Syntheses, Structures, And Catalytic Activities Of The Anionic Heterobimetallic Rare-Earth Metal Complexes Supported By Pyrrolyl-Substituted 1,2-Diimino Ligands

A series of the anionic heterobimetallic rare-earth metal complexes supported by trans- or chiral pyrrolyl-substituted 1,2-diimino ligands were synthesized in good yields via reactions of [(Me3Si)(2)N](3)RE(mu-Cl)Li(THF)(3) with the corresponding 1,2-diimino proligands. Reactions of [(Me3Si)(2)N](3)RE(mu-Cl)Li(THF)(3) with 2 equiv of trans-1,2-bis(pyrrol-2-ylmethylene)-1,2-diphenylethanediamine (H2L1) afforded the discrete ion-pair rare-earth metal complexes [Li-(THF)(4)](+)[(L-1)(2)RE](-) (RE = Sm(5), Dy(6), Er(7)). Reactions of [(Me3Si)(2)N](3)RE(mu-Cl)Li(THF)(3) with 2 equiv of (R,R)-1,2-bis(pyrrol-2-ylmethylene)-1,2-diphenylethanediamine (1121,2) gave the heterobimetallic rare-earth metal complexes (L-2)(2)RELi(THF)(2) (RE = Sm(8), Y(9)). When the rare-earth metal is Er, the chiral linear rare-earth coordination polymer {(L-2)(2)ErLi}(n) (10) was obtained. Reactions of [(Me3SO2N](3)RE(mu-Cl)Li(THF)(3) with 2 equiv of trans-1,2-bis(pyrrol-2-ylmethyleneamino)cyclohexane (H2L3) gave the heterobimetallic rare-earth metal complexes (L-3)(2)RELi(THF)(2) (RE = Pr (11), Sm(12), Eu(13)). Reactions of [(Me3SO2N](3)RE(mu-Cl)Li(THF)(3) with 2 equiv of (R,R)-1,2-bis(pyrrol-2-ylmethyleneamino)-cyclohexane (H2L4) also gave the heterobimetallic rare-earth metal complexes (L-4)(RELi)-R-2(THF)(2) (Ln = Pr(14), Sm(15)). All complexes were characterized by spectroscopic methods and elemental analyses, and complexes 5-11, 13, and 14 were further determined by single-crystal X-ray diffraction. The catalytic properties of racemic rare-earth metal complexes on cyanosilylation of ketones were examined, and results showed that the above complexes could effectively catalyze the cyanosilylation of ketones. Chiral rare-earth metal complexes as catalysts for the enantioselective epcoddation of alpha,beta-unsaturated ketones were also examined to afford the chiral epoxides in high yields with moderate enantioselectivities.