TETRAARYLESTERS OF MU-IMIDO-DIPHOSPHORIC ACID AND ITS THIO DERIVATIVES - STRUCTURE INVESTIGATIONS

New O,O',O'',O'' -tetratolyl- and ditolyl-diphenyl-esters of the mu-im ido-diphosphoric acid and its mono and dithio derivatives were synthes ized, compared with the corresponding tetraphenylesters and investigat ed by H-1, C-13, and P-31 NMR spectroscopy and X-ray crystal structure analysis. Structures of the O,O',O'',O'' -tetrakis-(2-methyl-phenyl)- mu-imido-diphosphate, 1b, as well as of the corresponding ortho-, meta -and para-tolylesters of the mu-imido-monothiodiphospheric acid (2a, 2 b, 2c) were determined. All the compounds form dimers via N-H...O hydr ogen bonds in the crystal as well as in non polar solvents. The distan ces around the phosphorus atoms rise with decreasing electronegativity of the phosphorus substituents. Signs of the (2)J(P-N-P) coupling con stants were determined by C-13{H-1,P-31} triple resonance experiments for some compounds. These constants become more negative owing to subs titution of a phosphoryl by a thiophosphoryl group.