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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: The insertion of olefins into the Pt-H bond of trans-PtH(NO3)(PEt3)2 occurs via preliminary substitution of nitrate by olefin, and the intermediate trans-[PtC2H4]-BPh4 has been isolated as mentioned in this paper.
Abstract: The insertion of olefins into the Pt–H bond of trans-PtH(NO3)(PEt3)2 occurs via preliminary substitution of nitrate by olefin, and the intermediate trans-[PtH(C2H4)(PEt3)2]BPh4 has been isolated. Butadiene and allene give π-allylic complexes and cyclo-octa-1,5-diene and norbornadiene give enyl-systems. Whereas PhN:CH·CH:CHPh gives [PtH(PhN:CH·CH:CHPh)(PEt3)2]BPh4 with no insertion, CH2:CHCOMe gives [Pt(CH2·CH2·-COMe)(PEt3)2]BPh4, the Pt–C σ-bond of which is readily hydrolysed to give [Pt2(OH)2(PEt3)4]2+ and ethyl methyl ketone.
20 citations
TL;DR: The variable-temperature IR spectra of (η 4 -norbornadiene)Fe(CO) 3 and related complexes reveal a coalescence phenomenon involving the CO stretching vibrational bands as discussed by the authors.
20 citations
TL;DR: In this paper, the microstructure of polynorbornadiene (PNBD) was investigated by high-resolution 1H and 13C NMR spectroscopy.
Abstract: The polymerization of norbornadiene (NBD) initiated by the 2-chloro-2,4,4-trimethylpentane/titanium tetrachloride system was investigated. Efforts were made to develop conditions for the living polymerization of NBD by the use of proton trap and electron donor in the −35 to −60 °C range however this objective was only partially attained. The molecular weights increased linearly with conversion, and the rate was first-order in confirmed monomer concentration up to approximately 25%; however, chain transfer became operational beyond this range. The microstructure of polynorbornadiene (PNBD) was investigated by high-resolution 1H and 13C NMR spectroscopy. According to these techniques, the chain consisted of about equal amounts of exo/exo and exo/endo connected tricyclic repeat units. The head and tail groups were identified and quantitated, and this led to absolute molecular weight determination by integration. Molecular weights obtained by this method and by gel permeation chromatography (relative to polyisobutylene standards) were in good agreement. NMR spectroscopy indicated the presence of small but still identifiable amounts of branching units and their structures. The plot of the glass-transition temperature against the reciprocal of the number-average molecular weight was linear and yielded a glass-transition temperature of 323 °C for the infinite molecular weight polymer. According to thermogravimetric analysis, PNBD was stable up to approximately 250 °C and showed a 5% weight loss at approximately 335 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 732–739, 2003
20 citations
TL;DR: Variable temperature (1)H NMR experiments show that the [Ni(diene)] fragments are freely rotating even at 193 K.
Abstract: The nickelacarboranes [NEt(4)][2-(eta(3)-C(3)H(4)R)-closo-2,1,7-NiC(2)B(9)H(11)] (R = H (1a), Ph (1b)) have been synthesized via reaction between [Na](2)[nido-7,9-C(2)B(9)H(11)] and [Ni(2)(micro-Br)(2)(eta(3)-C(3)H(4)R)(2)] in THF (THF = tetrahydrofuran), followed by addition of [NEt(4)]Cl. Protonation of 1a in the presence of a donor ligand L affords the complexes [2,2-L(2)-closo-2,1,7-NiC(2)B(9)H(11)] (L = CO (2), CNBu(t) (3)). Addition of PEt(3) (1 equiv) to 2 produces quantitative conversion to [2-CO-2-PEt(3)-closo-2,1,7-NiC(2)B(9)H(11)], 4. Species 2-4 exhibit in solution hindered rotation of the NiL(2) fragment with respect to the eta(5)-C(2)B(9) cage unit. Protonation of 1a in the presence of a diene affords the neutral complexes [2-(eta(2):eta(2)-diene)-closo-2,1,7-NiC(2)B(9)H(11)] (diene = C(5)Me(5)H (5), dcp (6), cod (7), nbd (8), chd (9), and cot (10a); dcp = dicyclopentadiene, cod = 1,5-cyclooctadiene, nbd = norbornadiene, chd = 1,3-cyclohexadiene, and cot = cyclooctatetraene). Variable temperature (1)H NMR experiments show that the [Ni(diene)] fragments are freely rotating even at 193 K. A small quantity of the di-cage species [2,2'-micro-(1,2:5,6-eta-3,4:7,8-eta-cot)-(closo-2,1,7-NiC(2)B(9)H(11))(2)] (10b) is formed as a coproduct in the synthesis of 10a. This species can be rationally synthesized by protonation of 1a and subsequent addition of 10a.
20 citations
TL;DR: periodic DFT and electronic structure analyses revealed weak C−H→Co σ‐interactions, augmented by dispersive stabilization between the alkane ligand and the anion microenvironment, consistent with a η1:η1‐alkane binding mode.
Abstract: The synthesis, and x-ray structure, of a cobalt s -alkane complex, [Co(Cy 2 P(CH 2 ) 4 PCy 2 )( norbornane )][BAr F 4 ], is achieved by a single-crystal to single-crystal solid/gas hydrogenation from a norbornadiene precursor. Magnetic data show this complex to be a triplet. Periodic DFT and electronic structure analyses identify weak C-H ··· Co σ -interactions, augmented by dispersive stabilisation between the alkane ligand and the anion-microenvironment. The calculations are most consistent with a η 1 : η 1 -alkane binding mode.
20 citations