Insight into the Correlation between Net Topology and Ligand Coordination Mode in New Lanthanide MOFs Heterogeneous Catalysts: A Theoretical and Experimental Approach

Three new families of compounds were obtained as pure phases, with different lanthanide cations and the 3,5-disulfobenzoic acid (3,5-DSB). The hydrothermal synthesis conditions' influence on structural type obtained was studied. The structural type RPF-21 corresponds to the compound [Ln(3,5-DSB)(H2O)(5)] (Ln = La, Pr, Nd); RPF-22 to the compound [Ln(3,5-DSB)(H2O)(3)] (Ln = La, Pr, Nd, Sm, and Eu), and RPF-23 to the compound [Ln(3)(3,5-DSB)(2)(OH)(3)(H2O)(3)] (Ln = Pr, Nd, and Eu). The dimensionality and the topology of the compounds are determined by the sulfonate group coordination modes; RPF-23 presents a new type of topology. Computational studies have determined the relative energies for those compounds that coexist under certain hydrothermal conditions, and they have brought some light to the thermodynamic or kinetic control that drives each reaction. The new materials were tested as catalysts in cyanosilylation reaction (CSR) of aldehydes under solvent free conditions. The three of them catalyze the CSRs within 4 h, and a remarkable difference in activity is found between RPF-21 and the Other two materials. The catalytic activity mainly depends on the network structure, with very little influence of the lanthanide cation. The mechanism includes, probably, a displacement of the catalyst labile water molecules by aldehyde before catalyst's activation and reaction.