163929-87-1Relevant articles and documents
Base-catalyzed dinitrogen cleavage by molybdenum amides
Trai, Yi-Chou,Cummins, Christopher C.
, p. 63 - 69 (2008/10/08)
The amides Mo(NRAr)3 (R=CMe3 or C(CD3)2CH3, Ar=3,5-C6H3Me2) and HMo(η2-Me2CNAr)(NRAr)2 (R=CHMe2 or CH(CD3)2, Ar=3,5-C6H3Me2) are known to effect the six-electron reductive cleavage of dinitrogen in the absence of added reagents to provide terminal nitrido molybdenum complexes of formula NMo(NRAr)3. However, this reaction typically has required a lengthy incubation period at -35°C during which N2 uptake takes place. This work reports on the catalytic effect of addition of stoichiometric amounts of N-heterocyclic bases such as 2,6-dimethylpyrazine, 1-methylimidazole, 4-dimethylaminopyridine (DMAP), and pyridine itself. Certain combinations of molybdenum amide and base lead to complete conversion to NMo(NRAr)3 within minutes at 25°C, 1 atm of N2, in ether or n-pentane solution. Monitoring of reaction progress and probing for possible intermediates has been carried out using 2H NMR spectroscopy, while taking advantage of samples labeled with CD3 groups. In some cases the 2H NMR data are in accord with intermediate base adduct formation, while in other cases adducts are not observed. The effect of potassium hydride in THF as the added base similarly has been investigated. 2002 Elsevier Science B.V. All rights reserved.
Dinitrogen cleavage by three-coordinate molybdenum(III) complexes: Mechanistic and structural data
Laplaza, Catalina E.,Johnson, Marc J. A.,Peters, Jonas C.,Odom, Aaron L.,Kim, Esther,Cummins, Christopher C.,George, Graham N.,Pickering, Ingrid J.
, p. 8623 - 8638 (2007/10/03)
The synthesis and characterization of the complexes Mo[N(R)Ar]3 (R = C(CD3)2CH3, Ar = 3,5-C6H3Me2), (μ-N2){Mo[N(R)Ar]3}2, (μ-15N2){Mo[N(R)Ar]3}2, NMo[N(R)Ar]3, 15NMo[N(R)Ar]3, Mo[N(t-Bu)Ph]3, (μ-N2){Mo[N(t-Bu)Ph]3}2, and NMo[N(t-Bu)Ph]3 are described. Temperature-dependent magnetic susceptibility data indicate a quartet ground state for Mo[N(R)Ar]3. Single-crystal X-ray diffraction studies for Mo[N(R)Ar]3 and NMo[N(t-Bu)Ph]3 are described. Extended X-ray absorption fine structure (EXAFS) structural studies for Mo[N(R)AR]3, (μN2){Mo[N(R)Ar]3}2, and NMo[N(R)AR]3 are reported. Temperature-dependent kinetic data are given for the unimolecular fragmentation of (μ-N2){Mo[N(R)Ar]3}2 to 2 equiv of NMo[N(R)Ar]3 and for the fragmentation of (μ-15N2){Mo[N(R)AR]3}2 to 2 equiv of 15NMo[N(R)AR]3. The temperature dependence of the 15N2 isotope effect for the latter N2 cleavage process was fitted to a simple harmonic model, leading to a prediction for the difference in NN stretching frequencies for the two isotopomers. The latter prediction was consistent with the Raman spectroscopic data for (μ-N2){Mo[N(R)Ar]3}2 and (μ-15N2){Mo[N(R)Ar]3}2. The Raman spectroscopic data and EXAFS results are both consistent with an NN bond order of approximately 2 in (μ-N2){Mo[N(R)Ar]3}2. Temperature-dependent magnetic susceptibility data consistent with a triplet ground state are given for (μ-N2){Mo[N(t-Bu)Ph]3}2.
Cleavage of the nitrous oxide NN bond by a three-coordinate molybdenum(III) complex
Laplaza, Catalina E.,Odom, Aaron L.,Davis, William M.,Cummins, Christopher C.,Protasiewicz, John D.
, p. 4999 - 5000 (2008/10/08)
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