@article {23411,
	title = {Side-on End-on Bound Dinitrogen: An Activated Bonding Mode That Facilitates Functionalizing Molecular Nitrogen},
	journal = {Accounts of Chemical Research},
	volume = {42},
	year = {2009},
	month = {Jan},
	pages = {127-133},
	type = {Review},
	abstract = {<p>Molecular nitrogen is the source of all of the nitrogen necessary to sustain life on this planet. How it is incorporated into the biosphere is complicated by its intrinsic inertness. For example, biological nitrogen fixation takes N-2 and converts it into ammonia using various nitrogenase enzymes, whereas industrial nitrogen fixation converts N-2 and H-2 to NH3 using heterogeneous iron or ruthenium surfaces. In both cases, the processes are energy-intensive. Is it possible to discover a homogeneous catalyst that can convert molecular nitrogen into higher-value organonitrogen compounds using a less energy-intensive pathway? If this could be achieved, it would be considered a major breakthrough in this area. In contrast to carbon monoxide, which is reactive and an important feedstock in many homogeneous catalytic reactions, the ischelectronic but inert N-2 molecule is a very poor ligand and not a common industrial feedstock, except for the above-mentioned industrial production of NH3. Because N-2 is readily available from the atmosphere and because nitrogen is an essential element for the biosphere, attempts to discover new processes involving this simple small molecule have occupied chemists for over a century. Since the first discovery of a dinitrogen complex in 1965, inorganic chemists have been key players in this area and have contributed much fundamental knowledge on structures, binding modes, and reactivity patterns. For the most part, the synthesis of dinitrogen complexes relies on the use of reducing agents to generate an electron-rich intermediate that can interact with this rather inert molecule. In this Account, a facile reaction of dinitrogen with a ditantalum tetrahydride species to generate the unusual side-on end-on bound N-2 moiety is described. This particular process is one of a growing number of new, milder ways to generate dinitrogen complexes. Furthermore, the resulting dinitrogen complex undergoes a number of reactions that expand the known patterns of reactivity for coordinated N-2. This Account reviews the reactions of ([NPN]Ta)(2)(mu-H)(2)(mu-eta(1):eta(2)-N-2), 2 (where NPN = PhP(CH2SiMe2NPh)(2)), with a variety of simple hydride reagents, E-H (where E-H = R2BH, R2AlH, RSiH3, and Cp2ZrCl(H)), each of which results in the cleavage of the N-N bond to form various functionalized imide and nitride moieties. This work is described in the context of a possible catalytic cycle that in principle could generate higher-value nitrogen-containing materials and regenerate the starting ditantalum tetrahydride. How this fails for each particular reagent is discussed and evaluated.</p>},
	keywords = {ammonia, CLEAVAGE, CONVERSION, COORDINATED N-2 LIGAND, H-2, HYDROSILYLATION, MOLYBDENUM, REACTIVITY, REDUCTION, TANTALUM COMPLEX},
	isbn = {0001-4842},
	author = {Fryzuk, MD}
}
@article {1579,
	title = {N-N splitting of a functionalized mu-eta(1):eta(2) coordinated N-2 ligand leading to a mu-nitrido mu-imido core: mechanistic insight from DFT},
	journal = {Dalton Transactions},
	number = {9},
	year = {2006},
	note = {ISI Document Delivery No.: 021NKTimes Cited: 5Cited Reference Count: 35},
	pages = {1137-1140},
	type = {Article},
	abstract = {Silylation of a dinuclear tantalum complex containing a side- on end-on coordinated dinitrogen ligand initiates a sequence of reactions ultimately leading to a bis(mu-imido) structure. DFT is employed to determine the energetics of the entire reaction cascade. Particular emphasis is put on the unprecedented N-N cleavage reaction of the functionalized, mu-eta(1):eta(2) coordinated dinitrogen ligand. A mechanism for this reaction is derived theoretically and the corresponding transition state is determined.},
	keywords = {ammonia, ATOMS, BOND-CLEAVAGE, END-ON, MOLECULAR CALCULATIONS, POTENTIALS, REACTIVITY, SIDE-ON, SPECTROSCOPIC PROPERTIES, TANTALUM DINITROGEN COMPLEX},
	isbn = {1477-9226},
	url = {<Go to ISI>://000235989700003},
	author = {Studt, F. and MacKay, B. A. and Fryzuk,Michael D. and Tuczek, F.}
}
@article {1185,
	title = {Functionalization and cleavage of coordinated dinitrogen via hydroboration using primary and secondary boranes},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {83},
	number = {4},
	year = {2005},
	note = {ISI Document Delivery No.: 921DLTimes Cited: 14Cited Reference Count: 30},
	month = {Apr},
	pages = {315-323},
	type = {Article},
	abstract = {The reaction of the side-on, end-on ditantalum dinitrogen complex ([NPN]Ta)(2)(mu-eta(1):eta(2)-N-2)(mu-H)(2) (where NPN = PhP(CH2SiMe2NPh)(2)) with a variety of secondary and primary boranes is reported. With 9-BBN, hydroboration of the Ta2N2 unit occurs via B-H addition, which in turn triggers a cascade of reactions that result in N-N bond cleavage, ancillary ligand rearrangement involving silicon group migration, and finally elimination of benzene from the N-Ph group and a B-H moiety to generate the imide-nitride derivative. In the presence of excess 9-BBN, the Lewis acid - base adduct of the imide-nitride ([NP mu-N]Ta(=NBC8H14)(mu-NB(H)C8H14)Ta[NPN]) is formed. A similar set of reactions is observed for dicyclohexylborane (Cy2BH), which hydroborates the dinitrogen complex to generate [NPN]Ta(H)(mu-eta(1):eta(2)-NNBCy2)(mu-H)(2)Ta[NPN], followed by loss of H-2 and silicon group migration to yield the imide-nitride [NP mu-N]Ta(=NBCy2)(mu-N)(Ta[NPN]. With thexyl borane (H2BCMe2CHMe2), a similar sequence of reactions is suggested starting with hydroboration to generate [NPN]Ta(H)(mu-eta(1):eta(2)-NNB(H)C6H13)(mu-H)(2)Ta[NPN], followed by loss of H-2 and ancillary ligand rearrangement. When bis(pentafluorophenyl)borane (HB(C6F5)(2)) is used, no hydroboration of coordinated N-2 is observed, rather simple adduct formation to give ([NPN]Ta)(2)(mu-eta(1):eta(2)-NN-B(H)(C6F5)(2))(mu-H)(2) occurs.},
	keywords = {ACTIVATION, ammonia, CHEMISTRY, DINITROGEN, END-ON, FIXATION, hydroboration, METAL-COMPLEXES, MOLECULAR NITROGEN, MOLYBDENUM, N-2, N-N bond cleavage, SIDE-ON, tantalum},
	isbn = {0008-4042},
	url = {<Go to ISI>://000228744300008},
	author = {MacKay, B. A. and Johnson, S. A. and Patrick, B. O. and Fryzuk,Michael D.}
}
@article {4331,
	title = {X-ray photoelectron spectroscopy studies of the reduction of MoO3 thin films by NH3},
	journal = {Applied Surface Science},
	volume = {136},
	number = {1-2},
	year = {1998},
	note = {ISI Document Delivery No.: 133ZGTimes Cited: 7Cited Reference Count: 33},
	month = {Oct},
	pages = {147-158},
	type = {Article},
	abstract = {X-ray photoelectron spectroscopy (XPS) has been used to gain insight into surface reaction pathways associated with the nitridation by NH3 of MoO3 thin films grown on metallic substrates. The samples formed can be seen as model hydrodenitrogenation (HDN) catalysts, but the more-controlled surface morphology allows spectral features to be studied in the absence of charging effects that can interfere with such measurements on high-area samples. Observed core level and valence spectra are consistent with the MoO3 being reduced, but the degree of reduction depends on the reaction temperature. Heating to 350 degrees C indicates some conversion to Mo(+5) and {\textquoteright}O-rich{\textquoteright} Mo(+4) components, while heating to 450 degrees C and to 700 degrees C give respectively a {\textquoteright}N-rich{\textquoteright} Mo(+4) form and a Mo(+3) oxynitride as the dominant components. It is concluded that the nitridation of MoO3 by NH3 involves initial hydrogenation, with subsequent elimination of water, and the effective replacement of O by N as the reduction continues. Surface compositions determined here during the nitridation process contrast with conclusions reached previously for the evolution of bulk phases as deduced by X-ray diffraction. (C) 1998 Elsevier Science B.V. All rights reserved.},
	keywords = {ADSORPTION, ammonia, Auger, CATALYSTS, DECOMPOSITION, HYDRODENITROGENATION, MOLYBDENUM NITRIDES, MOO3, NH3, REDUCTION, SURFACE-AREA, X-ray photoelectron spectroscopy, XPS},
	isbn = {0169-4332},
	url = {<Go to ISI>://000076717000022},
	author = {Leung, Y. L. and Wong, P. C. and Mitchell, K. A. R. and Smith, K. J.}
}
