Radical reactions in the co‐ordination sphere of transition metals. X—radicals derived from 4,4‐biphenyldiols, 4,4′‐thiobisphenols and bis(4‐hydroxybenzyl)sulphide

Using the analysis of the splitting constants of the ESR spectra, factor are described which affect the stability of free phenoxyls and of phenoxyls co‐ordinated on cobalt, generated by the reaction of tert‐butyleperoxyls and 4,4′‐biphenyldiols (1), 4,4′–thiobisphenols (2 and 5), 4,4′‐dithiobisphenol 3a, the 4,4′‐trithiobisphenol 3b, di(3,5‐di‐tert‐butyl‐4‐hydroxybenzyl) sulphide (4a) and its corresponding sulphoné (4b). Phenoxy radicals are formed from compounds of type 1–4 in the presence and in the absence of oxygen. In the case of generation with oxygem complexed to cobalt, compounds 4, for steric reasons, form co‐ordinated radicals of the cyclohexadienonyloxyl type. Free phenoxyls are also formed from 2a–2c, 3a and 3b as a result of the direct transfer of electrons from the sulphur non‐bonding electron pair to the peroxidic bond of tert‐butyl hydroperoxide in the absence of cobalt.