Study of the light-induced spin crossover process of the [Fe(II)(bpy)3]2+ complex.
Ab initio calculations have been performed on [Fe(II)(bpy)3](2+) (bpy = bipyridine) to establish the variation of the energy of the electronic states relevant to light-induced excited-state spin trapping as a function of the Fe-ligand distance. Light-induced spin crossover takes place after excitation into the singlet metal-to-ligand charge-transfer (MLCT) band. We found that the corresponding electronic states have their energy minimum in the same region as the low-spin (LS) state and that the energy dependence of the triplet MLCT states are nearly identical to the (1) MLCT states. The high-spin (HS) state is found to cross the MLCT band near the equilibrium geometry of the MLCT states. These findings give additional support to the hypothesis of a fast singlet-triplet interconversion in the MLCT manifold, followed by a (3)MLCT-HS ((5)T2) conversion accompanied by an elongation of the Fe-N distance.
Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, c/Marcel⋅lí Domingo s/n, Campus Sescelades, 43007 Tarragona (Spain), Fax: (+34) 977-55-9563; Institució Catalana de Recerca i Estudis Avançcats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona (Spain). coen.degraaf@urv.cat.
Coen
C
de Graaf
Carmen
C
Sousa
ab initio calculations; magnetic properties; photochemistry; spin crossover; transition metals