The activation and scission of the N-O bond in nitric oxide using dinuclear mixed-metal species, comprising transition elements with d3 and d2 configurations and trisamide ligand systems, have been investigated by means of density functional calculations. The [Cr(iii)-V(iii)] system is analyzed in detail and, for comparative purposes, the [Mo(iii)-Nb(iii)], [W(iii)-Ta(iii)], and (mixed-row) [Mo(iii)-V(iii)] systems are also considered. The overall reaction and individual intermediate steps are favourable for all systems, including the case where first row (Cr and V) metals are exclusively involved, a result that has not been observed for the related dinitrogen and carbon monoxide systems. In contrast to the cleavage of dinitrogen by three-coordinate Mo amide complexes where the dinuclear intermediate possesses a linear [Mo-NN-Mo] core, the [M-NO-M′] core must undergo significant bending in order to stabilize the dinuclear species sufficiently for the reaction to proceed beyond the formation of the nitrosyl encounter complex. A comparative bonding analysis of nitric oxide, dinitrogen and carbon monoxide activation is also presented. The overall results indicate that the π interactions are the dominant factor in the bonding across the [M-L1L2-M′] (L1L2 = N-O, N-N, C-O) moiety and, consequently, the activation of the L1-L2 bond. These trends arise from the fact that the energy gaps between the π orbitals on the metal and small molecule fragments are much more favourable than for the corresponding σ orbitals. The π energy gaps decrease in the order [NO < N2 < CO] and consequently, for each individual π orbital interaction, the back donation between the metal and small molecule increases in the order [CO < N2 < NO]. These results are in accord with previous findings suggesting that optimization of the π interactions plays a central role in increasing the ability of these transition metal systems to activate and cleave small molecule bonds. © The Royal Society of Chemistry 2009.

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:	62449
Year Published:	2009
Funding Support:	Australian Research Council (DP0986529)
Web of Science® Times Cited:	11
Deposited By:	Chemistry
Deposited On:	2010-03-12
Last Modified:	2012-03-05
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