ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P108. Oxidation of Nitrite by a trans-Dioxoruthenium(VI) Complex.
Direct Evidence for Reversible Oxygen Atom Transfer
T. Ch. Lau
Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Hong Kong, China
e-mail:bhtclau@cityu.edu.hk
The inter-conversion between nitrite and nitrate is of fundamental interest and of biological importance. Reaction
of trans-[RuVI(L)(O)2] 2+ (1, L = 1, 12-dimethyl-3, 4:9, 10-dibenzo-1, 12-diaza-5, 8- dioxacyclopentadecane, a
tetradentate macrocyclic ligand with N2O2 donor atoms) with nitrite in aqueous solution or in H 2 O/CH 3 CN
produces the corresponding (nitrato)oxoruthenium(IV) species, trans-[RuIV(L)(O)(ONO2)] + (2), which then
undergoes relatively slow aquation to give trans-[RuIV(L)(O)(OH2)] 2+ . These processes have been monitored by
both ESI/MS and UV/Vis spectrophotometry. The structure of trans-[RuIV(L)(O)(ONO2)] + (2) has been
determined by X-ray crystallography. The ruthenium center adopts a distorted octahedral geometry with the oxo
and the nitrato ligands trans to each other. The Ru=O distance is 1.735(3) Å, the Ru-ONO2 distance is 2.163(4)
Å and the Ru-O-NO2 angle is 138.46(35)°. Reaction of trans-[RuVI(L)(18O)2] 2+ (1-18O2) with N16O2- in
H2O/CH3CN produces the 18O-enriched (nitrato)oxoruthenium(IV) species 2-18O2. Analysis of the ESI/MS
spectrum of 2-18O2 suggests that scrambling of the 18O atoms has occurred. A mechanism that involves linkage
isomerization of the nitrato ligand and reversible oxygen atom transfer is proposed.Financial support by the
Research Grants Council of Hong Kong (CityU 1105/02P and CityU 2/06C) is gratefully acknowledged.
References:
[1] W. L. Man, W. W. Y. Lam, W. Y. Wong, T. C. Lau J. Am. Chem. Soc. 2006, 128, 14669-14675.
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