Density functional study of the magneto-structural correlations of manganese complexes, [Mn2O2Hn(salpn)2]+(2−n) (n = 0–2) from the viewpoint of the protonation modes of the bridging oxygen anions

Abstract The magneto-structural correlations of [Mn 2 O 2 H n (salpn) 2 ] +(2− n ) ( n  = 0–2), for which the magnetic data were experimentally reported to strongly depend on the protonation modes, was investigated. First, the fully optimized geometries and the magnetic interactions of [Mn 2 O 2 H n (salpn) 2 ] +(2− n ) ( n  = 0–2) with using the B3LYP/LACVP ∗ method was investigated, confirming that the dependencies of the Mn–Mn distances and of magnetic interactions on the protonation mode, n ( n  = 0–2), are consistent with those experimentally reported. Further, describing the energy landscapes of both low-spin and high-spin states of these complexes for [Mn 2 O 2 ] planes, it was found that the landscapes, in particular the positions of the lines where the stable spin-state transitions occur, depend on the protonation modes of the bridging oxygen anions. Further, the details of electronic structures behind the computational results on the basis of the natural orbital analyses were discussed.