Molybdenum-catalyzed transformation of molecular dinitrogen into silylamine: Experimental and DFT study on the remarkable role of ferrocenyldiphosphine ligands

Hiromasa Tanaka, Akira Sasada, Tomohisa Kouno, Masahiro Yuki, Yoshihiro Miyake, Haruyuki Nakanishi, Yoshiaki Nishibayashi, Kazunari Yoshizawa

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93 Citations (Scopus)

Abstract

A molybdenum-dinitrogen complex bearing two ancillary ferrocenyldiphosphine ligands, trans-[Mo(N2)2(depf)2] (depf = 1,1′-bis(diethylphosphino)ferrocene), catalyzes the conversion of molecular dinitrogen (N2) into silylamine (N(SiMe3) 3), which can be readily converted into NH3 by acid treatment. The conversion has been achieved in the presence of Me 3SiCl and Na at room temperature with a turnover number (TON) of 226 for the N(SiMe3)3 generation for 200 h. This TON is significantly improved relative to those ever reported by Hidai's group for mononuclear molybdenum complexes having monophosphine coligands [J. Am. Chem. Soc.1989, 111, 1939]. Density functional theory (DFT) calculations have been performed to figure out the mechanism of the catalytic N2 conversion. On the basis of some pieces of experimental information, SiMe3 radical is assumed to serve as an active species in the catalytic cycle. Calculated results also support that SiMe3 radical is capable of working as an active species. The formation of five-coordinate intermediates, in which one of the N2 ligands or one of the Mo-P bonds is dissociated, is essential in an early stage of the N2 conversion. The SiMe 3 addition to a "hydrazido(2-)" intermediate having the NN(SiMe3)2 group will give a "hydrazido(1-)" intermediate having the (Me3Si)NN(SiMe3)2 group rather than a pair of a nitrido (-N) intermediate and N(SiMe3) 3. The N(SiMe3)3 generation would not occur at the Mo center but proceed after the (Me3Si)NN(SiMe3) 2 group is released from the Mo center. The flexibility of the Mo-P bond between Mo and depf would play a vital role in the high catalysis of the Mo-Fe complex.

Original languageEnglish
Pages (from-to)3498-3506
Number of pages9
JournalJournal of the American Chemical Society
Volume133
Issue number10
DOIs
Publication statusPublished - Mar 16 2011

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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