A Thermally Populated Germylene‐Based Donor‐Acceptor Diradical

This work reports synthesis of a germylene based donor‐acceptor molecule and its thermal excitation to a triplet state by coordination with a Lewis acid. Products have been characterized by single crystal X‐ray diffraction, EPR spectroscopy, and SQUID measurement, in conjunction with DFT calculation. The singlet‐triplet energy gap of the donor‐acceptor molecule is dramatically reduced from −18.8 to −7.2 kcal/mol by the coordination with B(C6F5)3 (BCF), which enables an intramolecular single electron transfer from one germylene moiety to another upon heating, forming an intramolecular radical ion pair with diradical character. The work provides an approach to the formation of thermally populated open‐shell species of heavier main group elements. A germylene‐based D−A molecule was synthesized by radical head‐to‐tail dimerization under mild conditions. The coordination of Lewis acids led to intramolecular single electron transfer upon heating to form a thermally populated triplet diradical. This work provided an approach to the formation of thermally populated open‐shell species in main group chemistry.