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Rationalizing the different products in the reaction of N2 with three-coordinate MoL3 complexes


Christian, G and Stranger, R and Yates, BF and Cummins, CC, Rationalizing the different products in the reaction of N2 with three-coordinate MoL3 complexes, Dalton Transactions, 2007, (19) pp. 1939-1947. ISSN 1477-9226 (2007) [Refereed Article]

DOI: doi:10.1039/b701050h


The reaction of N2 with three-coordinate MoL3 complexes is known to give rise to different products, N-MoL3, L 3Mo-N-MoL3 or Mo2L6, depending on the nature of the ligand L. The energetics of the different reaction pathways are compared for L = NH2, NMe2, N(iPr)Ar and N(tBu)Ar (Ar = 3,5-C6H3Me2) using density functional methods in order to rationalize the experimental results. Overall, the exothermicity of each reaction pathway decreases as the ligand size increases, largely due to the increased steric crowding in the products compared to reactants. In the absence of steric strain, the formation of the metal-metal bonded dimer, Mo2L6, is the most exothermic pathway but this reaction shows the greatest sensitivity to ligand size varying from significantly exothermic, -403 kJ mol-1 for L = NMe2, to endothermic, +78 kJ mol-1 for L = N(tBu)Ar. For all four ligands, formation of N-MoL3 via cleavage of the N2 bridged dimer intermediate, L3Mo-N-N-MoL3, is strongly exothermic. However, in the presence of excess reactant MoL3, formation of the single atom-bridged complex L3Mo-N-MoL3 from N-MoL3 + MoL3 is both thermodynamically and kinetically favoured for L = NMe2 and N(iPr)Ar, in agreement with experiment. In the case of L = N(tBu)Ar, the greater steric bulk of the tBu group results in a much less exothermic reaction and a calculated barrier of 66 kJ mol-1 to formation of the L3Mo-N-MoL3 dimer. Consequently, for this ligand, the energetically and kinetically favoured product, consistent with the experimental data, is the nitride complex L3Mo-N. © The Royal Society of Chemistry 2007.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Inorganic chemistry
Research Field:Transition metal chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Yates, BF (Professor Brian Yates)
ID Code:51087
Year Published:2007
Web of Science® Times Cited:16
Deposited By:Chemistry
Deposited On:2007-08-01
Last Modified:2012-03-05

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