博彩平台

Mingqiang Xue*^a （薛明强），Yu Zheng,^a   Yubiao Hong,^a  Yingming Yao,^a   Fan Xu*^a （徐凡），Yong Zhang^a and  Qi Shen^a

Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Dushu Lake Campus, Soochow University, Suzhou 215123, People's Republic of China

Dalton Trans., 2015,44, 20075-20086

Reduction reactions of bis(β-diketiminate)lanthanide(III) chlorides formed in situ by reactions of anhydrous LnCl₃ with 2 equiv. of sodium salt of the β-diketiminate ligand in THF with a Na/K alloy afforded a series of bis(β-diketiminate)lanthanide(II) complexes LnL₂(THF)_n (L = L^2,6-Me₂ = [N(2,6-Me₂C₆H₃)C(Me)]₂CH⁻, n = 1, Ln = Eu(1); L = L^2,4,6-Me₃ = [N(2,4,6-Me₃C₆H₂)C(Me)]₂CH⁻, n = 1, Ln = Eu (2); L = L^2,6-iPr₂ = [N(2,6-ⁱPr₂C₆H₃)C(Me)]₂CH⁻, n = 0, Ln = Eu (3), Sm (4); L = L^2,6-ipr_2Ph = [(2,6-ⁱPr₂C₆H₃)NC(Me)CHC(Me)N(C₆H₅)]⁻, n = 0, Ln = Eu (5), Yb(6); L = L^2-Me = [N(2-MeC₆H₄)C(Me)]₂CH⁻, n = 1, Ln = Yb (7)) in high yields. All the complexes, especially the complexes of Sm^II (4) and Eu^II (5), were found to be excellent pre-catalysts for catalytic addition of amines to carbodiimides to multi-substituted guanidines with a wide scope of substrates. The activity depends both on the central metals and the ligands with the active sequence of Yb^II < Eu^II and Eu^II < Sm^II and L^2,6-Me₂ < L^2,4,6-Me₃ ∼ L^2,6-iPr₂ < L^2,6-ipr_2Ph for the ligands. The mechanistic study by the isolation of guanidinate species and their reactivity revealed that Eu^II monoguanidinate complexes Eu(L^2,6-Me₂)[(C₆H₅N)C(NHCy)(NCy)](DME) (8) and Eu(L^2,6-ipr_2Ph)[(C₆H₅N)C(NHCy)(NCy)](THF)₂ (9) should be the key active intermediates for the systems with Eu^II complexes and a Yb^III bis(guanidinate) complex Yb(L^2-Me)[(C₆H₅N)C(NHCy)(NCy)]₂(11)for the system using a Yb^II complex.

链接：//pubs.rsc.org/en/Content/ArticleLanding/2015/DT/C5DT03674G#!divAbstract