Magnetic resonance studies of solutions containing 115In

Abstract

N.m.r. linewidth studies are described for ¹¹⁵In in aqueous solutions of the nitrate and sulphate. Because it has a large nuclear electric quadrupole moment, ¹¹⁵In has short relaxation times and the effects on these of (a) viscosity and (b) symmetry of molecular environment, are investigated. Hydrolysis at low concentrations increases the linewidth, and in the nitrate solutions, but not the sulphate, weak complex formation increases linewidth at high concentrations. Chemical shift data also support this interpretation.

Complexes are formed in indium halide solutions and exchange rates for In³⁺+ InX²⁺⇌ InX²⁺+ In³⁺ are calculated by the exchange broadening of the ¹¹⁵In line on adding small amounts of halide to In(ClO₄)₃ solutions. A similar calculation is made for the InCI^–₄/CI^– exchange. The resonances of the species InX^–₄(X = Cl,Br,I) in ethereal solution are described and a table of linewidths and shifts given. In conc. aqueous HCl and HBr other less symmetrical species are present.