D.M. and G.B. acknowledge financial support from the NSF (CHE-1112133 and CHE-1316956), and Maria Angelella and Michael Tauber for assistance with ESR experiments. D.M. acknowledges the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by NSF (OCI-1053575).
Easy does it! Simply take two carbenes, add carbon monoxide, then HCl, and open the flask to air, and an oxyallyl radical cation is formed.