Dinitrogen Cleavage and Hydrogenation by a Trinuclear Titanium Polyhydride Complex

Science ◽  
2013 ◽  
Vol 340 (6140) ◽  
pp. 1549-1552 ◽  
Author(s):  
Takanori Shima ◽  
Shaowei Hu ◽  
Gen Luo ◽  
Xiaohui Kang ◽  
Yi Luo ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ambient Temperature ◽  
Triple Bond ◽  
Partial Hydrogenation ◽  
Computational Studies ◽  
X Ray ◽  
Temperature And Pressure ◽  
Dinitrogen Cleavage ◽  
Intramolecular Hydrogen

Both the Haber-Bosch and biological ammonia syntheses are thought to rely on the cooperation of multiple metals in breaking the strong N≡N triple bond and forming an N–H bond. This has spurred investigations of the reactivity of molecular multimetallic hydrides with dinitrogen. We report here the reaction of a trinuclear titanium polyhydride complex with dinitrogen, which induces dinitrogen cleavage and partial hydrogenation at ambient temperature and pressure. By 1H and 15N nuclear magnetic resonance, x-ray crystallographic, and computational studies of some key reaction steps and products, we have determined that the dinitrogen (N2) reduction proceeds sequentially through scission of a N2 molecule bonded to three Ti atoms in a μ-η1:η2:η2-end-on-side-on fashion to give a μ2-N/μ3-N dinitrido species, followed by intramolecular hydrogen migration from Ti to the μ2-N nitrido unit.

Direct Characterization of Kerogen by X-ray and Solid-State13C Nuclear Magnetic Resonance Methods

2007 ◽  
Vol 21 (3) ◽  
pp. 1548-1561 ◽  
Author(s):  
S. R. Kelemen ◽  
M. Afeworki ◽  
M. L. Gorbaty ◽  
M. Sansone ◽  
P. J. Kwiatek ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
X Ray ◽  
Nuclear Magnetic

X-Ray crystallographic and 13C nuclear magnetic resonance studies of 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones derived from ephedrine and pseudoephedrine

Tetrahedron ◽  
2001 ◽  
Vol 57 (49) ◽  
pp. 9789-9798 ◽  
Author(s):  
Shawn R Hitchcock ◽  
George P Nora ◽  
David M Casper ◽  
Michael D Squire ◽  
Christopher D Maroules ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

Étude conformationnelle de cétopipérazines: (I) 3R-méthyl-6-carbéthoxy-2 oxopipérazine, (II) 3R-[p-hydroxybenzyl]-6-carbéthoxy-2 oxopipérazine: I, II en solution et structure cristalline de II

1987 ◽  
Vol 65 (6) ◽  
pp. 1308-1312 ◽  
Author(s):  
André Michel ◽  
Guy Evrard ◽  
B. Norberg
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Structure Determination ◽  
Opiate Receptor ◽  
Receptor Level ◽  
X Ray ◽  
Diastereomeric Mixture ◽  
The Absolute

The synthesis of the title compounds has been described recently. It was anticipated that the product would be a diastereomeric mixture. Surprisingly, only one isomer was obtained. The present work is an attempt to find the conformationnal properties accounting for those observations. X-ray structure determination of 3R-[p-hydroxybenzyl]-6-carbethoxy-2-oxopiperazine shows that the molecule adopts a folded conformation and that the absolute configuration at C6 is [R]. Investigation in solution using 1H nuclear magnetic resonance shows the existence of three conformers and discusses the relative populations. Those findings are also relevant in terms of the activity of such compounds at the opiate receptor level.

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