Bis[μ-bis(2,6-diisopropylphenyl) phosphato-κ2O: O ′]bis[(2,2′-bipyridine-κ2N, N ′)lithium] toluene disolvate and its catalytic activity in ring-opening polymerization of -caprolactone and l -dilactide

The solvated centrosymmmtric title compound, [Li₂(C₂₄H₃₄O₄P)₂(C₁₀H₈N₂)₂]·2C₇H₈, was formed in the reaction between {Li[(2,6-ⁱPr₂C₆H₃-O)₂POO](MeOH)₃}(MeOH) and 2,2′-bipyridine (bipy) in toluene. The structure has monoclinic (P2₁/n) symmetry at 120 K and the asymmetric unit consists of half a complex molecule and one molecule of toluene solvent. The diaryl phosphate ligand demonstrates a μ-κO:κO′-bridging coordination mode and the 2,2′-bipyridine ligand is chelating to the Li⁺ cation, generating a distorted tetrahedral LiN₂O₂ coordination polyhedron. The complex exhibits a unique dimeric Li₂O₄P₂ core. One isopropyl group is disordered over two orientations in a 0.621 (4):0.379 (4) ratio. In the crystal, weak C—H...O and C—H...π interactions help to consolidate the packing. Catalytic systems based on the title complex and on the closely related complex {Li[(2,6-ⁱPr₂C₆H₃-O)₂POO](MeOH)₃}(MeOH) display activity in the ring-opening polymerization of ∊-caprolactone and L-dilactide.