Ion‐Association Reaction Involving Anionic Complexes of Arsenic ( III and V) by Monocationic Surfactant

Stable and unstable transition metal coordination compounds are well known. Here we have discussed ion‐association (I‐A) reactions involving Bjerrum's proposition and then differentiate thermodynamic stability and instability from kinetic (inert and labile) factors in reference to coordination complexes of metalloid arsenic (III) and (V). So, one representative square planar sodium salt of anionic catecholate, [Na] + [As III (cat) 2 ] −1 ( K = 1.65 ± 0.17 × 10 4 ) and one representative octahedral sodium catecholate, [Na] + [As V (cat) 3 ] −1 (K = 1.06 ± 0.22 × 10 5 ) are produced from grinding mixing protocol (GMP). Then the substitution reaction of both complex sodium salts, [Na] + [As III (cat) 2 ] −1 and [Na] + [As V (cat) 3 ] −1 are accomplished using cationic surfactant cetyltrimethylammonium bromide (CTAB) and a cationic dye methylene blue (MB) in aqueous solution. All the substitution reactions have been observed to be facile in water as well as in toluene in spite of the change of solvent dielectric behavior. Subsequently, it is found that [CTA] + and [MB] + substitute [Na] + in both the solvents. However, the surfactant CTAB substituted 1:1 colorless I‐A, i.e., [CTA] + [As(cat) 2 or 3 ] −1 does not support substitution by methylene blue.