Synthesis and characterization of antimony(V)-oxo corrole complexes

Abstract

Two corrolato-antimony(III) complexes have been prepared for the first time and characterized by a series of spectroscopic techniques. Both the complexes have been oxidized by iodosobenzene and the corresponding oxidized derivatives have been isolated and thoroughly characterized. All the four antimony complexes, including two corrolato-antimony(III) complexes and two (corrolato)(oxo)antimony(V) complexes are diamagnetic in nature as is evident from their “normal” chemical shifts. For one of the structurally characterized corrolato-antimony(III) complexes, we have obtained two different conformers in two different solvents with slightly different bond lengths and angles. SbIII corroles are dome shaped and the deviation of SbIII ion with respect to the plane consisting four pyrrolic nitrogen atoms is ~0.963–0.966 Å. The two corrolato-antimony(III) complexes exhibited split Soret bands in the range of 440–462 nm due to the low symmetric nature of these molecules. The two (corrolato)(oxo)antimony(V) complexes exhibited single Soret band in the range of 408–413 nm. All the four antimony complexes displayed weak emission in the range of 630–650 nm and a shoulder at 690–710 nm in CH2Cl2. These emission bands are assigned as fluorescence bands due to the observation of smaller Stokes shift in reference to the lowest energy Q-type bands.