Theoretical calculations are performed to study Cr2On- (n = 4 - 6) clusters. The sequential oxidation of these clusters tends to quench the spin configuration of the ground state. For Cr2O6-, the bonding orbitals dominate the higher valence molecular orbitals leading to a very high value of electron detachment energy for the cluster. Calculations also find the symmetric and asymmetric stretching of the terminal Cr-O bonds to be associated with the high frequency region of the vibrational spectrum of these clusters. Analysis of Mulliken charges and atomic spin density reveals two Cr atoms to be chemically equivalent but magnetically inequivalent atoms in these clusters. (C) 2004 Elsevier B.V. All rights reserved.