Stable Radicals from Commonly Used Precursors Trichlorosilane and Diphenylchlorophosphine
Abstract: The intermediate species dichlorosilylene was in situ generated from trichlorosilane and inserted into the P-Cl bond of diphenylchlorophosphine (Ph2P-Cl) to obtain Ph2P-SiCl3 (1). The mono-dechlorination of 1 by cyclic alkyl(amino) carbenes (cAACs)/KC8 in THF at low temperature led to the formation of the stable radicals Ph2P-Si(cAAC·)Cl2 (2a-b) which were characterized by X-ray single crystal diffraction, mass spectrometry, and studied by cyclic voltammetry and theoretical calculations. The radical properties of 2 are confirmed by EPR measurements which suggest the radical electron in 2 couples with 14N (I = 1), 35/37Cl (I = 3/2) and 31P (I = 1/2) nuclei leading to multiple hyperfine lines. Hyperfine coupling parameters computed from DFT calculations are in good agreement with those of experimental values. The electronic distributions obtained from the theoretical calculations suggest that the radical electron resides mostly on the carbene carbon of 2.