The invention relates to a composition comprising an organic material susceptible to oxidative, thermal or light-induced degradation and a compound of formula I-P, I-O or I-M. Further embodiments are a compound of formula I-P, I-O or I-M, a process for protection of the organic material by the compound, the use of the compound against degradation of the organic material, an additive composition comprising the compound, a process for manufacturing the compound and an intermediate involved therein.