Stabilization of O-Mn-O clusters (Mn ₅) in three dimensionally extended MOF structures: Synthesis, structure and properties

Four new three-dimensional Mn ²⁺ ion-containing compounds have been prepared by employing a hydrothermal reaction between Mn(CH ₃COO) ₂·4H ₂O, sulfodibenzoic acid (H ₂SDBA), imidazole, alkali hydroxide and water at 220 °C for 1 day. The compounds have Mn ₅ (1-4) clusters connected by SDBA, forming the three-dimensional structure. A time and temperature dependent study on the synthesis mixture revealed the formation of a one-dimensional compound, Mn(SDBA)(H ₂O) ₂, at lower temperatures (T ≤ 180 °C). The stabilization of the fcu related topology in the compounds is noteworthy. Magnetic studies indicate strong anti-ferromagnetic interactions between the Mn ²⁺ ions within the clusters in the temperature range 75-300 K. The rare participation of a sulfonyl group in the bonding is important and can pave way for the design of new structures.