Characterization of Single and Pairwise No 2 Adsorption on the (Mgo) 9 and (Cao) 9 Clusters

Vibrational spectra have been computed by means of the b3lyp hybrid density functional in order to interpret the experiments [j. phys. chem. b 2002,106,6358],particularly regarding a transient 1225 cm -1 absorption during accumulation of no 2 in mgo supported bao. the degree of generality of results is tested by comparing (no 2) x(mo) 9 for x=1,2 and m=mg,ca. finger prints are produced for the single bidentate m 2+-[ono] --m 2+ surface nitrite ion,a novel single monodentate [o clus-no 2] -2 ion,and the chemisorbed nitrite/nitrate ion pair,i.e.,m 2+ - [ono] --m 2++ [o clus-no 2] -. the results suggest the novel monodentate [o clus- no 2] -2 to be responsible for the experimentally observed 1225 cm -1 absorption,being a transient towards surface nitrate rather than nitrite formation. this result is consistent with a mechanistic periodic dft study concerning the initial loading of no 2 in bao.