The polymerization of ocimene has been first achieved by half-sandwich rare-earth metal dialkyl complexes in combination with activator and Al(i) Bu3 . The regio- and stereoselectivity in the ocimene polymerization can be controlled by tuning the cyclopentadienyl ligand and the central metal of the complex. The chiral cyclopentadienyl-ligated Sc complex 1 prepares syndiotactic cis-1,4-polyocimene (cis-1,4-selectivity up to 100%, rrrr = 100%), while the corresponding Lu, Y, and Dy complexes 2-4 and the achiral pentamethylcyclopentadienyl Sc, Lu, and Y complexes 5-7 afford isotactic trans-1,2-polyocimenes (trans-1,2-selectivity up to 100%, mm = 100%).

Isoprene polymerization and copolymerization with ethylene can be carried out by using cationic half-sandwich fluorenyl scandium catalysts in situ generated from halfsandwich fluorenyl scandium dialkyl complexes Flu'Sc(CH 2 Si-Me 3 ) 2 (THF) n , activator, and Al i Bu 3 under mild conditions. In the isoprene polymerization, all of these cationic half-sandwich fluorenyl scandium catalysts exhibit high activities (up to 1.89 3 10 7 g/mol Sc h) and mainly cis21,4 selectivities (up to 93%) under similar conditions. In contrast, these catalysts showed different activities and regio-/stereoselectivities being significantly dependent on the substituents of the fluorenyl ligands in the copolymerization of isoprene with ethylene under an atmosphere of ethylene (1 atm) at room temperature, affording the random copolymers with a wide range of cis21,4-isoprene contents (IP content: 64 2 97%, cis21,4-IP units: 65 2 79%) or almost alternating copolymers containing mainly 3,4-IP-alt-E or/and cis21,4-IP-alt-E sequences. Moreover, novel high performance polymers have been prepared via selective epoxidation of the vinyl groups of the 1,4-isoprene units in the IP-E copolymers.

This review covers key developments in the design of post-metallocene transition metal complexes (precatalysts) bearing tridentate chelating ligands and their application in olefin polymerization.

The mild and efficient hydroxytrifluoromethylation of alkenes with bromotrifluoromethane (CF3Br) and atmospheric oxygen mediated by cobalt-tertiary amine is described. This reaction proceeds with broad substrate scope and good functional group compatibility. Mechanistic studies indicate that the reaction proceeds through a radical pathway, which is enabled by combination of the previously unexplored highly efficient N-isopropyl-N,2-dimethylpropan-2-amine with Co­(II) for the single electron reduction of CF3Br to CF3 radical.

Cationic half-sandwich rare-earth metal alkyl species were first used for the coordination–insertion polymerization and copolymerization of aryl isocyanides.