (Q) has been investigated using steady-state photochemical and laser flash photolysis (LFP) techniques.
Abstract: The utility of two Rh(III) diimine complexes, Rh(phen)33+ and Rh(phi)2(phen)3+ (phen = 1,10-phenanthroline, phi = 9,10-phenanthrenequinone diimine), as sensitizers for the interconversion of norbornadiene (N) and quadricyclane (Q) has been investigated using steady-state photochemical and laser flash photolysis (LFP) techniques. Irradiation of acetonitrile solutions of Rh(phen)33+ and N causes slow conversion to Q. The reaction is reversible; irradiation of Rh(phen)33+ in the presence of Q leads to N. Irradiation of acetonitrile solutions of Rh(phi)2(phen)3+ and Q yields N. However, this reaction is irreversible; irradiation of the Rh(III) complex in the presence of N fails to afford Q. Irradiation of methanol solutions of either Rh(III) complex in the presence of N or Q affords minor amounts of two methanol-C7 adducts but fails to quench the N−Q interconversion reaction. The results are consistent with N−Q interconversion via an exciplex intermediate. The Rh(III)-sensitized deazatization of two cyclic az...
TL;DR: Dipole 1 is cleaved by HCl, giving the corresponding (thioxophosphoranyl)diazomethane 15, while addition of HCl to 2a leads to hydrazonoyl chloride 16, in 70% isolated yield.
Abstract: N-[Bis(diisopropylamino)phosphino]-C-[bis(diisopropylamino)thioxophosphoranyl]nitrilimine (1) reacts with electron-poor dipolarophiles such as maleimide, methyl vinyl ketone, and 1,4-naphthoquinone via HOMO(dipole)-controlled [2+3] cycloadditions, while N-[bis(diisopropylamino)(methyl)phosphonio]-C-[bis(diisopropylamino)thioxophosphoranyl]nitrilimine (2a) reacts with electron-rich dipolarophiles such as norbornadiene and ethyl trans-pyrrolineacrylate via LUMO(dipole)-controlled [2+3] cycloadditions. Carbon disulfide reacts with 1 via a formal [4+2] cycloaddition leading to phosphazene containing heterocycle 11 in 75% yield. Dipole 1 is cleaved by HCl, giving the corresponding (thioxophosphoranyl)diazomethane 15, while addition of HCl to 2a leads to hydrazonoyl chloride 16, in 70% isolated yield. Hydrazone 17' (95%) and phosphazine 18(80%) are obtained by a 1,3-addition of BuLi to 1 and PhOLi to 2a, respectively. Trimethylphosphine reacts with 2a by a phosphine-carbene coupling reaction, giving the ylide 20 which is isolated in 75% yield.
TL;DR: In this article, the adduct between tri-n-butylphosphine and carbon disulfide 1 with norbornene gives the novel zwitterionic structure 9. In solution this dissociates to the ylide which undergoes Wittig reaction with aldehydes.
TL;DR: In this paper, 3.5-(3-Cyclohexen-1-yl)-2-norbornene [CHNB] has been shown to form a very lightly crosslinked polymer with good elongation via ring-opening metathesis polymerization (ROMP).
Abstract: 5-(3-Cyclohexen-1-yl)-2-norbornene [CHNB] has been shown to form a very lightly crosslinked polymer (Tg = 127°C) with good elongation via ring-opening metathesis polymerization (ROMP). Based on swelling behavior with added norbornadiene dimer, the low crosslink density is ascribed to ≪0.5% participation by the cyclohexenyl ring. Compared to dicyclopentadiene (DCPD), CHNB polymerizations were less exothermic, required less catalyst, and exhibited greater molding latitude, which are advantageous for Reaction Injection Molding (RIM). Styrene-isoprene and styrene-ethylene/butylene block copolymers were effective impact modifiers for polyCHNB, forming large particle morphologies. Small rubber particles formed from styrene-butadiene block copolymers were not effective for impact enhancement of polyCHNB, in contrast to polyDCPD. Rubber-modified polyCHNB retained impact resistance four to six times longer than polyDCPD samples when aged in air at 50–70°C. Related RIM-ROMP of liquid monomer mixtures prepared by cyclopentadiene cycloadditions with 4-vinyl-1-cyclohexene, cis-1,3-divinylcyclopentane, 3,5-divinylcyclopentene or cis-2,4-divinylbicyclo[3.3.0]oct-6-ene formed highly crosslinked, less ductile copolymers with Tgs as high as 206°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3049–3063, 1997
TL;DR: The heterocubane [Rh(μ3-I)(C4H4BPh)]4 (2a) readily adds Lewis bases to form the mononuclear products as mentioned in this paper.
TL;DR: In this article, the tri-n-butylphosphine/carbon disulfide adduct with norbornene and aromatic di- and trialdehydes gives the bis- and tris-dithiolanes resulting from Wittig reaction of 2.
TL;DR: Novel biphotochromic systems containing two norbornadiene moieties in one molecule or one norbornadienyl group in 2-N-(3-phenylnorbornadienes-2-carbonyl)]-N-arylaminomethylene-(2H) benzo[b]thiophenones have been prepared under UV/VIS irradiation as mentioned in this paper.
Abstract: Novel biphotochromic systems containing two norbornadiene moieties in one molecule or one norbornadienyl group in 2-N-(3-phenylnorbornadiene-2-carbonyl)]-N-arylaminomethylene-(2H) benzo[b]thiophenones have been prepared Under UV/VIS irradiation the latter compounds undergo Z/E-isomerktion acompanied by N → O acyl rearrangement and valence isomerization in the norbornadiene fragment Bis-norbornadienyl derivatives upon irradiation convert through stepwise isomerization into corresponding quadricyclanes The back reactions are catalyzed with trifluoroacetic acid at room temperature
Patent•
08 Jul 1997
TL;DR: In this article, the problem of obtaining a novel polymeric substance having unique optical functions by selecting a polymer mainly consisting of specified structural units is addressed, where the groups represented by formula I and formula II in formula III are selected from groups of formula IV, and X is selected from among NH2 and like groups.
Abstract: PROBLEM TO BE SOLVED: To obtain a novel polymeric substance having unique optical functions by selecting a polymer mainly consisting of specified structural units. SOLUTION: An acetylene derivative monomer represented by formula I (wherein formula II is a 5-14C aryl or heteroaryl; X is a releasable H or a t-amino-containing substituent having a molecular weight of 100 or below) is polymerized at -98 to +120 deg.C for 1-50hr in the presence of a polymerization catalyst being a compound of a transition metal such as W, Mo, Ru or Rh, desirably a transition metal complex catalyst such as [RhCl(NBD)]2 (wherein NBD is norbornadiene) in a solvent (e.g. benzene or diethyl ether) inert to the starting monomer, the polymer to be formed and the catalyst to obtain an acetylene derivative polymer mainly consisting of structural units represented by formula III (wherein group II and X are defined as above) and having a degree of polymerization of 5 or above. The groups represented by formula I and formula II in formula III are selected from groups of formula IV, and X is selected from among NH2 and like groups. It is particularly desirable that formula II is formula V and X is COOH.
TL;DR: The reaction of S4N4 with phosphines of the type PhPR2 (1,5) and PhR′PR [6−11 (R′ = dicyclohexylamino), R: 1,6 = pyrrolidino, 2,7 = piperidino; 3,8 = morpholino; 4,9 = N-methylpiperazino; 5,10 = hexamethylenimino; and 11 = anilino] afford the phosphiniminocyclotrithiazene
Abstract: The reactions of S4N4 with phosphines of the type PhPR2 (1–5) and PhR′PR [6–11 (R′ = dicyclohexylamino), R: 1,6 = pyrrolidino; 2,7 = piperidino; 3,8 = morpholino; 4,9 = N-methylpiperazino; 5,10 = hexamethylenimino; and 11 = anilino] afford the phosphiniminocyclotrithiazene derivatives, 12–22 at room temperature. Only in the case of the phosphine 10 was the disubstituted derivative 23 isolated (in 65% yield). The trithiazene derivatives of the chiral phosphines in refluxing CH3CN produce the acyclic compounds PN–S3N, 24–27 in ca. 60% yield. Norbornadiene reacts at room temperature with the cyclotrithiazene derivatives to give the addition products 28–35. P=N–S3N3 derivatives are found to be stable in 2M NaOH. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 225–232, 1997.
TL;DR: Deltacyclenes and deltacyclanes produced from the homo Diels-Alder reaction of norbornadiene are opened to the corresponding biquinanes as mentioned in this paper.
TL;DR: In this paper, a suspension of commercial WCl 4 initiates rapid polymerization of norbornene and norbornadiene under mild conditions, if norbornenyl acetate is used as a substrate, and homogeneous polymerization occurs.
Abstract: A suspension of commercial WCl 4 initiates rapid polymerization of norbornene and norbornadiene under mild conditions. If norbornenyl acetate is used as a substrate, WCl 4 is dissolved and homogeneous polymerization occurs. In both cases polymers ( M w = about 80 000 ), the structure of which corresponds to the ring-opening metathesis mode of polymerization, were prepared. WCl 4 has also been found to polymerize monosubstituted acetylenes (benzene, 50°C). Poly( t -butylacetylene) of M w = 600 000 , poly(phenylacetylene) of M w = 200 000 and poly(1-hexyne) of M w = 14 000 were prepared in high yields. When WCl 4 was dissolved in the reaction with oxygen-containing compounds (e.g. methyl acetate, acetylacetone, acetophenone) before substrate addition, catalyst activity increased significantly. WCl 4 in 1,4-dioxane was found to be a very active system for phenylacetylene polymerization; it polymerizes this monomer at the monomer-to-catalyst mole ratio equal to 1000 providing polymer of M w = 400 000 .