THE REACTION OF CARBOLIC ACIDS WITH TETRA PHOSPHA TRICHALCOGENA DIIODIDES IN CS2 SOLUTION

alpha-P4E3(I)R and alpha-P4E3R2 (E = S and/or Se) have been identified by P-31 n.m.r. spectroscopy in reaction solutions of alpha-P4E3I2 and carbolic acids with pK(s) values 23 in presence of triethylamin. Simi lar products were obtained in comparable yields with carbolic acids, h aving pK(s) values <3, only by the reaction with their tin organic der ivates. The chemical shifts of the ligand carrying phosphorus atoms ar e depending on the electronegativity of oxygen, in addition to the ind uctive effect of the organic group connected to the carboxyl group. Ch emical shifts and coupling constants of alpha-P4E3(I)R can be calculat ed from the symmetric compound alpha-P4E3I2 and alpha-P4E3R2. Deviatio ns between calculated and measured values of side and bridge coupling constants indicate a torsion of the molecular skeleton due to the larg e size difference between the two ligands. An endocyclic replace ment of sulfur by selenium in alpha-P4S3R2 revealed significant differences in the behaviour of the side couplings, as compared with alpha-P4SnSe 3-nI2, which are probably due to an interaction of the carboxyl ligand with its chalcogen neighbour.