Stable Radicals from Commonly Used Precursors Trichlorosilane and Diphenylchlorophosphine

Abstract

Intermediate species dichlorosilylene was generated in situ from trichlorosilane and inserted into the P-Cl bond of diphenylchlorophosphine (Ph 2 P-Cl) to obtain Ph 2 P-SiCl 3 (1). Monodechlorination of 1 by cyclic alkyl(amino) carbenes (cAACs)/KC 8 in THF at low temperature led to the formation of stable radicals Ph 2 P-Si(cAAC·)Cl 2 (2a,b). Compounds 2a,b were characterized by X-ray single crystal diffraction, mass spectrometry and studied by cyclic voltammetry and theoretical calculations. Radical properties of 2 are confirmed by EPR measurements that suggest the radical electron in 2 couples with 14 N (I = 1), 35/37 Cl (I = 3/2), and 31 P (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. Electronic distributions obtained from the theoretical calculations suggest that the radical electron mostly resides on the carbene C of 2.