Six-Coordinate Nitrato Complexes of Iron(III) Porphyrins

The interaction of tetrahydrofuran (THF) with thin films of the nitrato
complexes FeIII(Por)(η2-O2NO) [Por = meso-tetraphenylporphyrinato (TPP) and meso-tetratolylporphyrinato (TTP) dianion] at low
temperature leads to the formation of the six-coordinate nitrato
complex Fe(Por)(THF)(NO3), which was characterized by IR and
UV−visible spectroscopies. Formation of the THF adduct was
accompanied by nitrate linkage isomerization from bidentate to
monodentate coordination. The iron(III) center remains in a high
spin state in contrast with the previously observed low-spin
nitratonitrosyl complex Fe(TPP)(NO)(η1-ONO2). Upon warming,
THF dissociates to restore the initial five-coordinate bidentate nitrato
complex.