The nucleophilicity of both ortho- and meta-nitrophenolate anions is strong enough to give substituted products, but their basicity also facilitates cage-rearrangement reactions in polyhedral oligomeric silsesquioxanes (POSS). Anions having a stronger basicity, but weaker nucleophilicity, such as CO₃²⁻, gave products only from cage-rearrangement, with the cage expansion products being isolable in multi-gram quantities using conventional column chromatography.