1232366-57-2Relevant articles and documents
Synthesis of [(DPPNCH2CH2)3N]3- molybdenum complexes (DPP = 3,5-(2,5-Diisopropylpyrrolyl)2C 6H3) and studies relevant to catalytic reduction of dinitrogen
Reithofer, Michael R.,Schrock, Richard R.,Mueller, Peter
, p. 8349 - 8358 (2010)
Molybdenum complexes that contain a new TREN-based ligand [(3,5-(2,5-diisopropyl-pyrrolyl)2C6H3NCH 2CH2)3N]3- ([DPPN3N] 3-) that are relevant to the catalytic reduction of dinitrogen have been prepared. They are [Bu4N]{[DPPN3N]MoN2}, [DPPN3N]MoN2, [DPPN3N]MoN=NH, {[DPPN 3N]MoN=NH2}[BArf4], [DPPN 3N]Mo≡N, {[DPPN3N]Mo≡NH}[BArf 4], and {[DPPN3N]MoNH3}[BArf 4]. NMR and IR data for [Bu4N]{[DPPN3N]MoN 2} and [DPPN3N]MoN2 are close to those reported for the analogous [HIPTN3N]3- compounds (HIPT = hexaisopropylterphenyl), which suggests that the degree of reduction of dinitrogen is virtually identical in the two systems. However, X-ray studies and several exchange studies support the conclusion that the apical pocket is less protected in [DPPN3N]Mo complexes than in [HIPTN3N]Mo complexes. For example, 15N/14N exchange studies showed that exchange in [DPPN3N]MoN2 is relatively facile (t 1/2 a 1 h at 1 atm) and depends upon dinitrogen pressure, in contrast to the exchange in [HIPTN3N]MoN2. Several of the [DPPN3N]Mo complexes, e.g., the [DPPN3N]MoN2 and [DPPN3N]MoNH3 species, are also less stable in solution than the analogous parent [HIPTN3N]Mo complexes. Four attempted catalytic reductions of dinitrogen with [DPPN3N]MoN yielded 2.53 ± 0.35 equiv of total ammonia. These studies reveal more than any other just how sensitive a successful catalytic reduction is to small changes in the triamidoamine supporting ligand.
