Diethylbis(dipyridyl)cobalt. A butadiene dimerization catalyst

Diethylbis(2,2′-bipyridine)iron/MAO. A Very Active and Stereospecific Catalyst for 1,3-Diene Polymerization

“…Polymers with a 1,2 or 3,4 structure are formed from butadiene, isoprene, (E)-1,3-pentadiene and 3-methyl-1,3-pentadiene, while cis-1,4 polymers are derived from 2,3-dimethyl-1,3-butadiene. The 1,2 (3,4) polymers obtained at 25 8C are amorphous, while those obtained below 0 8C are crystalline, as was determined by means of X-ray diffraction. Mechanistic implications of the results are briefly discussed.…”

“…Diethylbis(2,29-bipyridine)Fe and diethylbis(2,29-bipyridine)Co were prepared according to the literature. [2,3] MAO (Witco, 10 wt.-% solution in toluene) was used as received. Toluene (Baker, A99.5%) was dried by refluxing Communication: Diethylbis(2,29-bipyridine)Fe/MAO is an extremely active catalyst for the polymerization of 1,3-dienes.…”

“…It is well known [9 -13] that formation of a cis-1,4 versus a 1,2 unit depends on whether the new monomer reacts at C1 or C3 of the allyl group. In the active species of (Bipy) 2 FeEt 2 / MAO the coordination geometry around Fe is such that butadiene (isoprene) reacts preferentially at C3 of the allyl group to give 1,2 (3,4) units. However, in the allyl group derived from DMB a Me group is bound to C3.…”

Insertion chemistry into metal–carbon bonds

“…63 Before my move to Waseda, we observed that employment of the PMe 3 helps to stabilize the CO-inserted acylpalladium complexes and CO insertion into the allylpalladium bond can be accomplished under appropriate conditions [eqn. (10)]. 64 Our later studies at Waseda revealed that the CO insertion process can take place under various conditions and that the CO insertion reaction into 11 proceeded even in the presence of a small amount of a secondary amine to give the acylpalladium complex 12 [eqn.…”