Electrochemical investigations of platinum phenylethynyl complexes

We report the electrochemical characterization of a family of five platinum phenylethynyl complexes by cyclic voltammetry, bulk electrolysis, and spectroelectrochemistry. All have irreversible oxidations near +1.2 V vs. Ag∣AgCl. None has any reductive electrochemistry within the potential window of 50/50 benzene + acetonitrile. trans-Bis(tri-n-butylphosphine)bis(phenylethynyl)platinum(II) undergoes reduction in THF at −2.786 V vs. Ag∣AgCl. The number of electrons passed during the oxidation ranges from 1.15 to 2.29. Photophysical measurements show that as the phenylethynyl chain length increases, the absorbance wavelength increases and the emission wavelength shows a weak but similar trend. Spectroelectrochemistry illustrates the loss of the absorbance band over successive oxidative sweeps. Results indicate that the oxidation takes place at the Pt(II) center and is followed by chemical reactions that generate a new species.