Solid-state lattice effects on high-spin Mn(III) complexes with hexadentate Schiff-base ligand

ABSTRACT This paper reports the syntheses, crystal structures, magnetics and spectroscopic properties of high-spin (HS) salts of formula [Mn(salk-N-1,5,8,12)]Y·S (Y = AsF6 for 1, Y = BF4, S = CH3OH for 2, Y = PF6, S = CH3OH for 3), where (salk-N-1,5,8,12)2− (2,2ʹ-((2E,14E)-3,7,10,14-tetraazahexadeca-2,14-diene-2,15-diyl)diphenolate) is a hexadentate Schiff-base ligand. Crystal structural analysis indicates that the extensive hydrogen bonds play a primary role in stabilisation of their HS states. As an aid to understanding this behaviour, the crystal structure of the known spin crossover compound [Mn(sal-N-1,5,8,12)]AsF6 (4) has been re-examined. To understand the impact of intermolecular forces to the different magnetic behaviours of salts 1 and 4, we evaluate of their supramolecular structures and confirm that intermolecular interactions can significantly affect the cooperativity. Furthermore, electrochemical studies on 1 and 4 shows that the choice of spin state is controlled by the solid-state lattice effects, i.e. cooperativity rather than molecular electronic effect. Graphical abstract