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Title: Insertion Reactions of Phenyl Isocyanate Into Hafnium Nitrogen Bonds: Synthesis and Reactivity of Hafnium Complexes Bearing Substituted Pyrrolyl Ligands
Authors: Hsieh, K. C.;Lee, W. Y.;Lai, C. L.;Hu, Ching-Han;Lee, H. M.;Hung, J. H.;Peng, S. M.;Lee, G. H.
Contributors: 化學系
Date: 2004-10
Issue Date: 2012-05-03T06:17:51Z
Publisher: Elsevier
Abstract: A bis(diethylamido)hafnium compound [C4H3N(CH2NMe2)-2]2Hf(NEt2)2 (1) has been prepared in 79% yield by reacting Hf(NEt2)4 with 2 equiv. of [C4H3NH(CH2NMe2)-2] in heptane via deamination. Reacting compound 1 with 2 equiv. of phenyl isocyanate at room temperature in diethyl ether results in the PhNCO being inserted seletively into hafnium–NEt2 bonds to generate [C4H3N(CH2NMe2)-2]2Hf[PhNC(NEt2)O]2 (2) in 56% yield. Similarly, while reacting 1 with 2 equiv. of phenyl isocyanate for a week in toluene produces a mixture of 2 and [C4H3N(CH2NMe2)-2]Hf[PhNC(NEt2)O]3 (3). For comparison, reacting Hf(NEt2)4 with 4 equiv. of PhNCO in a toluene solution at room temperature results in the PhNCO inserted into Hf–N bonds, and forms a tetrakis-ureato hafnium compound Hf[PhNC(NEt2)O]4 (4) in 88% yield. A theoretical calculation found that the unpaired electrons of the ureato fragments of 2 are resonance delocalized between the C–O, C–NPh, and C–NEt2 bonds, which are all partially doubly bonded.
Relation: J. Organometallic Chem., 689(21): 3362-3369
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