In this paper the first example of a mixed-ligand Mn II complex, having a trigonal-prismatic coordination geometry with simple, innocent, didentate ligands is presented. The solution and solid-state structures of [Mn(acac) 2 (bpy)] as studied by EPR spectroscopy, magnetic susceptibility measurements and XRD are presented: single crystals are hexagonal, space group P6 1 with unit cell dimensions a = 8.0482(9) Å, c = 51.602(10) Å, V = 2894.6(7) Å 3 and Z = 6. The complex has the trigonal-prismatic geometry only in the solid state. Density functional theory (DFT) calculations were performed to