Polymerization by transition metal derivatives. XII. Factors controlling activity and stereospecificity in the 1,4 polymerization of butadiene by monometallic nickel catalysts

Abstract

In the course of investigations of polymerization of diolefins by transition metal derivatives, we have synthesized various monometallic nickel coordination catalysts. The complexes were prepared by reacting 2,6,10‐dodecatriene‐1,12‐diyl nickel with protonic acids; they were shown to initiate the stereospecific polymerization of 1,3‐butadiene. The study of these catalysts showed the strong influence of the nature of the counteranion used on the stereospecificity and the polymerization rate. Moreover, by adding various ligands, we were able to modify the behavior of the catalytic systems and to prepare either pure cis‐1,4 or pure trans‐1,4 or cis–trans equibinary polybutadienes, starting from the same complex and keeping a high 1,4 specificity. Some of these modifications were shown to be reversible.

Effects of halogen ligands on 1,3-butadiene polymerization with cobalt dihalides and methylaluminoxane

“…On the other hand, Durand et al [4] have synthesized various monometallic nickel coordination catalysts by reacting 2, 6, 10-dodecatriene-1, 12-diyl nickel with various protonic acids HCl, HBr, HI, CF 3 COOH, CCl 3 COOH, etc., and applied them for 1,3-butadiene polymerization. The results indicated that the nature of the anionic ligand played a significant role in stereospecificity and activity.…”

Copolymerization of 1,3‐butadiene and isoprene with cobalt dichloride/methylaluminoxane in the presence of triphenylphosphine

“…Basically, the mode of monomer insertion strongly depends on the types of transition‐metal complexes. The addition of a Lewis base to a certain catalyst system can also change the microtacticity of the polymer 14–18. Besides this topic, modifications of polymer chains by functionalization and/or copolymerization are being advanced to improve the mechanical properties of polymers for industrial purposes.…”

Effects of tris(pentafluorophenyl)borane on the activation of a metal alkyl‐free Ni‐based catalyst in the polymerization of 1,3‐butadiene

“…As mentioned in the early part of this study, it could be inferred that the catalytic complexes are formed by the reaction of 2,6,10‐dodecatriene‐1,12‐diyl nickel ( 6 ) with B(C 6 F 5 ) 3 (Scheme ). This is in consideration of the fact that the reaction of Ni(COD) 2 with 1,3‐butadiene gave 2,6,10‐dodecatriene‐1,12‐diyl nickel 21, 22. However, the low catalytic activity observed at [B(C 6 F 5 ) 3 ]/[Ni] = 1 seemed to show that the active species was not a definite complex formed by the reaction of one equivalent of 2,6,10‐dodecatriene‐1,12‐diyl nickel with one equivalent of B(C 6 F 5 ) 3 .…”

“…This is in consideration of the fact that the reaction of Ni(COD) 2 with 1,3-butadiene gave 2,6,10dodecatriene-1,12-diyl nickel. 21,22 However, the low catalytic activity observed at [B(C 6 F 5 ) 3 ]/[Ni] ϭ 1 seemed to show that the active species was not a definite complex formed by the reaction of one equivalent of 2,6,10-dodecatriene-1,12-diyl nickel with one equivalent of B(C 6 F 5 ) 3 . Instead, it could rather form by the reaction of an excess amount of B(C 6 F 5 ) 3 with 2,6,10-dodecatriene-1,12-diyl nickel.…”

“…Presumably, the catalytic complexes inducing the polymerization are formed by the reaction of two catalyst ingredients, Ni(COD) 2 and B(C 6 F 5 ) 3 , with 1,3-butadiene. It has been reported 21,22 that the reaction of Ni(COD) 2 with 1,3-butadiene forms 2,6,10-dodecatriene-1,12-diyl nickel, which alone has no catalytic activity for the 1,4-cis polymerization of 1,3-butadiene. Thus, it is conceivable that the catalytic complexes are formed by the reaction of 2,6,10-dodecatriene-1,12-diyl nickel with B(C 6 F 5 ) 3 .…”