Norbornadiene

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

Ring-opening metathesis polymerization of norbornene and norbornadiene by tungsten(II) and molybdenum(II) complexes

Abstract: The reaction of norbornene (NBE) and norbornadiene (NBD) in the presence of seven-coordinate tungsten(II) and molybdenum(II) complexes of the [(CO) 4 M(μ-Cl) 3 M(SnCl 3 )(CO) 3 ] and [MCl(M′Cl 3 )(CO) 3 (NCMe) 2 ] (M=W, Mo; M′=Sn, Ge) types leads to ring-opening metathesis polymerization (ROMP) and to the formation of high molecular weight polymers The geometric structure of these polymers was determined by means of 1 H - and 13 C -NMR spectroscopy The monitoring of the reaction between cyclic olefins and the metal complex by means of 1 H -NMR spectroscopy allowed us to observe the coordination of NBD to metal atoms in the initiation step of the polymerization process Compounds of the [MCl(SnCl 3 )(CO) 3 (η 4 -NBD)] type prepared directly from [(CO) 4 M(μ-Cl) 3 M(SnCl 3 )(CO) 3 ] or [MCl(M′Cl 3 )(CO) 3 (NCMe) 2 ] (M=W, Mo) in the presence of an excess of NBD initiate the ROMP reaction immediately The detection of the first-formed products in the reaction between the metal complex and cyclic olefins provides valuable information concerning the nature of the initiating species

Electronic synergism in [RuCl2(PPh3)2(amine)] complexes differing the reactivity for ROMP of norbornene and norbornadiene

Abstract: The reactivity of the new complex [RuCl2(PPh3)2(3,5-Me2piperidine)], complex 1, was investigated for ring opening metathesis polymerization (ROMP) of norbornene (NBE) and norbornadiene (NBD) in the presence of ethyl diazoacetate (EDA) in CHCl3. The aim is to observe the combination of PPh3 and an amine as ancillary ligands concerning the steric hindrance and the electronic perturbation in the properties of the N-bound site when replacing the amines. Thus, the results with 1 were compared to the results obtained when the amine is piperidine (complex 2). Reaction with 1 provides 70% yield of isolated polyNBE (Mn = 8.3 × 104 g/mol; PDI = 2.03), whereas 2 provides quantitative reaction (Mn = 1.2 × 105 g/mol; PDI = 1.90) with [NBE]/[Ru] = 5000, [EDA]/[Ru] = 48 and 1.1 μmol of Ru for 5 min at 25 °C. The resulting polymers showed c.a. 62% of trans-polyNBE, determined by 1H NMR, and Tg = 32 °C, determined by DSC and DMTA. For ROMP of NBD, 1 showed quantitative yield with PDI = 2.62 when [NBD]/[Ru] = 5000 for 20 min at 25 °C, whereas the reaction with 2 reached 55% with PDI = 2.16 in the same conditions. It is concluded that the presence of the two methyl groups in the piperidine ring provides an increase in the induction period to produce the Ru-carbene species justifying better polyNBE results with 2, and a greater amine ⟶ σ Ru ⟶ π monomer synergism which contributed to the best activation of less tensioned olefin as NBD.

On Transition Metal-Catalyzed Reactions of Norbornadiene and the Concept of π Complex Multicenter Processes

Abstract: Publisher Summary This chapter focuses on bicyclo[22l]heptadiene-2,5 (norbornadiene), a new versatile substrate for catalytic studies The chapter describes its transition metal-catalyzed reactions and discusses the mechanism of these reactions and the function of transition metals in catalytic processes of this kind The chemistry of norbornadiene is characterized by strain and homoconjugation Hence, the olefin undergoes a series of addition reactions that are frequently accompanied by the formation of the nortricyclene system—the direction of electrophilic attack being usually exo Transition metal complexes, such as nickel carbonyl or bisacrylonitrile nickel have been found to greatly promote the reaction of acrylonitrile with norbornadiene Norbornadiene may be carbonylated essentially under the conditions of Reppe's acrylic ester synthesis