Synthesis, Photochemistry, and Electrochemistry of (P)Ge(R)₂And (P)Ge(R)X (P = TPP Or OEP, R = CH₃, CH₂C₆H₅, Or C₆H₅, and X = C1- OH- Or C104-)

The synthesis and characterization of (P)Ge(R)₂and (P)Ge(R)X, where P is the dianion of octaethylporphyrin (OEP) or the dianion of tetraphenylporphyrin (TPP), R is CH₃, CH₂C₆H₅, or C₆H₅, and X is C10₄“, CI, or 0H,- is described. Each complex was characterized by 1H NMR, IR, and UV-visible spectroscopy and electrochemistry. The investigated (P)Ge(R)₂complexes can be reduced and oxidized by up to two electrons. The reductions are reversible but a rapid cleavage of the germanium-carbon bond follows the initial electrooxidation. The final oxidation product after the abstraction of one electron from (P)Ge(R)₂was identified as (P)Ge(R)X, where X = C10₄“, Cl~, or OH- depending on the solvent/supporting electrolyte system. (P)Ge(R)Cl could also be generated from (P)Ge(R)₂in solutions of degassed CHC1₃by illumination with visible light. Electrochemical oxidation of (OEP)Ge(C₆H₅)₂, (OEP)Ge(C₆H₅)OH, and (OEP)Ge(C₆H₅)Cl gives the same final species which was spectroscopically and electrochemically identified as (0EP)Ge(C₆H₅)C10₄. Interestingly, (OEP)Ge(C₆H₅)C10₄could be converted to (OEP)Ge(C₆H₅)OH by a one-electron electroreduction which was followed by reaction of the generated anion radical with trace H₂0 in solution. Finally, an overall scheme for the oxidation and reduction of (P)Ge(R)₂and (P)Ge(R)X porphyrins is presented.