Synthesis and structures of dialkyl zirconium complexes with an [OSSO]-type bis(phenolate) ligand bearing a trans-1,2-cyclooctanediylbis(thio) unit

Enantio‐ and Stereoselective Cyclopolymerization of Hexa‐1,5‐diene Catalyzed by Zirconium Complexes Possessing Optically Active Bis(phenolato) Ligands

“…Their specific optical rotations [α] D were −8.9° for the first fraction and +8.9° for the second fraction. According to our previous report,[9a] the corresponding chiral dichloro zirconium(IV) complexes 2 were prepared by the reactions of the dilithium salt of (−)‐ 1 or (+)‐ 1 , prepared by treatment of (−)‐ 1 or (+)‐ 1 with 2 equiv. of BuLi in Et 2 O at 0 °C, with ZrCl 4 at −78 °C (Scheme ).…”

“…Recently, we have reported the development of [OSSO]‐type bis(phenolate)s incorporating with a trans ‐1,2‐cyclooctanediyl platform and the complexation of the pre‐ligand 1 with several early‐transition metal and aluminum complexes; we have found that zirconium(IV) and hafnium(IV) complexes with activator could promote precisely isospecific polymerizations of α‐olefins such as 1‐hexene, 4‐methyl‐1‐pentene, and propylene involving excellent activity . Since our zirconium complexes having the pre‐ligand 1 adopt chiral C 2 ‐symmetric structures with a helical arrangement of the robust [OSSO]‐type ligand around the octahedral metal center even in solution, we considered that the optically active complexes should ensure an enantio‐ and stereoselective cyclopolymerization of non‐conjugated α,ω‐dienes.…”

Highly Active and Isospecific Styrene Polymerization Catalyzed by Zirconium Complexes Bearing Aryl-substituted [OSSO]-Type Bis(phenolate) Ligands

“…Recently, we have succeeded in the development of an [OSSO]-type bis(phenolate) ligand ( 4 ) based on a trans -1,2-cyclooctanediyl platform and the preparation of several early-transition metal and aluminum complexes [ 43 , 44 , 45 , 46 , 47 , 48 ]. We have also found that zirconium(IV) and hafnium(IV) complexes 5 [ 49 , 50 ] and 6 [ 51 ] incorporating ligand 4 with activator could promote precisely isospecific polymerizations of α-olefins such as 1-hexene, 4-methyl-1-pentene, and propylene involving excellent activity ( Scheme 1 ).…”

Neutral Methyl and Cationic Aluminum Complexes Supported by a trans-1,2-Cyclooctanediyl-Bridged [OSSO]-Type Bis(phenolato) Ligand: Synthesis, Structures, and Use in Catalysis for Propylene Oxide Polymerization

“…Beyond the ubiquitous [ONNO]-type ligands, sulfur-linked bis(phenolate) [OSSO]-type ligands have also proven the formation of six-coordinated cationic aluminum species by Okuda . On the other hand, we have recently reported the development of the new [OSSO]-type ligand 1 based on a trans -1,2-cyclooctanediyl platform, along with the synthesis of several group 4 and 5 transition-metal complexes (Scheme ). − Upon activation with B(C 6 F 5 ) 3 or (Ph 3 C)[B(C 6 F 5 ) 4 ], dibenzylzirconium complex 2 achieved high activity up to 2500 g mmol –1 h –1 and complete isospecific polymerization of 1-hexene ([ mmmm ] >95%) . Moreover, the dibenzylhafnium complex 3 upon activation with dMAO (dried methylaluminoxane) led to the combination of high activity and controlled isotacticity in the polymerization of 1-hexene, 4-methyl-1-pentene, and propylene .…”