SYNTHESIS, SPECTROSCOPIC STUDIES AND STRUCTURAL CHARACTERIZATION OF SOME NEW 2-(PHOSPHONIOARYL)IMIDAZOLIDE BETAINES

The synthesis is described of three series of 2-(phosphonioaryl)(benz) imidazolide betaines, viz (i) the 2-(2-or 3-or 4-tributylphosphoniophe nyl)benzimidazoli (ii) the 2-(2-and osphoniophenyl)-1H-phenanthro[9,10 -d]imidazolides, and (iii) the 2-(2-and rganophosphoniophenyl)-4,5-dip henyl-immidazolides. A detailed H-1, C-13 and P-31 NMR study of the 2- (tributylphosphoniophenyl)benzimidazolides reveals significant differe nces in the spectroscopic parameters of the betaines compared with tho se of the phosphonium salts from which they are derived. Full X-ray st ructural studies are reported for 2-(4-triphenylphosphoniophenyl)-1 H- phenanthro[9, 10-d]imidazol-1-ide and henylphosphoniophenyl)-4,5-diphe nylimidazol-1-ide, and comparisons made with related pyridiniumimidazo lide systems. The phosphonioimidazolide betaines exhibit negative solv atochromism.