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On the Origin of Dinitrogen Hydrogenation Promoted by [(η⁵-C₅Me₄H)₂Zr]₂(μ₂,η²,η²-N₂)

Supporting Info

Jaime A. Pool, Wesley H. Bernskoetter, and Paul J. Chirik*

Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853

J. Am. Chem. Soc., 2004, 126 (44), pp 14326–14327

DOI: 10.1021/ja045566s

Publication Date (Web): October 19, 2004

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, pc92@cornell.edu

Abstract

The origin of the hydrogenation of the dinitrogen ligand in [(η⁵-C₅Me₄H)₂Zr]₂(μ₂,η²,η²-N₂) has been investigated by a combined computational and experimental study. Density functional theory calculations on the zirconocene dinitrogen complex demonstrate significant imido character in the zirconium nitrogen bonds, arising from effective π-back-bonding from the low-valent zirconium and the side-on bound N₂ ligand. The twisted ground-state structure of the N₂ complex is a key requirement for nitrogen hydrogenation, as calculations on the model complex [(η⁵-C₅H₅)₂Zr]₂(μ₂,η²,η²-N₂) reveal reduced overlap as the dihedral angle between the zirconocene wedges approaches 0°. Experimentally, isotopic labeling studies on the microscopic reverse are consistent with a 1,2-addition mechanism for nitrogen hydrogenation.

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Published In Issue November 10, 2004
Received July 23, 2004

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Communication

On the Origin of Dinitrogen Hydrogenation Promoted by [(η⁵-C₅Me₄H)₂Zr]₂(μ₂,η²,η²-N₂)