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Tungsten alkylidyne complexes with ancillary imidazolin-2-iminato and imidazolidin-2-iminato ligands and their use in catalytic alkyne metathesis

Authors
Journal
Journal of Organometallic Chemistry
0022-328X
Publisher
Elsevier
Publication Date
Volume
744
Identifiers
DOI: 10.1016/j.jorganchem.2013.03.035
Keywords
  • Alkylidyne Complexes
  • Carbyne Complexes
  • Alkyne Metathesis
  • Tungsten
  • Imidazolin-2-Iminato Ligands
  • Guanidines

Abstract

Abstract The imines 1,3-di-tert-butylimidazolidin-2-imine (10) and 4,5-dimethyl-1,3-di-tert-butylimidazolin-2-imine (14) were prepared starting from the corresponding N-heterocyclic carbenes 8 and 11 and trimethylsilyl azide or tert-butyl azide, respectively. Deprotonation of the imines 10 and 14 with methyl lithium and reaction with an equimolar amount of the tungsten benzylidyne complex [PhCW{OCMe(CF3)2}3(DME)] (16) (DME = 1,2-dimethoxyethane) afforded the complexes [PhCW(L){OCMe(CF3)2}2] (L = 1,3-di-tert-butylimidazolidin-2-iminato, 6; L = 4,5-dimethyl-1,3-di-tert-butylimidazolin-2-iminato, 7), which were characterized by 1H, 13C{1H} and 19F{1H} NMR spectroscopy and by elemental and X-ray diffraction analysis. Complexes 6 and 7 are efficient catalysts for the homocoupling of 3-pentynyl benzyl ether (17) at room temperature in the presence of 5 Å molecular sieve and at low catalyst loadings (1 mol%).

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