Beta-nitro derivatives of germanium(IV) corrolates.

The reaction between germanium(IV) meso-triphenylcorrolates and nitrate salts affords the corresponding beta-nitro substituted corroles in good yield. Chromatographic separation of the crude reaction mixtures enables isolation of a mu-oxo dimer along with the corresponding monomers bearing a hydroxy or methoxy group at an axial position of the germanium central metal ion. Depending on the reaction conditions, mono- or dinitro substituted complexes can be obtained. The substitution is highly regioselective in each case, giving only the 3-nitro or 3,17-dinitro derivative among the different possible isomers. Five of the synthesized complexes were examined by cyclic voltammetry and UV-visible spectroelectrochemistry in dichloromethane, and the dinitro mu-oxo dimer is structurally characterized.