Well-defined Phosphate Yttrium Dialkyl Complexes for Catalytic Stereo-Controllable 1,4-Polymerization of Isoprene

Oxygen ligation is envisioned to provide a stable and distinctive coordination environment to the strongly oxophilic rare-earth metals. However, the well-defined dialkyl complexes bearing oxyanion ancillary ligand had been rarely addressed for the instability of the complexes and the shortage of easily available ligands. Herein, we report the synthesis of phosphate ligated dialkyl yttrium complexes (PYR2) featuring a high stability and a tunable ligand. Treated with the borate reagent, the phosphate yttrium complex displays high activity and selectivity in the catalytic cis-1,4-polymerization of isoprene (up to 96.5%). Furthermore, using AlMe3 as an additive, the stereoselectivity switches to trans-1,4-polymerization (up to 92.0%).