Bis(phenanthrolinyl)amine manganese complexes with pseudo-trigonal prismatic geometry

Two manganese(II) complexes supported by an isoamyl-substituted bis(phenanthrolinyl)amine ligand have been prepared and characterized. Determination of the molecular structures through X-ray crystallography demonstrated that the triflate compound crystallizes as a monomeric species with an outer-sphere anion, while the chloride complex exists as a dimer containing bridging chloride ligands in the solid state. Importantly, these structures revealed a coordination environment about the metal centre that is best described as pseudo-trigonal prismatic in both cases. Computational analysis found an optimized geometry for the triflate complex in a highspin state that is consistent with the experimental observations, while the low-spin calculation showed a significant shift toward octahedral geometry. These results and their contrast with previously reported data provide evidence for the influence of electronic structure and metal ion size on molecular geometry in this system.