Showing papers on "Norbornadiene published in 2015"
TL;DR: DFT calculations suggest that the molecular zwitterions within these structures are all significantly more stable than their corresponding σ-alkane cations, suggesting that the solid-state motif has a strong influence on their observed relative stabilities.
Abstract: The use of solid/gas and single-crystal to single-crystal synthetic routes is reported for the synthesis and characterization of a number of σ-alkane complexes: [Rh(R2P(CH2)nPR2)(η2,η2-C7H12)][BArF4]; R = Cy, n = 2; R = iPr, n = 2,3; Ar = 3,5-C6H3(CF3)2. These norbornane adducts are formed by simple hydrogenation of the corresponding norbornadiene precursor in the solid state. For R = Cy (n = 2), the resulting complex is remarkably stable (months at 298 K), allowing for full characterization using single-crystal X-ray diffraction. The solid-state structure shows no disorder, and the structural metrics can be accurately determined, while the 1H chemical shifts of the Rh···H–C motif can be determined using solid-state NMR spectroscopy. DFT calculations show that the bonding between the metal fragment and the alkane can be best characterized as a three-center, two-electron interaction, of which σCH → Rh donation is the major component. The other alkane complexes exhibit solid-state 31P NMR data consistent wi...
69 citations
TL;DR: In this paper, sterically hindered amido-digermynes with a variety of olefins and related molecules are investigated, leading to facile reduction, C-H activation, dehydrogenation, and cycloaddition of the unsaturated substrate.
55 citations
TL;DR: The results demonstrate that Co-bisphosphane systems are sufficiently reactive and that they lead to high selectivity in the intermolecular process and the first catalytic system with useful levels of enantioselection for the reaction of norbornadiene and trimethylsilylacetylene.
36 citations
TL;DR: In this paper, the synthesis of cyclopentadiene derivatives starting from norbornadiene was investigated using dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate.
27 citations
TL;DR: In this paper, the synthesis, spectroscopy, structures and chemical reactivity of platinum(II) diolefin complexes cis-[(∥∧∥)PtCl2], cis[∧ ∥)ptCl(R)] and cis-[∥ ∧∩)ptsCl(2] have been explored.
Abstract: The synthesis, spectroscopy, structures and chemical reactivity of platinum(II) diolefin complexes cis-[(∥∧∥)PtCl2], cis-[(∥∧∥)PtCl(R)] and cis-[(∥∧∥)Pt(R)2] [∥∧∥ = chelate diolefin ligand: 1,5-cyclooctadiene (COD), 1,5-dimethylocta-1,5-diene (Me2COD), norbornadiene (NBD), 1,5-hexadiene (HEX), 3-allyloxypropene (All2O, diallyl ether), diallylamine (All2NH); R = Me, Bn, C6F5, C6F4H-4 (or -5), or C≡C(4-Me)Ph] have been explored. The relative exchange rates of the cis-[(∥∧∥)PtCl2] complexes towards the diimine ligand diisopropyl-1,4-diazabutadiene (iPr-DAB) increased along the series COD < Me2COD < NBD < HEX < All2O by a factor of 4. The presumably dimeric complex [(All2NH)PtCl2]2 undergoes a unique rearrangement process in dimethyl sulfoxide (DMSO) solution to yield the dimeric piperazine complex [PtCl(dmso)(C6H10N)]2, which has been characterised by single-crystal XRD. For selected platinum complexes, cytotoxic effects in HT-29 colon carcinoma and MCF-7 breast cancer cell lines were evaluated. For comparison, the dicationic complexes [(COD)Pt(Bn)(L)][PF6]2 with the very labile coligands N-methyl-4,4′-bipyridinium (MQ+) and N-methyl-1,4-pyrazinium (Mpz+) were added to the study. Although the hexadiene complexes [(HEX)Pt(C6F4H-4)2] and [(HEX)Pt(C6F4H-5)2] show strong cytotoxicity, the introduction of labile diolefin ligands or the labile cationic MQ+ or Mpz+ coligands does not generally lead to markedly increased cytotoxicity.
25 citations
TL;DR: In this article, the in situ procedure for neutral dimeric μ2-X-bridged diphosphine rhodium complexes of the type [{Rh(diphine)(μ 2-X)}2] (X=Cl, OH) are usually prepared by the addition of diphine ligands to the Rhodium complex.
Abstract: As the workhorses for many applications, neutral dimeric μ2-X-bridged diphosphine rhodium complexes of the type [{Rh(diphosphine)(μ2-X)}2] (X=Cl, OH) are usually prepared in situ by the addition of diphosphine ligands to the rhodium complex [{Rh(diolefin)(μ2-X)}2] (diolefin=cyclooctadiene (cod) or norbornadiene (nbd)) or [{Rh(monoolefin)2(μ2-Cl)}2] (monoolefin=cyclooctene (coe) or ethylene (C2H4)). The in situ procedure has been investigated for the diphosphines 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP), 5,5′-bis(diphenylphosphino)-4,4′-bi-1,3-benzodioxole (SEGPHOS), 5,5′-bis[di(3,5-xylyl)phosphino]-4,4′-bi-1,3-benzodioxole (DM-SEGPHOS), 5,5′-bis[di(3,5-di-tert-butyl-4-methoxyphenyl)phosphino]-4,4′-bi-1,3-benzodioxole (DTBM-SEGPHOS), 2,2′-bis(diphenylphosphino)-1,1′-dicyclopentane (BICP), 1-[2-(diphenylphosphino)ferrocenyl]ethyldi-tert-butylphosphine (PPF-PtBu2), 1,1′-bis(diisopropylphosphino)ferrocene (DiPPF), 1,2-bis(diphenylphosphino)ethane (DPPE), 1,2-bis(o-methoxyphenylphosphino)ethane (DIPAMP), 4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxalane (DIOP), 1,2-bis(2,5-dimethylphospholano)benzene (Me-DuPHOS), 1,4-bis(diphenylphosphino)butane (DPPB), and 1,3-bis(diphenylphosphino)propane (DPPP); the resulting complexes have been characterized by 31P NMR spectroscopy and, in most cases, also by X-ray analysis. Depending on the diphosphine ligand, the solvent, the temperature, and the rhodium precursor, species other than the desired one [{Rh(diphosphine)(μ2-X)}2] are formed, for example, [(diolefin)Rh(μ2-Cl)2Rh(diphosphine)], [Rh(diphosphine)(diolefin)]+, [Rh(diphosphine)2]+, and [Rh(diphosphine)(diolefin)(Cl)]. The results clearly show that the in situ method commonly applied for precatalyst preparation cannot be regarded as an optimal strategy for the formation of such neutral [{Rh(diphosphine)(μ2-X)}2] complexes.
23 citations
TL;DR: The most successful initiators were of the type Mo(NR)(CHCMe2Ph)[OCMe(CF3)2]2 (R = 2.6-Me2C6H3 (1) or 2,6-i-Pr2C 6H3(2) as discussed by the authors.
20 citations
19 citations
TL;DR: The reactions of ozone with three bicyclic alkenes, α-pinene, norbornene, and norbornadiene, were studied by low-temperature (14 K), argon matrix isolation infrared spectroscopy including (18)O isotope-labeling studies and no evidence for "unusual" chemistry, prompted by the bicyclic nature of the reactants was observed.
Abstract: The reactions of ozone with three bicyclic alkenes, α-pinene, norbornene, and norbornadiene, were studied by low-temperature (14 K), argon matrix isolation infrared spectroscopy including (18)O isotope-labeling studies. Theoretical calculations of some of the proposed reaction intermediates and products were carried out using the Gaussian 09 suite of programs, applying density functional theory (DFT), the B3LYP functional, and the 6-311G++(d,2p) basis set. In the α-pinene/ozone system, the thermal reaction between α-pinene and ozone was too slow to observe under the twin-jet or merged-jet deposition conditions of these experiments. However, red light (λ ≥ 600 nm) irradiation of the argon matrixes containing α-pinene and ozone caused new infrared peaks to appear that could be readily assigned to reaction products of α-pinene with O((3)P) resulting from ozone photolysis: α-pinene oxide (with an epoxide ring) and two isomeric ketones. Norbornene and norbornadiene were both found to react with ozone in the gas phase during twin-jet or merged-jet deposition of these mixtures with argon. New peaks observed in the infrared spectra were assigned to the primary ozonides, Criegee intermediates, and secondary ozonides of norbornene and norbornadiene, indicating that the bulk of these reactions proceeded via the "classic" Criegee mechanism for ozonolysis of alkenes. Calculated infrared frequencies and molecular energies support these conclusions. Ultraviolet irradiation of these mixtures resulted in complete decomposition of the early intermediates and the formation of acids, aldehydes, alcohols, carbon dioxide, and carbon monoxide. In any case, no evidence for "unusual" chemistry, prompted by the bicyclic nature of the reactants, was observed.
16 citations
TL;DR: In this paper, a monomer-dimer equilibrium with the mononuclear complex [Rh{κ2-N,O-N(Dipp)C(O)tBu}(NBD)] (3b) was established for the first time.
16 citations
TL;DR: Reaction of the amidate ligand salt with tol-d8 solution of E/Z-,, or / results in 2,6-diisopropylphenylisocyanate extrusion providing the corresponding [Rh]-C6F5 complex in good yield.
Abstract: Reaction of the amidate ligand salt, Na[N(Dipp)C(O)C6F5] (1) (Dipp = 2,6-diisopropylphenyl) with [Rh(NBD)Cl]2 (NBD = norbornadiene) results in formation of the dirhodium(I) complex [Rh2{μ2-N,O-N(Dipp)C(O)C6F5}2(NBD)2] (2). Reaction of 2 with PCy3 at room temperature provides an equilibrium mixture of the geometric isomers (E/Z)-[Rh{κ1-O-N(Dipp)C(O)C6F5}(NBD)(PCy3)] (E/Z-3). Treatment of 2 with 3 equiv. of CNXyl (Xyl = 2,6-dimethylphenyl) gives the κ1-O complex [Rh{κ1-O-N(Dipp)C(O)C6F5}(CNXyl)3] (6) while use of 3 equiv. of PPh3 provides the κ2-complex [Rh{κ2-N,O-N(Dipp)C(O)C6F5}(PPh3)2] (8). For complex κ2-N,O8, an equilibrium results with free PPh3 giving the κ1-O complex [Rh{κ1-O-N(Dipp)C(O)C6F5}(PPh3)3] (9). Heating a tol-d8 solution of E/Z-3, 6, or 8/9 results in 2,6-diisopropylphenylisocyanate extrusion providing the corresponding [Rh]-C6F5 complex in good yield.
TL;DR: In this paper, the preparation of ring opening metathesis polymerization (ROMP) monomers using a 1,3-dipolar cycloaddition between aryl azides and norbornadiene is described.
Abstract: The preparation of new ring opening metathesis polymerization (ROMP) monomers using a 1,3-dipolar cycloaddition between aryl azides and norbornadiene is described. Various norbornenetriazolines, obtained through a solvent-and catalyst-free reaction, can subsequently be incorporated into polymer backbones through ROMP reactions. Furthermore, thermal decomposition of the triazoline moiety can allow for further polymer functionalization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2357–2362
TL;DR: In this paper, a 5.5-exo-Selective reductive Mizoroki-Heck reaction of 4-tert-butyl-1-chlorobenzene with 2,5-norbornadiene has been achieved by [PdCl2(PCy3)2]/HCO2Na to give 5.
Abstract: 5-exo-Selective reductive Mizoroki–Heck reaction of 4-tert-butyl-1-chlorobenzene with 2,5-norbornadiene has been achieved by [PdCl2(PCy3)2]/HCO2Na to give 5-exo-(4-tert-butylphenyl)-2-norbornene in...
TL;DR: D density functional theory is employed to study new subphthalocyanine based receptors which feature the 1,4-dithiino and norbornadiene linkages and a hydrogen-bonded capsule can bind C 60 with an unprecedented affinity.
TL;DR: In this paper, an experimental and computational approach was employed to study the mechanisms of the palladium-promoted hydroalkynation and [2+1] cycloaddition, which may have important implications for other palladiumcatalyzed transfor- mations especially those involving phosphapalladacycles and phosphinous acid-phosphinito-containing palladium complexes.
Abstract: Whereas the reaction of norbornadiene with terminal alkynes in the presence of a phosphapalladacycle catalyst leads to the formation of hydroalkynation products, the use of phosphinous acid–phosphinito-containing palladium complexes gives rise to formal [2+1] cycloadducts. An experimental and computational approach was employed to study the mechanisms of the palladium-promoted hydroalkynation and [2+1] cycloaddition. On the one hand, experiments highlight the crucial role of acidolysis steps on the catalytic activities. On theother hand, DFT calculations demonstrate the specificity of the phosphinito–phosphinous acid ligands, that is, the non-equivalence of the two phosphorus atoms but the interchangeability of their properties. These results may have important implications for the mechanism of other palladium-catalyzed transfor- mations especially those involving phosphapalladacycles and phosphinous acid–phosphinito-containing palladium complexes
01 May 2015
TL;DR: In this article, an isolated chiral Rh(nbd)(l-proline) as catalyst was used for helix-sense-selective polymerization of DoDHPA.
Abstract: The Rh(nbd)(l-proline) (nbd = 2,5-norbornadiene) catalyst was synthesised with l-proline as ligand. The achiral monomer phenylacetylene, having two hydroxyl groups and a dodecyl group (DoDHPA), was polymerised for the first time using an isolated chiral Rh(nbd)(l-proline) as catalyst to afford polymers of Mr of 28.5 × 104 and 36.2 × 104. The resulting polymers exhibited the Cotton effect at wavelengths assignable to the main chain, indicating that the polymers adopted one-handed helical conformation. These findings suggest that the rhodium complex with chiral amine may be the true active species for helix-sense-selective polymerisation (HSSP) of DoDHPA.
TL;DR: In this article, the electron spin resonance (ESR) was used to determine the structural properties of poly(nisobutyl-3-carbazolylacetylene) radicals.
TL;DR: In this paper, the oligophosphanylamine ligand 1,1,4,7,10,10-hexakis(diphenylphosphanyl)triethylenetetramine (1) was obtained from the reaction of triethyleneetetramerine with six equivalents of chlorodiphenylonphosphine in good yield.
Abstract: The oligophosphanylamine ligand 1,1,4,7,10,10-hexakis(diphenylphosphanyl)triethylenetetramine (1) was obtained from the reaction of triethylenetetramine with six equivalents of chlorodiphenylphosphine in good yield. Ligand 1 was treated with three equivalents of [Cr(CO)4(MeCN)2], [Mo(CO)4(nbd)] (nbd = norbornadiene), or [W(CO)4(MeCN)2] in toluene to give the trinuclear tetracarbonyl complexes [{M(CO)4}3{(PPh2)2N(CH2)2NPPh2(CH2)2NPPh2(CH2)2N(PPh2)2}-κ6P1,P2,P3,P4,P5,P6] [M = Cr (2), Mo (3), W (4)]. Compounds 1–4 were fully characterized by NMR (1H, 13C, 31P) and IR spectroscopy, elemental analysis and crystal structure determination (1–3). The molecular structures of 2 and 3 show the formation of tris-chelate complexes with two M–P–N–P four-membered rings and one M–P–N–CH2–CH2–N–P seven-membered ring.
Patent•
01 Jul 2015
TL;DR: Achiral phenylacetylene having a bulky tbutyl group was synthesized and polymerized by a chiral catalytic system containing [Rh(nbd)Cl]2 (nbd: norbornadiene) and chiral amines to yield a o...
Abstract: A novel achiral phenylacetylene having a bulky t-butyl group was synthesized and polymerized by a chiral catalytic system containing [Rh(nbd)Cl]2 (nbd: norbornadiene) and chiral amines to yield a o...
TL;DR: In this article, a 5.5-exo-Selective reductive Mizoroki-Heck reaction of 4-tert-butyl-1-chlorobenzene with 2,5-norbornadiene has been achieved by [PdCl2(PCy3)2]/HCO2Na to give 5.
Abstract: 5-exo-Selective reductive Mizoroki–Heck reaction of 4-tert-butyl-1-chlorobenzene with 2,5-norbornadiene has been achieved by [PdCl2(PCy3)2]/HCO2Na to give 5-exo-(4-tert-butylphenyl)-2-norbornene in...