Nickel complexes poly

T. Yamamoto, A. Morita, Y. Miyazaki, T. Marayama, H. Wakayama, Z.H. Zhou, Y. Nakamura, T. Kanbara, S. Sasaki, and K. Kubota, Preparation of ir-conjugated poly(thiophene-2,5-diyl), poly(p-phenylene), and related polymers using zerovalent nickel complexes. Linear structure and properties of the TT-conjugated polymers, Macromolecules, 25 1214—1223, 1992. 

As has been noted (29, 31), nickel(III) poly(pyridine) complexes may be prepared. Electron-exchange rates have been determined (15) from a series of cross-reactions. The rate of the electron transfer reaction has... 

Nickel complexes are of considerable importance as stabilizers and antioxidants for polymers of various kinds. The nickel(II) complex of the benzoic acid derivative (12) (see Section 66.4) acts as a stabilizer against oxidation of polybutadiene,46 but is less effective in this respect than the manganese and cobalt complexes. Complex (20) is effective in decreasing the rate of photooxidation of two-phase poly(vinyl chloride)-polybutadiene rubbers 74... 

The copper-catalysed, Ullman-type coupling of aryl, heteroaryl and alkenyl halides may be achieved at ambient temperature using copper(I) thiophene-2-carboxylate as catalyst.60 A new semiconducting poly(anthraquinone-l,5-diyl) with nitro groups at the 4- and 8-positions has been prepared by Ullman-type coupling using metallic copper or a zerovalent nickel complex as catalyst.61... 

The remaining polymerization route involves zero-valent nickel complexes and dihalide monomers. Variations of this route most often arise where different sources or regeneration methods of the active nickel species are utilized [82,199, 200-204]. A typical example is shown below in Scheme 51 in which poly(3-phe-nylthiophene) 50 is synthesized from the parent 2,5-dichlorothiophene. As with the Ullmann reaction, polymerization appears to be most compatible with ring systems containing electron-withdrawing substituents. 

The reaction of Grignard reagents with 1,2-diisocyanobenzenes results in formation of quinox-aline oligomers up to the hexaoligomer. Reactions of 5,8-dibromo-2,3-diphenylquinoxaline with a zero-valent nickel complex afford poly(2,3-diphenylquinoxaline-5,8-diyl). Chemical and electrochemical dehalogenation polycondensations of 2,6-dibromoquinoxaline using nickel complexes afford poly(quinoxaline-2,6-diyl). ... 

The next attempt at these reactions were carried out by Yamamoto et al. [26], They coupled 2,7-dibromo-9,10-dihydrophenanthrene to give an ethano-bridged poly(p-phenylene) derivative [poly(9,10-dihydrophenanthrene-2,7-diyl)] (9) by way of low-valent nickel complexes, which were used either stoichiometrically as reagent (Ni(COD)2) or were generated electrochemically in the reaction mixture. As a result of the insufficient solubilization of the ethano substituents only the oligomer fraction with Mn<1000 is soluble, the polymeric products precipitating out as an insoluble powder. The value of for the soluble fraction of 9 is about 360 nm. 

The reaction involves the amine-catalyzed conversion of an aldehyde into a nitroalkene by reaction with nitromethane followed by a transition-metal-catalyzed Michael addition of p-dicarbonyl compounds in the same reaction vessel. Typically, amine catalysts and nickel complexes are incompatible due to their tendency to chelate and to render each other inactive. However, microencapsulation of poly(ethyleneimine) (PEI) forms catalyst 140, which can successfully be used in tandem with the nickel-based catalyst 141 (Figure 3.6). 

Czv-Symmetric Catalysts. Syndiotactic polymers have been formed using metallocene catalysts where the polymer chain end controls the syndiospecificity of olefin insertion. Resconi has shown that Cp 2MCl2 (M = Zr. Hf) derived catalysts produce predominantly syndiotactic poly(l-butene) with an approximate 2 kcal/mol preference for syndiotactic versus isotactic dyad formation." At —20 °C. Cp 2HfCl2/MAO produces poly(l-butene) with 77% rr triads. Pellecchia had reported that the diimine-ligated nickel complex 30 forms moderately syndiotactic polypropylene at —78 °C when activated with MAO ([rr] = 0.80)." " Olefin insertion was shown to proceed by a 1.2-addition mechanism." in contrast to the related iron-based systems which insert propylene with 2.1-regiochemistry. ... 

ICC1063) and di- 318 (02JCS(D)441) azine-coordinated nickel complexes can be prepared from pyridine-containing aldimines of 2,6-diformyl-4-methylphenol. A nickel cationic complex of a 2,6-bis-azomethine derivative contains two coordinated pyridine N-substituents 319 (M = Ni, R = H, R = Me, = MeOH) (96T3521). Zinc chelate 319 (M = Zn, R = R = Me, no L) has a similar structure (02IC6426). Tetranuclear manganese poly-chelate contains two coordinated pyridine... 

Twieg and coworkers, reported preparation of poly(norbomene) copolymers functionalized with nonlinear optical chromophore side groups. Use was made of (ri -toluene)Ni(C6F5)2, catalyst in the polymerization of norbomene. The nickel complex used to polymerize the norbomene monomers is tolerant to many functional groups found in nonlinear optical chromophores. On the other hand, nitriles and amines other than trisubstituted amines strongly inhibit the reaction. A copolymer of hexylnorbomene and a norbomene-functionalized Disperse Red I chromophore was scaled up and studied in detail. Initial studies indicate that electric field poling is effective but that relaxation of polar order in the poly(norbomene) is faster than in a comparable methacrylate copolymer. The copolymer can be illustrated as follows ... 

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