Phenylene‐bridged β‐Ketoiminate Dilanthanide Aryloxides: Synthesis,Structure, and Catalytic Activity for Addition of Amines to Carbodiimides |
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Authors: | Yubiao Hong Yu Zheng Mingqiang Xue Yingming Yao Yong Zhang Qi Shen |
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Institution: | College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China |
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Abstract: | The synthesis and reactivity of a series of bimetallic lanthanide aryloxides stabilized by a p‐phenylene‐bridged bis(β‐ketoiminate) ligand is presented. The reaction of 1,4‐diaminobenzene with acetylacetone in a 1:2.5 molar ratio in absolute ethanol gave the compound 1,4‐bis(4‐imino‐2‐pentanone)benzene ( 1 ) (LH2) in high yield. Compound 1 reacted with (ArO)3Ln(THF)2 (ArO = 2,6‐tBu2‐4‐MeC6H2O, THF = tetrahydrofuran) in a 1:2 molar ratio in THF, after workup, to give the corresponding dilanthanide aryloxides LLn(OAr)2(THF)]2 Ln = Yb ( 2 ), Y ( 3 ), Sm ( 4 ), Nd ( 5 ), La ( 6 )] in high isolated yields. Compound 1 and complexes 2 – 6 were fully characterized, including X‐ray crystal structure analyses for complexes 2 , 3 , 5 , and 6 . Complexes 2 – 6 can be used as efficient pre‐catalysts for catalytic addition of amines to carbodiimides, and the ionic radii of the central metal atoms have a significant effect on the catalytic activity with the increasing sequence of La ( 6 ) < Nd ( 5 ) ≈ Sm ( 4 ) < Y ( 3 ) ≈ Yb ( 2 ). The catalytic addition reaction with 2 showed a good scope of substrates including primary and secondary amines. |
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Keywords: | Phenylene‐bridged β ‐ketoiminate Dilanthanide aryloxide Catalytic activity Guanidine |
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