| Abstract
| - 2,3,5,6-Tetrafluorophenylnitren-4-yl (5) was synthesized in argon at 4 K via the photolysis of2,3,5,6-tetrafluoro-4-iodo-phenyl azide (6). Electron paramagnetic resonance (EPR) spectroscopy allowsus to observe triradical 5 in its quartet state with the zero-field splitting (ZFS) parameters |D/hc| = 0.285and |E/hc| = 0.043 cm-1. The quartet ground state of 5 is in accordance with our previous infrared (IR)spectroscopic investigation, in which the high-spin quartet state, but no low-spin doublet state, of 5 wasobserved in solid argon at 4 K [Wenk, H. H.; Sander, W. Angew. Chem., Int. Ed.2002, 41, 2742−2745].Because annealing of the matrix at temperatures of >10 K results in the rapid recombination of the highlyreactive species 5 with I atoms produced during the photolysis of 6, the Curie−Weiss behavior could notbe investigated. However, the absence of low-spin states in the IR investigations, as well as the results ofab initio and density functional theory (DFT) calculations, strongly suggest that 5 has a robust quartetground state that is best-described as an unprecedented σ,σ,π-triradical. The ZFS of 5 has been successfullyreproduced by DFT calculations, which furthermore provide qualitative insight into the origin of the observedEPR parameters.
|
