Metalation of 6,13,20,21-tetraaryl-22H-tribenzotriphyrins( 2.1.1) (TriP, 1a-d ) with [Mn(CO)5Br] provided MnI tricarbonyl complexes of tribenzotriphyrins(2.1.1) 2a-d in 85-93% yield. The complexes were characterized by mass spectrometry and UV/Vis absorption, IR, and NMR spectroscopy. Single-crystal X-ray analyses revealed that 2b and 2c adopt bowl-shaped conformations. The redox properties of [(TriP)MnI(CO)3] (2a -d) were studied by cyclic voltammetry. Each compound undergoes two reversible one-electron reductions to form a porphyrin p anion radical and a dianion in CH2Cl2. Two oxidation waves were observed, the first of which corresponds to a metal-centered electron-transfer process. The redox potentials of 2a-d are consistent with the optical spectroscopic data and the relatively narrow HOMO-LUMO gaps that were predicted in DFT calculations. The optical spectra can be assigned by using Michl's perimeter model. TDDFT calculations predict the presence of several metal-to-ligand charge-transfer bands in the L-band region between 500 and 700 nm.
- Circular dichroism
- Density functional calculations
ASJC Scopus subject areas
- Organic Chemistry