Butadiene reactions with metal atoms

Butadiene)zirconocene reacts with metal carbonyls in a similar way as with ketones. Carbon-carbon coupling between a butadiene terminus and the carbonyl carbon atom occurs readily to yield a metallacyclic product, only that generally a metallacyclic n-allyl metallocene system is obtained from the reactions with metal carbonyls.8 Sometimes, O-zirconated Fischer-type carbene complexes are readily formed in this way that cannot be easily obtained by other routes. A typical example is the... 

The essential steps in the nickel-catalyzed 1 1 codimerization reaction, which involve hydride addition to butadiene and ethylene coordination to the metal atom, were first proposed by Kealy, Miller, and Barney (35) and were later demonstrated by Tolman (40) using a model complex. Tolman prepared the complex H—Ni+L PFe [L = (EtO)3P] and showed that, after prior dissociation to form H—NiL3, it can react with butadiene to form a 7r-crotyl complex 19. 

Interaction of Metal Atoms and Dienes Reaction of W Atoms with 1,3-Butadiene [546]... 

The reactions of butadiene, C4H6, with certain metal compounds are particularly interesting because bridged complexes are produced. This can occur because butadiene has two double bonds that can function simultaneously as electron pair donors to two metal atoms. When the reaction is carried out using CuCl and liquid butadiene at -10 °C, it can be represented by the following equation ... 

This catalyst [111] gives several polymer molecules per titanium atom, and there are similar findings for Cr(acac)3/AlEt3 for butadiene and Cr(acac)3/AlEt2 Cl or AlEtCl2 for ethylene [139]. It appears reasonable to assume, therefore, that all the transition metal participates in the reaction. With Cr(acac)3/AlEt2Cl the average number of polymer molecules approximates to one per Cr atom which additionally would indicate the absence of a transfer reaction. This point needs to be confirmed, however, with separate measurements of active centre concentrations and chain transfer, since two soluble nickel catalysts [68, 124] have been reported to have low catalyst efficiencies. 

Although presently lacking industrial importance, alternating copolymers can be made from propylene and butadiene, also from propylene and isoprene. Copolymers of propylene and butadiene form with vanadium- or titanium-based catalysts combined with aluminum. alkyls. The catalysts have to be prepared at very low temperature (-70 C). Also, it was found that a presence of halogen atoms in the catalyst is essential.Carbonyl compounds, such as ketones, esters, and others, are very effective additives. A reaction mechanism based on alternating coordination of propylene and butadiene with the transition metal was proposed by Furukawa. ... 

The thermal reaction of cis or trans 1,4-poly(butadiene) with iron carbonyls results in geometrical isomerization of the alkenyl moieties and formation of polymers containing conjugated diene) iron tricarbonyl units. In the course of our continuing studies of the formation of stable colloidal iron dispersions by thermal decomposition of metal carbonyls in the presence of functional polymers, some aspects of this work have been repeated. Our objective was to isolate the soluble organometallic polymer which was intermediate to particle nucleation and independently examine the intramolecular condensation of metal atoms to yield metal clusters and metal particles. In this paper, the structure of the intermediate obtained on thermolysis of an excess of FeCCO) in a dilute xylene solution of c/5-poly(butadiene) has been described. 

Carbon-sulfur bond breaking was observed while treating thiophene with Cp"Co(C2H4)2 at 70 °C in benzene. A cobalt metal center had inserted into the C-S bond and a second Cp Co unit had complexed to the cobalt, sulfur, and C-C double bond 330. Further reaction of the resulting compound with H2S produced a new butadiene dithiolate compound, in which a sulfur atom has been inserted into the metal-carbon bond 331. Reaction with dibenzothiophene produced an analogous dinuclear C-S insertion-reaction adduct (Equation (54)). ... 

Sketch (a) the transition state for a concerted metal atom-assisted 3,9 hydride shift (b) two PNP ligands (c) the ligand used for selective dimerization of butadiene (d) a general structure for molybdenum- and tungsten-based metathesis precatalyst (e) a six-coordinate rathenium precatalyst for metathesis (f) a solid isolated from the reaction between Pd(OAc)j plus PRj (R = o-tolyl) (g) a T-shaped palladium complex and a two-coordinate palladium complex with a monodentate phosphine (h) an iron complex with a seven-membered metallacycle (i) the transition state for metal-catalyzed cyclopropanation (j) a rhodium and a copper precatalyst used in cyclopropanation reactions. 

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