Synthesis and Characterization of a Triphenyl-Substituted Radical and an Unprecedented Formation of a Carbene-Functionalized Quinodimethane

The trichlorosilylcarbene monoradical (Cy-cAACC center dot)SiCl3 (1) was directly converted to (Cy-cAACC center dot)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 N-14 nucleus. Functionalized 1,4-quinodimethane Me-2-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 center dot(+), as well as a radical-cation 7 center dot(+), can be prepared. Theoretical calculations showed that one-electron ionization energy and electron affinity of 7 are 5.1 and 0.7 eVmol(-1), respectively.