Buffering additive effect in the formation of metal–carboxylate frameworks with slightly different linear M3(RCOO)6 clusters

By treating M(NO3)2 or MCl2 (M = Mn, Fe, Co and Ni) with 2,6-naphthalene dicarboxylic acid (ndcH2), a series of metal–carboxylate frameworks have been solvothermally synthesized under the same route with different buffering anions, which feature two kinds of frameworks based on slightly different linear M3(OOCR)6 secondary building units: [M3(ndc)3(DMF)4]n (M = MnII, FeII and CoII) or [M3(ndc)3(DMF)2(Me2NH)2]n (M = CoII and NiII). Consequently, the two cobalt compounds exhibit different magnetic behaviours.