New perthiophosphonic acid anhydrides and the direct indication of the dimer‐monomer equilibrium. NMR and X‐Ray Studies

Abstract New perthiophosphonic acid anhydrides (R‐PS 2 ) n with R = 2,4,6‐tri‐iso‐propylphenyl and 2,4‐di‐tert‐butyl‐6‐methylphenyl have been prepared. For the latter case, the isolation of the monomer (n = 1), the 2,4‐di‐tertbutyl‐6‐methylphenyl‐dithioxophosphorane, and both dimers (n = 2), cis‐ and trans‐2,4‐bis(2,4‐di‐tertbutyl‐6‐methylphenyl)‐2, 4‐dithioxo‐1, 3, 2, 4‐dithiadiphosphetane, has been determined. The new cis and trans dithiadiphosphetanes and dithioxophosphoranes as well as the known compounds (2,4,6‐trimethylphenyl‐PS 2 ) 2 and 2,4,6‐tri‐tert‐butylphenyl‐PS 2 are characterized by solution and high resolution solid‐state 31 P and 13 C NMR spectroscopy. The existence of a dimer‐monomer equilibrium is directly proved by 2D exchange 31 P NMR spectroscopy. It is shown that the reaction of the monomer with methanol is faster than the reaction of the dimer with methanol.