Synthesis and Characterization of Diiron(II) Complex with the Asymmetric Ligand Fixed into Internal Surface of Mesoporous Silica

摘要

A new diferrous complex with asymmetric coordination sites, [Fe_2(μ-OBz)(L)](ClO_4)_2 (1) (L = N,N-bis(6-methyl-2-pyridylmethyl)-A',N'-bis(6-pivalamido-2-pyridylmethyl)-1,3-diamino-propan-2-ol), was synthesized, which was immobilized in the internal surface of mesoporous silica (FSM-16) to construct a functional material (1A). The reaction of 1 with O_2 in acetone at -50°C generated a peroxo complex 2 [λ_(max) = 589nm (ε = 2200 M~(-1) cm~(-1)), v~(16)O-~(16)O = 890 and 908 cm~(-1) (v~(18)0-~(18)O = 852 cm~(-1))]. The μ-peroxo complex 2 was decomposed by bubbling of Ar gas without releasing O_2, but the reaction of 1A with O_2 at ambient temperature also formed a peroxo complex (2A) without decomposition. The reflectance spectrum of 2A showed a band assignable to the LMCT band from peroxo to a Fe(III) ion at 588 nm. Compound 2A is very stable, whose half-life time is 45 min, in contrast to a short life of 2 (310 sec). 2A released dioxygen by heating up to 75°C in vacuo, which was regenerated by bubbling of dioxygen at ambient temperature.