Generation and e.s.r. spectra of some new phosphorus-centred radicals Ṗ 2 Ar 2 X, Ṗ(Ar)X, Ṗ(OAr) 2 , ṖAr 2 (:O), ṖAr[N(SiMe 3 ) 2 ](:NSiMe 3 ), and [P 2 Ar 2 ]˙ – derived from the bulky group C 6 H 2 Bu t 3 -2,4,6(= Ar)

The photochemical reaction of X2 and the diphosphene trans-ArPPar (Ar = C6H2But3), (1) leads successively to Ṗ2Ar2X, (2), Ṗ(Ar)X, (3), and upon cooling [(Ar)X]2[for X = OBut, ΔHdiss= 107 ± 7kJ mol–1] for X = OBut or SPrn, whereas for X = SBut only (3) was detected; the radicals Ṗ(Ar)X, Ṗ(Oar)2, and Ṗ2(:O) were formed by reduction of the appropriate diamagnetic PIII or PV chloride, while [P2Ar2]˙– was obtained from (1) and Na[C10H8].