256240-25-2Relevant academic research and scientific papers
Nitrogen fixation to cyanide at a molybdenum center
Curley, John J.,Cozzolino, Anthony F.,Cummins, Christopher C.
, p. 2429 - 2432 (2011/06/09)
Facile methoxymethylation of N2-derived nitride NMo(N[ tBu]Ar)3 provided the imido cation [MeOCH 2NMo(N[tBu]Ar)3]+ as its triflate salt in 88% yield. Treatment of the latter with LiN(SiMe3) 2 provided blue methoxyketimide complex MeO(H)CNMo(N[ tBu]Ar)3 in 95% yield. Conversion of the latter to the terminal cyanide complex NCMo(N[tBu]Ar)3, which was the subject of a single-crystal X-ray diffraction study, was accomplished in 51% yield upon treatment with a combination of SnCl2 and Me 2NSiMe3.
Shining light on dinitrogen cleavage: Structural features, redox chemistry, and photochemistry of the key intermediate bridging dinitrogen complex
Curley, John J.,Cook, Timothy R.,Reece, Steven Y.,Mueller, Peter,Cummins, Christopher C.
, p. 9394 - 9405 (2009/02/02)
The key intermediate in dinitrogen cleavage by Mo(N[t-Bu]Ar)3, 1 (Ar = 3,5-C6H3Me2), has been characterized by a pair of single crystal X-ray structures. For the first time, the X-ray crystal structure of (μ-N2)[Mo(N[t-Bu]Ar)3]2, 2, and the product of homolytic fragmentation of the N-N bond, N≡Mo(N[t-Bu] Ar)3, are reported. The structural features of 2 are compared with previously reported EXAFS data. Moreover, contrasts are drawn between theoretical predictions concerning the structural and magnetic properties of 2 and those reported herein. In particular, it is shown that 2 exists as a triplet (S = 1) at 20°C. Further insight into the bonding across the MoNNMo core of the molecule is obtained by the synthesis and structural characterization of the one- and two-electron oxidized congeners, (μ-N2)[Mo(N[t-Bu]Ar) 3]2[B(ArF)4], 2[B(Ar F)4] (ArF = 3,5-C6H 3(CF3)2) and (μ-N2)[Mo(N[t-Bu]Ar) 3]2[B(ArF)4]2, 2[B(ArF)4]2, respectively. Bonding in these three molecules is discussed in view of X-ray crystallography, Raman spectroscopy, electronic absorption spectroscopy, and density functional theory. Combining X-ray crystallography data with Raman spectroscopy studies allows the N-N bond polarization energy and N-N internuclear distance to be correlated in three states of charge across the MoNNMo core. For 2[B(ArF) 4], bonding is symmetric about the μ-N2 ligand and the N-N polarization is Raman active; therefore, 2[B(ArF)4] meets the criteria of a Robin-Day class III mixed-valent compound. The redox couples that interrelate 2, 2+, and 22+ are studied by cyclic voltammetry and spectroelectrochemistry. Insights into the electronic structure of 2 led to the discovery of a photochemical reaction that forms N≡Mo(N[t-Bu]Ar)3 and Mo(N[t-Bu]Ar)3 through competing N-N bond cleavage and N2 extrusion reaction pathways. The primary quantum yield was determined to be Φp = 0.05, and transient absorption experiments show that the photochemical reaction is complete in less than 10 ns.
A nitridoniobium(V) reagent that effects acid chloride to organic nitrile conversion: Synthesis via heterodinuclear (Nb/Mo) dinitrogen cleavage, mechanistic insights, and recycling
Figueroa, Joshua S.,Piro, Nicholas A.,Clough, Christopher R.,Cummins, Christopher C.
, p. 940 - 950 (2007/10/03)
The transformation of acid chlorides (RC(O)Cl) to organic nitriles (RC≡N) by the terminal niobium nitride anion [N≡Nb(N[Np]Ar) 3]- ([1a-N]-, where Np = neopentyl and Ar = 3,5-Me2C6H3) via i
A cycle for organic nitrile synthesis via dinitrogen cleavage
Curley, John J.,Sceats, Emma L.,Cummins, Christopher C.
, p. 14036 - 14037 (2007/10/03)
In the presence of NaH, the reaction between N2 and Mo(N[t-Bu]Ar)3 (Ar = 3,5-C6H3Me2) proceeds at room temperature to afford NMo(N[t-Bu]Ar)3 (95%). Lewis acidic silyl triflates (Me3/s
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.
Reactions of organic nitriles with a three-coordinate molybdenum (III) complex and with a related molybdaziridine-hydride
Tsai, Yi-Chou,Stephens, Frances H.,Meyer, Karsten,Mendiratta, Arjun,Gheorghiu, Mircea D.,Cummins, Christopher C.
, p. 2902 - 2913 (2008/10/08)
Reactions of nitriles RCN with the sterically encumbered Mo(N[t-Bu]Ar)3 (1, Ar = 3,5-C6H3Me2) or the somewhat less hindered Mo(H)(η2-Me2CNAr)(N[i-Pr]Ar)2 (2) have been investigated. Where R = Me or Ph, reaction with 1 results in reductive nitrile coupling and the formation of a diiminato product [μ-NC(R)C(R)N][1]2. In contrast, reaction of 1 with Me2NCN surprisingly results in a stable, albeit highly congested, η2 adduct of the nitrile. When the less sterically hindered 2 is used, reaction with PhCN gives the diiminato product analogous to the one mentioned for the tert-butyl system, [μ-NC(Ph)C(Ph)N] [Mo(N[i-Pr]Ar)3]2, where molybdaziridine-hydride 2 has provided access to the three-coordinate Mo(N[i-Pr]Ar)3 (3) moiety. Use of a more bulky nitrile such as MesCN (Mes = 2,4,6-C6H2Me3) results in formation of a bis-η1 compound, (η1-MesCN)2[3]. Use of 9-anthracenylcarbonitrile results in head-to-tail C-C coupling of two monomers via the anthracenyl moiety. Detailed variable-temperature EPR and 2H NMR data are included for both molybdenum-containing starting materials and selected reaction intermediates and products.
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.
