New Manganese Complexes Showing Axially-Compressed Octahedral Geometry: Structure and Magnetic Properties

The straightforward combination of commercial picolinaldehyde and 2-aminopyridine led to the preparation of N,1-di(pyridin-2-yl)methanimine ligand HL1. Under aerobic conditions, HL1 self-assembles with manganese (Mn) ions to afford two high-spin mononuclear Mn(III) complexes of general formula [MnL22]+Cl (1) and [MnL22]+(NO3) (2). Their synthesis is mediated via (in situ) ligand transformation and oxidation of initial Mn(II) ions. Such unexpected reorganization contributes in the stabilization of the complexes. The mononuclear compounds 1 and 2 display unusual Jahn-Teller distortion along the z-axis, as evidenced by single-crystal X-ray diffraction and do exhibit an S = 2 ground spin state.