Reaction of naphthalenedithiadiphosphetanedisulphide with ethylene glycol

Reaction of the title compounds (molar ratio 1:30) in refluxing toluene results in cleavage of one of the P-S-P bridges in naphthalenedithiadiphosphetanedisulphide 1 and formation of a new heterocycle 2 which contains a C3P2S ring with the phosphorus atoms substituted by OCH2CH2OH groups; reaction at 140 degrees C results in complete desulphuration of napthalenedithiadiphosphetanedisulphide 1 and formation of the new heterocycle 1,8-naphthodiphosphonic acid anhydride 3 which contains a C3P2O ring. 2 and 3 were characterised by microanalysis, IX, P-31 NMR and X-ray crystallography: 2, monoclinic, space group C2/c with a = 17.564(4), b = 12.475(2) and C = 16.423(3) Angstrom, beta = 102.98(3), calculated density 1.54 g/cm(3), Z = 8, reflections collected 1089, final R value 0.0501; 3, monoclinic, space group P2(1/c), with a = 7.961(2), b = 8.275(2) and c = 16.192(5) Angstrom, beta = 96.93(3), calculated density 1.694 g/cm(3), Z = 4, reflections collected 1837, final R value 0.044. No reaction occurred when 3 was heated with H2O.