An amidato divalent ytterbium cluster: synthesis and molecular structure, its reactivity to carbodiimides and application in the guanylation reaction

作者：Gong, Chao; Ding, Hao; Lu, Chengrong; Zhao, Bei^*; Yao, Yingming^*

来源：Dalton Transactions, 2017, 46(18): 6031-6038.

DOI：10.1039/c7dt00871f

• RING-OPENING POLYMERIZATION
• EARTH-METAL AMIDES
• EPSILON-CAPROLACTONE POLYMERIZATION
• NATURAL GUANIDINE DERIVATIVES
• ONE-ELECTRON-TRANSFER
• AMINE N-H
• CATALYTIC ADDITION
• C-H
• LANTHANIDE COMPLEXES
• ORGANOLANTHANIDE COMPLEXES

A divalent ytterbium amidate 1 ([Yb3L6]center dot 2C(7)H(8) for short) was synthesized via amine-elimination of Yb [N(SiMe3)2] 2(TMEDA) with an amide proligand N-2,6-diisopropylphenylbenzamide HL (L = 2,6-(Pr2C6H3NC)-Pr-i(O)Ph) and structurally characterized to be a trinuclear symmetric cluster. Further studies on the reduction of (PrN)-Pr-i=C=(NPr)-Pr-i by complex 1 provide Yb(III) complex 2 in hexane-THF ([(YbL2)2(mu-(NPrCNPr)-Pr-i-Pr-i)][YbL3(THF)]center dot C7H8), which is composed of two subunits in a unit cell, one is a bridged Yb(III) carbene, just the same as complex 4 ([(YbL2)(2)(mu-(NPrCNPr)-Pr-i-Pr-i)]center dot 3C(7)H(8)) obtained in the same reaction in toluene, and the other is a homoleptic monomeric Yb(III) amidate (YbL3). It is also found that complex 2 decomposed to complex 3 ([ YbL3](2)center dot 2C(7)H(8)) and 4 at 90 degrees C in toluene. Complexes 1-4 were confirmed by X-ray structure determination. Furthermore, complex 4 was proved to be a more active species than its precursor 1 in the catalytic addition of amines to carbodiimides. Finally, complex 1 was found to be an excellent pre-catalyst for the guanylation reaction with a wide scope of substrates.

• 出版日期2017-5-14
• 单位苏州大学