Well‐Defined Silica‐Supported Zirconium–Benzyl Cationic Species: Improved Heterogenization of Single‐Site Polymerization Catalysts

Zr(CH 2 Ph) 4 ( 1 ) was grafted onto a recently disclosed hybrid material based on amorphous silica that features unique phenol grafting sites {[(≡SiO) 2 (AlOC 6 H 4 OH)(Et 2 O)] ( H )}. A monopodal tribenzyl surface species, structurally similar to the silica‐supported species previously disclosed [≡SiOZr(CH 2 Ph) 3 ] ( 2 ), was obtained and fully characterized as [(≡SiO) 2 (AlOC 6 H 4 OZr(CH 2 Ph) 3 )(Et 2 O)] ( 3 ). The activation of both these species by B(C 6 F 5 ) 3 proceeded by benzyl abstraction to yield the inner‐sphere ion pairs [≡SiOZr(CH 2 Ph) 2 ] + [(PhCH 2 )B(C 6 F 5 ) 3 ] – ( 4 ) and [(≡SiO) 2 (AlOC 6 H 4 OZr(CH 2 Ph) 2 )(Et 2 O)] + [(PhCH 2 )B(C 6 F 5 ) 3 ] – ( 5 ), respectively. These surface species were fully characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, elemental analyses, and 1 H, 13 C, 11 B, and 19 F solid‐state NMR spectroscopy. These isolated cationic catalysts displayed increased ethylene polymerization activity compared to the neutral species. Most importantly, the heterogenization of the cationic complex with the phenol spacer ( 5 ) led to a fourfold increase in productivity compared to that of the silica counterpart 4 , in agreement with reduced surface interactions and improved electrophilicity.