Butadiene Polymerization Catalyzed by Lanthanide Metallocene−Alkylaluminum Complexes with Cocatalysts:  Metal-Dependent Control of 1,4-Cis/Trans Stereoselectivity and Molecular Weight

Abstract

A series of bimetallic complexes composed of lanthanide metallocene and trimethylaluminum, Cp*2Ln[(μ-Me)AlMe2(μ-Me)]2LnCp*2 (Cp* = η5-C5Me5, Ln = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Tm, Yb, Lu), were prepared, and the ability to catalyze polymerization of butadiene in the presence of cocatalysts, AlR3 (R = Me, i Bu) and [Ph3C][B(C6F5)4], was studied as a function of the 11 different lanthanide metal species and the kind of alkylaluminum in the cocatalyst. Both catalytic activity and microstructure of polybutadiene depended strongly on the kind of lanthanide metal and the trialkylaluminum. The Gd complex in combination with Al i Bu3/[Ph3C][B(C6F5)4] was extremely active and gave perfectly 1,4-cis regulated polybutadiene at −40 °C. In contrast, the Ce complex with almost similar cocatalysts, AlMe3/[Ph3C][B(C6F5)4], yielded polybutadiene having a very high content of 1,4-trans microstructure (1,4-trans selectivity = 93.8%). With the Al/Ln ratio was 3−5, the polymerization systems, in which the alkylaluminum worked as an activator, showed somewhat living-like nature; the M n of the resulting polybutadiene increased in proportion to monomer consumption, while the molecular weight distribution stayed narrow throughout the reactions. In the presence of a large amount of monomer, molecular weight of polybutadiene was conveniently controlled by additional excess alkylaluminum, which functioned as a chain transfer agent.

Highly active and stereospecific polymerizations of 1,3-butadiene by using bis(benzimidazolyl)amine ligands derived Co(II) complexes in combination with ethylaluminum sesquichloride

“…Recently there are a number of reports derived from such organometallic complexes for BD polymerization which are proved to be highly stereospecific coupled with good activity [2,5]. Another emerging class of catalysts is lanthanocenes that produce PBD with exclusively cis to predominately trans forms depending on the structure of the lanthanides used [6,7].…”

Precisely Controlled Polymerization of Styrene and Conjugated Dienes by Group 3 Single‐Site Catalysts

“…Moreover, this system showed good activities and narrow molecular weight distributions even at low temperature (−78 °C ). Then the same group synthesized a series of lanthanide complexes Cp′ 2 Ln[( μ ‐Me)AlMe 2 ( μ ‐Me) 2 ]LnCp′ 2 (Cp′= η 5 ‐C 5 Me 5 , Ln=Nd, Sm, Gd, Ce, Tb, Dy, Ho, Tm, Yb, Lu), and systematically investigated their catalytic performances toward BD polymerization . Both catalytic activities and microstructures of the resultant polymers were highly dependent on the types of the central metal and AlR 3 , as showed in Table .…”

Organolanthanide Complexes Supported by Thiazole-Containing Amidopyridinate Ligands: Synthesis, Characterization, and Catalytic Activity in Isoprene Polymerization

“…i Pr,H 19,20,21,22 ), 1.55 (s, 6H, CMe 2 H 23,24 ), 3.79 (sept, 3 J HH = 6.9 Hz, 2H, CH i Pr, H 17,18 ), together 4H,CH,H 2,3,4,25,26 ),together 5H,CH,H 9,10,11,16,25,26,27 ,24 ), 43.4 (s, LuCH 2 ), 66.3 (s, C(CH 3 ) 2 , C 6 ), 118.9 (s, CH, C 2,4 ), 121.7 (s, C 16,27 ), 122.3 (s, CH, C2,4), 123.6 (s, CH, C 9,11 ), 123.7 (s, CH, C 10 ), 124.7 (s, C 16,27 ), 127.6 (s, C 25,26 ), 128.2 (s, C25,26) 133.2 (s, C15), 139.6 (s, CH, C3), 146.6 (s, C13), 147.1 (s, C 7 ), 148.5 (s, C 8,12 ), 150.6 (s, C 14 ), 170.2 (s, C 5 ), 179.6 (s, C 1 ) ppm.…”