The trichlorosilylcarbene monoradical (Cy-cAAC ·)SiCl3 (1) was directly converted to (Cy-cAAC ·)SiPh3 (2) by substitution of the three chlorine atoms with phenyl groups without affecting the radical center adjacent to the silicon atom. In addition to the structure determination, compound 2 was studied by EPR spectroscopy and DFT calculations. The three hyperfine lines in the EPR spectrum of 2 are due to the coupling with (14)N nucleus. Functionalized 1,4-quinodimethane Me2-cAAC=C6H4=CPh2 (7) was isolated, whereas carbon analogue of radical 2 was targeted. Cyclic voltammogram of 7 indicated that a stable radical-anion 7 ·-, as well as a radical-cation 7 ·+, can be prepared. Theoretical calculations showed that one-electron ionization energy and electron affinity of 7 are 5.1 and 0.7 eV mol(-1), respectively.
Keywords: EPR spectroscopy; carbenes; cyclic voltammetry; density functional calculations; radicals.
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