Crystalline Cyclic (Alkyl)(amino)carbene-tetrafluoropyridyl Radical.
A stable cyclic (alkyl)(amino)carbene (CAAC) 1 inserts into the para-CF bond of pentafluoropyridine, and after fluoride abstraction, the iminium-pyridyl adduct [3](+) was isolated. A cyclic voltammetry study shows a reversible three-state redox system involving [3](+) , [3](⋅) , and [3](-) . The CAAC-pyridyl radical [3](⋅) , obtained by reduction of [3](+) with magnesium, has been spectroscopically and crystallographically characterized. In contrast to the lack of π communication between the CAAC and the pyridine units in cation [3](+) , the unpaired electron of [3](⋅) is delocalized over an extended π system involving both heterocycles.
UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0343 (USA) http://bertrandgroup.ucsd.edu.|Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstrasse 15, 76131 Karlsruhe (Germany).
Steffen
S
Styra
UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0343 (USA) http://bertrandgroup.ucsd.edu.
Mohand
M
Melaimi
UCSD Crystallography Facility, Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0343 (USA).
Curtis E
CE
Moore
UCSD Crystallography Facility, Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0343 (USA).
Arnold L
AL
Rheingold
Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstrasse 15, 76131 Karlsruhe (Germany).
Timo
T
Augenstein
Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry, Engesserstrasse 15, 76131 Karlsruhe (Germany). breher@kit.edu.
Frank
F
Breher
UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0343 (USA) http://bertrandgroup.ucsd.edu. guybertrand@ucsd.edu.
Guy
G
Bertrand
carbenes; cyclic voltammetry; radicals; redox chemistry