Preparation of Phosphine-Amido Hafnium and Zirconium Complexes for Olefin Polymerization

Abstract

Aniline (N-R-C 6 H 5 NH) and 1,2,3,4-tetrahydroquinoline (2-R-C 9 H 9 NH) derivatives were ortho-lithiated via conversion of the respective −NH groups to −N(COOLi), followed by treatment with tBuLi. The resulting ortho-lithiated compounds were transformed to ortho-Ph 2 P-substituted derivatives on treatment with Ph 2 P(OPh). Further reaction of the resulting compounds with M(CH 2 Ph) 4 (M = Zr, Hf) afforded a series of Hf and Zr complexes: (2-R-8-Ph 2 PC 9 H 9 N)Hf(CH 2 Ph) 3

Preparation of Pyridylamido Hafnium Complexes for Coordinative Chain Transfer Polymerization

“…It shows advantageous performance in ethylene and α-olefin (co)polymerization reactions, though its activation reaction is rather tricky [5][6][7]. In ethylene/α-olefin copolymerization reactions, it is capable of incorporating a large amount of α-olefins (uniquely among Hf catalysts) [8,9]. α-Olefin content in the copolymer generated with I is comparable with that in the copolymer generated with a constrained geometry complex, [Me 2 Si(η 5 -C 5 Me 4 )NtBu]TiMe 2 , though its activity is significantly lower than that of the constrained geometry complex (~1/ 15 ).…”

Preparation of [bis(amido)-phosphine] and [amido-phosphine sulfide or oxide] hafnium and zirconium complexes for olefin polymerization

“…Stimulated by these reports, we prepared phosphine oxide as well as phosphine sulfide ligands from the phosphine-amido ligands that were used in the construction of 1 and 2 (Scheme 1). The phosphine-amido ligands were straightforwardly prepared from tetrahydroquinoline or secondary aniline derivatives by a one-pot procedure [19]. The key of this simple protocol was ortho-lithiation directed by in situ generated lithium carbamate.…”

“…Benzyl complexes 11e18 were activated with methylcyclohexane-soluble [HNMe(C 18 H 37 ) 2 ] þ [B(C 6 F 5 ) 4 ] À (1.2 equiv) using MAO (Al/M ¼ 125) as a scavenger [15,19]. Though the pentacoordinated [N,N,C]HfX 2 -type complexes constructed from the pyridine-amido ligand and by incorporating ortho-metalated aryl moieties have been extensively studied because of their good polymerization activity [35e40], the [N,P,N]M(CH 2 Ph) 2 -type complexes (M ¼ Hf and Zr, 15e18) developed herein exhibited negligible activity.…”

“…This simple protocol allowed for the construction of various LM(CH 2 Ph) 3 -type complexes with diverse spectator ligands L (L ¼ imine-amido, imine-enamido, or aminotroponiminato) [11e16] and LM(CH 2 Ph) 2 -type complexes with ortho-metalated aryl moieties [17,18]. Recently, we reported LM(CH 2 Ph) 3 -type complexes with phosphine-amido spectator ligands (1 and 2), which exhibited good catalytic performance in ethylene/1-octene copolymerization [19]. Phosphine and its related ligands have been actively utilized in the construction of group 4 and group 5 metal complexes for catalysis [20e26].…”

Preparation of “Constrained Geometry” Titanium Complexes of [1,2]Azasilinane Framework for Ethylene/1-Octene Copolymerization

“…Since the discovery of homogeneous metallocene catalysts (single-site polyolefin catalysts) in the 1970s by Kaminsky, their industrial impact has escalated, with current annual production of more than five million tons of polyolefins [ 1 , 2 , 3 ]. The initially developed family of metallocene-type catalytic species has expanded to include half-metallocenes constructed with a cyclopentadienyl (Cp) and an amido ligand [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ], and further to post-metallocenes (or non-metallocenes) comprising non-cyclopentadienyl ligands [ 11 , 12 , 13 , 14 , 15 , 16 ]. Among the homogeneous Ziegler catalysts, Me 2 Si-bridged ansa -Cp/amido half-metallocenes, a typical example of which is [Me 2 Si(η 5 -Me 4 C 5 )(N t Bu)]TiCl 2 , are termed “constrained-geometry catalysts (CGCs, Chart 1 )”, and have drawn significant attention from both industry and academia.…”