Syntheses, Structures, and Catalytic Activities of the Anionic Heterobimetallic Rare-Earth Metal Complexes Supported by Pyrrolyl-Substituted 1,2-Diimino Ligands

• Published in: Inorganic chemistry Vol. 57; no. 16; pp. 10390 - 10400
• Main Authors: Wang, Wei, Wang, Xiaojia, Zhou, Shuangliu, Xu, Xiaolong, Du, Jun, Zhang, Lijun, Mu, Xiaolong, Wei, Yun, Zhu, Xiancui, Wang, Shaowu
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.08.2018
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.8b01556

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)2N]3RE­(μ-Cl)­Li­(THF)3 with the corresponding 1,2-diimino proligands. Reactions of [(Me3Si)2N]3RE­(μ-Cl)­Li­(THF)3 with 2 equiv of trans-1,2-bis­(pyrrol-2-ylmethylene)-1,2-diphenylethanediamine (H 2 L 1 ) afforded the discrete ion-pair rare-earth metal complexes [Li­(THF)4]+[(L 1 )2RE]− (RE = Sm­(5), Dy­(6), Er­(7)). Reactions of [(Me3Si)2N]3RE­(μ-Cl)­Li­(THF)3 with 2 equiv of (R,R)-1,2-bis­(pyrrol-2-ylmethylene)-1,2-diphenylethanediamine (H 2 L 2 ) gave the heterobimetallic rare-earth metal complexes (L 2 )2RELi­(THF)2 (RE = Sm­(8), Y­(9)). When the rare-earth metal is Er, the chiral linear rare-earth coordination polymer {(L 2 )2ErLi} n (10) was obtained. Reactions of [(Me3Si)2N]3RE­(μ-Cl)­Li­(THF)3 with 2 equiv of trans-1,2-bis­(pyrrol-2-ylmethyleneamino)­cyclohexane (H2 L 3 ) gave the heterobimetallic rare-earth metal complexes (L 3 )2RELi­(THF)2 (RE = Pr (11), Sm­(12), Eu­(13)). Reactions of [(Me3Si)2N]3RE­(μ-Cl)­Li­(THF)3 with 2 equiv of (R,R)-1,2-bis­(pyrrol-2-ylmethyleneamino)­cyclohexane (H2 L 4 ) also gave the heterobimetallic rare-earth metal complexes (L 4 )2RELi­(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 epoxidation of α,β-unsaturated ketones were also examined to afford the chiral epoxides in high yields with moderate enantioselectivities.