Beyond the Active Site. Cp*ZrMe3/Sulfated Alumina‐Catalyzed Olefin Polymerization Tacticity via Catalyst⋅⋅⋅Surface Ion‐Pairing. Issue 11 (22nd April 2021)

• Record Type: Journal Article
• Authors: Zhang, Jialong; Mason, Alexander H.; Wang, Yang; Motta, Alessandro; Kobayashi, Takeshi; Pruski, Marek; Gao, Yanshan; Marks, Tobin J.
• Is Part Of: ChemCatChem. Volume 13:Issue 11(2021)
• Page Start: 2564
• Page End: 2569
• Publication Date: 2021-04-22
• Subjects: Zirconocene -- olefin polymerization -- isotactic polypropylene -- surface organometallics -- solid-state NMR; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.202100406
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: Surface‐bound organometallic molecules have recently enabled the development of single‐site heterogeneous catalysts, advancing the atomic scale understanding and diversity of heterogeneous catalysis. Here we report that supporting Cp*ZrMe3 (Cat1 ) on acidic sulfated‐alumina (AlS) affords the surface catalyst Cat1/AlS, which was characterized by multi‐dimensional solid‐state NMR spectroscopies, and is active in ethylene homo‐ and copolymerizations, as well as propylene and 1‐hexene homopolymerizations. In contrast to propylene (or 1‐hexene) polymerization by homogeneous Cp*ZrMe2 + B(C6 F5 )4 − which yields atactic polyolefins, Cat1/AlS promotes remarkable isotacticity with mmmm >95 %. Complementary DFT analysis argues that the restrictive local Cat1/AlS C 1 ‐symmetry favors activation and enchainment at the propylene re enantioface, promoting isotactic polymerization via a "back‐skip‐like" mechanism. Abstract : Beyond the active site : Surface‐bound organometallic molecules can enable the rational design, synthesis, and diversification of single‐site heterogeneous catalysts. Here we report that adsorbing Cp*ZrMe3 on sulfated‐alumina creates a surface entity which catalyzes propylene or 1‐hexene polymerization with high isotacticity via imposed surface environmental C1 ‐ symmetry. In contrast, the homogeneous analogue produces only atactic polymer.