Direct Arc-Discharge Assisted Synthesis of C60H2(C3H5N): A cis-1-Pyrrolino C60 Fullerene Hydride with Unusual Redox Properties

Abstract

By direct arc synthesis of C60H2(C3H5N) using a modified Krätschmer−Huffman method, it is demonstrated for the first time that exohedral fullerenes with large side groups can be formed under the arc and reactive gas atmosphere conditions. The thus formed novel pyrrolino fullerene hydride was comprehensively characterized by UV−vis, infrared (IR), Raman and nuclear magnetic resonance (NMR) and studied by means of electrochemistry and in situ electron spin resonance/visible-near infrared (ESR/Vis-NIR) spectroelectrochemistry. The detailed NMR and absorption spectroscopic studies show C60H2(C3H5N) as the fullerene hydride with a pyrrolino ring attached on the vicinal position of two hydrogen atoms. This first cycloaddition adduct of C60H2 gives rise to an unusual reversible dimerization of its anion radicals and a loss of cage hydrogen atoms at the third electron transfer. The spectroelectrochemical study confirms the formation of a [C60H2(C3H5N)]− radical and the diamagnetic state of [C60H2(C3H5N)] 2−. This study reveals a unique function of a carbide structure like Al4C3 and the presence of a reactive gas atmosphere with NH3 in the formation of such an exohedral pyrrolino structure C60H2(C3H5N).