Wei, Y.; E. T. Nienhuis; S. T. Mergelsberg; T. R. Graham; Q. Guo, G. K. Schenter; C. I. Pearce; A.E. Clark. Cation Coordination Polyhedra Lead to Multiple Lengthscale Organization in Aqueous Electrolytes. Chem. Commun. 2023. 59 (69), 10400-10403. DOI: 10.1039/D3CC02416D
Understanding multiple lengthscale correlations in the pair distribution functions (PDFs) of aq. electrolytes is a persistent challenge. Here, the coordination chemistry of polyoxoanions supports an ion-network of cation-coordination polyhedra in NaNO3(aq) and NaNO2(aq) that induce long-range solution structure. Oxygen correlations associated with Na+-coordination polyhedra have two characteristics lengthscales; 3.5–5.5 Å and 5.5–7.5 Å, the latter solely associated oligomers. The PDF contraction between 5.5–7.5 Å observed in many electrolytes is attributed to the distinct O⋯O correlation found in dimers and dimer subunits within oligomers.