Key Laboratory of Organic Synthesis of Jiangsu Province, Department of Chemistry and Chemical Engineering, Dushu Lake Campus. and Soochow University, Suzhou 215123, People's Republic of China.
Dalton Trans. 2013 Apr 28;42(16):5890-901. doi: 10.1039/c3dt33069a.
Various lanthanide aryloxide complexes supported by bridged bis(amidinate) ligand L, LLnOAr(DME) (L = Me3SiNC(Ph)N(CH2)3NC(Ph)NSiMe3, DME = dimethoxyethane, Ln = Y, Ar = 2,6-(Me)2C6H3 (1), 2,6-((i)Pr)2C6H3 (2), 2,6-((t)Bu)2-4-(Me)C6H2 (3); Ar = 2,6-((t)Bu)2-4-(Me)C6H2, Ln = Nd (4), Sm (5), Yb (6)) were synthesized, and complexes 1, 2 and 4–6 were characterized by single crystal X-ray diffraction. All the complexes are efficient precatalysts for catalytic addition of amines to carbodiimides. The catalytic activity is influenced by lanthanide metals and the aryloxide groups (Nd (4) Sm (5) < Y (3) Yb (6) and -2,6-(Me)2C6H3 < -2,6-((i)Pr)2C6H3 < -2,6-((t)Bu)2-4-(Me)C6H2). The catalytic addition reaction with 3 showed a good scope of substrates. The mechanism investigation revealed the real active intermediate being the monoguanidinate complexes supported by an aryloxide and an amidine-functionalized amidinate group, L′Ln[O2,6-((t)Bu)2-4-(Me)C6H2][RNCNHRN(Ar′)] (L′ = Me3SiNHC(Ph)N(CH2)3NC(Ph)NSiMe3, R = (i)Pr, Ar′ = phenyl, Ln = Yb (8), Y (11); R = Cy, Ar′ = phenyl, Ln = Yb (10), Y (12); R = (i)Pr, Ar′ = 4-ClC6H4, Ln = Yb (9)), which were isolated from the reactions of 6 (or 3) with amine and carbodiimide in a molar ratio of 1:1:1 and structurally characterized. The Ln-active group in the present precatalyst is a Ln–amidinate species, not the Ln–OAr group.
各种镧系芳氧基配合物由桥联双（酰胺基）配体 L、LLnOAr(DME)（L = Me3SiNC(Ph)N(CH2)3NC(Ph)NSiMe3，DME = 二甲氧基乙烷，Ln = Y，Ar = 2,6-(Me)2C6H3 (1)，2,6-((i)Pr)2C6H3 (2)，2,6-((t)Bu)2-4-(Me)C6H2 (3)；Ar = 2,6-((t)Bu)2-4-(Me)C6H2，Ln = Nd (4)，Sm (5)，Yb (6))合成，并通过单晶 X 射线衍射对配合物 1、2 和 4-6 进行了表征。所有配合物都是催化胺与碳二亚胺加成的有效前催化剂。催化活性受镧系金属和芳氧基基团的影响（Nd (4) Sm (5) < Y (3) Yb (6)和 -2,6-(Me)2C6H3 < -2,6-((i)Pr)2C6H3 < -2,6-((t)Bu)2-4-(Me)C6H2）。与 3 的催化加成反应具有良好的底物范围。机理研究表明，真正的活性中间体是由芳氧基和酰胺基化酰胺基配体支持的单胍基配合物，L′Ln[O2,6-((t)Bu)2-4-(Me)C6H2][RNCNHRN(Ar′)]（L′= Me3SiNHC(Ph)N(CH2)3NC(Ph)NSiMe3，R = (i)Pr，Ar′= 苯基，Ln = Yb (8)，Y (11)；R = Cy，Ar′= 苯基，Ln = Yb (10)，Y (12)；R = (i)Pr，Ar′= 4-ClC6H4，Ln = Yb (9)），它们是由 6（或 3）与胺和碳二亚胺以 1:1:1 的摩尔比反应得到的，并进行了结构表征。本前催化剂中的 Ln-活性基团是 Ln-酰胺基物种，而不是 Ln-OAr 基团。
