Insertion reactions of phenyl isocyanate into hafnium nitrogen bonds: Synthesis and reactivity of hafnium complexes bearing substituted pyrrolyl ligands

Kun Chun Hsieh, Wen Yi Lee, Chun Liang Lai, Ching-Han Hu, Hon Man Lee, Jui-Hsien Huang, Shie Ming Peng, Gene Hsing Lee

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Abstract

A bis(diethylamido)hafnium compound [C4(CH2NMe 2)-2]2Hf(NEt2)2 (1) has been prepared in 79% yield by reacting Hf(NEt2)4 with 2 equiv. of [C4H(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 [C4(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 [C4(CH2NMe 2)-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.

Original languageEnglish
Pages (from-to)3362-3369
Number of pages8
JournalJournal of Organometallic Chemistry
Volume689
Issue number21
DOIs
Publication statusPublished - 2004 Oct 15

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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