Preparation of isospecific metallocene catalysts for olefin polymerization that are covalently tethered on solid surface

Abstract

Novel methodology was developed for preparation of isospecific metallocene catalysts for olefin polymerization that are tethered on silica surfaces with covalent bonds. A racemic -zirconocene complex that has a Si-Cl moiety on its bridge was immobilized on SiO 2 by the reaction of the Si-Cl anchor with Si-OH on the solid surface. The prepared solid catalyst was found to be effective for isospecific propene polymerization (catalyst ). Pretreatment of silica surfaces with Me 3 SiCl improved the catalyst performance (catalyst ). An -zirconocene complex with a BH group reacted with "vinyl-coated" silica gel to afford another immobilized catalysts (catalyst ). This catalyst achieved satisfactorily high catalytic activity and high isotacticity in its produced polypropene.

New alkenyl-substituted group 4 C-ansa-metallocene complexes. Reactivity of the substituent at the carbon ansa bridge

“…13 C{ 1 H} NMR (125 MHz, C 6 D 6 , 25°C) d: 11.3, 11.6, 12.4, 13.9 (C 5 Me 4 ), 27.9 (9-BBNCH 2 ), 33.1 (CH 2 CH 2 CH 2 ), 34.2 (CH 2 CH 2 CH 2 ), 39.1 (CH), 23.2,33.2,104.3,107.2,119.7,121.9,128.9 (C 5 H 4 ),104.5 114.8,117.6,120.3,129.9 (C 5 Me 4 : 11.3, 11.4, 11.6, 11.6, 12.3, 12.4, 14.3, 14.5 (C 5 Me 4 ), 33.4, 34.1 (CH 2 CH(CH 3 )CH 2 ), 23.0, 23.2, 23.6, 23.7,25.7,28.7,31.7,31.9 (CH 2 ,22.6,22.9 (CH 3 ), 23.5, 25.6 (CH 2 CH(CH 3 )CH 2 ), 37.4, 37.7 (CH), 41.6, 41.9 (CH 2 CH(CH 3 )CH 2 ), 104. 7,104.9,115.0,115.2,116.8,117.7,120.2,120.3,128.8,130.0 (C 5 H 4 ),104.5,104.6,107.2,107.4,118.7,119.6,122.1,122.2,128.9,130.0 (C 5 Me 4 (21) To a solution of 2 (0.30 g, 0.84 mmol) in toluene (50 mL) was added dropwise HSiMe 2 Cl (0.12 g, 1.26 mmol) in toluene (25 mL). To this solution was added three drops of the Karstedt catalyst [platinum(0) divinyltetramethylsiloxane in xylene (3-3.5%)] and the mixture was stirred for 15 h at room temperature.…”

“…One route for the immobilisation of metallocene complexes is the reactivity of a C@C bond of an alkenyl substituent on the cyclopentadienido ring or at the ansabridged atom [6]. Several studies have been carried out in which hydrosilylation of the ansa-zirconocene complexes with vinyl or allyl groups in the silicon bridge is followed by supporting the system on silica [7], modified silica surfaces [3a] or organosilicon dendrimers [8]. In other cases, the initial modification by hydrosilylation of ansa-cyclopentadienyl ligands is followed by their incorporation in group 4 metallocene systems [9].…”

“…Zr(1)-C (19) 2.326(3) Zr(1)-C(26) 2.297(3) Zr(1)-Ct(1) 2.507(3) Zr(1)-Ct (2) 2.523(3) C(1)-C(6) 1.529(4) C(6)-C (7) 1.531(4) C(6)-C (16) 1.509(4) C(16)-C (17) 1.497(4) C(17)-C (18) 1.300 (4) C(26)-Zr(1)-C (19) 103.6(1) Ct(1)-Zr(1)-Ct (2) 116.7(3) C(1)-C(6)-C (16) 115.6(2) C(7)-C(6)-C (16) 117.3(2) C(1)-C(6)-C (7) 101.1(2) C(6)-C(16)-C (17) 113.2(2) C(16)-C(17)-C (18) 125 . Ct (1) is the centroid of the Cp ring and Ct (2) is the centroid of the Cp * ring. Molecular structure and atom labelling scheme for [Zr{(CH 2 @CHCH 2 )CH(g 5 -C 5 Me 4 )(g 5 -C 5 H 4 )}(CH 2 Ph) 2 ] (11) with thermal ellipsoids at the 30% probability.…”

Silica-nanosphere-based organic–inorganic hybrid nanomaterials: synthesis, functionalization and applications in catalysis

“…10 In order to surmount the problems associated with both types of catalytic systems, heterogenisation is usually performed, either through entrapment or covalent grafting of the active catalytic species on surfaces or inside the pores of a solid support, such as magnetite, graphene, silica, alumina, zeolite, ceria and so forth. [11][12][13][14][15][16] Covalent binding is considered to be the best technique, because the catalyst becomes sufficiently robust to survive the harsh reaction conditions and simultaneously minimizes the leaching phenomenon, which allows the catalyst to be reused many times. 17 Several attempts have been made to make all catalytically active molecules on solid supports accessible to reactants, so that an activity similar to the homogeneous catalyst could be achieved.…”

Silica nanospheres supported diazafluorene iron complex: an efficient and versatile nanocatalyst for the synthesis of propargylamines from terminal alkynes, dihalomethane and amines

“…Over the past few decades, there have been extensive reports on the heterogenization of soluble catalysts using various solid support materials such as metal oxides, polymers and nanocomposites. [14][15][16][17][18][19] In this context, nanomaterials as a solid support have conquered new horizons in the eld of catalysis due to their intriguing properties such as large surface area, excellent stability and high complex loading in comparison to bulk materials. It is well evident from literature that the novel heterogenized catalysts are based on silica nanospheres as a solid support, primarily because they display some advantageous properties, such as nanometre size, excellent chemical and thermal stability, good accessibility, porosity, and large surface area to volume ratio.…”