The resonance Raman spectra of manganate(V) ion in aqueous solution in the
visible and near-UV regions were studied, The maximum in the Raman excitati
on profile (REP) of the totally symmetric vibrational mode (v(1)) at ca 600
nm is assigned to a charge-transfer transition with appreciable d-d charac
ter, Owing to marked orbital mixing in such systems, the observed Raman enh
ancement could also be assigned to a d-d transition with a high charge-tran
sfer character. The absence of overtones in the Raman spectrum indicates a
small shift in the equilibrium Mn-O bond distances (delta(r)) between the e
xcited and fundamental electronic states. This finding was confirmed by the
calculation of the REP within the time formalism approach. The best fitted
delta(r) value is lower than the corresponding reported values for mangana
te(VII) and manganate(VI) ions. Two models were used in the calculations, i
n which whether a single or two electronic transitions were considered in t
he visible range of the absorption spectrum. Similar delta(r) values were o
btained with both models. Copyright (C) 1999 John Wiley & Sons, Ltd.