A recently
synthesized Mn-containing molecule Ce2
IIICeIVMn8
IIIO8(O2CPh)18(HO2CPh) (Ce3Mn8
III) structurally
resembles the repeating unit of a bulk perovskite
manganite. This resemblance brings forth the intriguing possibility
of studying physical properties and effects that appear in both the
molecule and the far more complex bulk perovskites, for example, effects
of cation substitution, which in bulk manganites may lead to phase
transition from metallic-ferromagnetic to insulating-paramagnetic
as well as the colossal magnetoresistance effect. We investigate divalent
and trivalent cation substitution in Ce3Mn8
III molecules
and its effects on ground-state magnetic configuration using first-principles-based
approaches. One MnIII ion changes its valence to MnIV after trivalent (including La, Gd) cation substitution,
while four MnIII ions become MnIV upon divalent
(including Ca, Sr, Ba, and Pb) cation substitutions, all accompanied
by vanishing local Jahn–Teller distortion around MnIV. The valence state of MnIV induced by cation substitutions
can hop among Mn sites in molecule, and the calculated energy barrier
for such state hopping is 0.25 to 0.6 eV/molecule. In addition, the
charging energies of the Ce3Mn8
III molecule and its derivatives are
found to be strongly dependent on the spin direction of added electron.