Reaction of P4 with Br2 or I2, followed by treatment of product soluti
ons with halide substitution reagents, allowed the identification by N
MR of low concentrations of exo,exo-P4ClnBr2-n(1), exo,endo-P4ClnBr2-n
(2), symm-P7X3 (X = Br or 1)(3) and P2XnY4-n (X and Y = two of Cl, Br,
I).