Other solvents
Good donor ability and hydrogen bonding ability (that contributes to the solvation of anions) water is one of the best solvents with its combination of high dielectric constant, for ionic substances. Two another solvents of comparable polarity are H2SO4 and HF. Solubility trends for metal fluorides in HF depict close parallels with those for oxides and hydroxides in water. So they follow the sequence MF>MF2>MF3, and for a specific charge the solubility tends to increase with the cation size.
As the dielectric constant reduces, the solvation energies become less capable to compensate for the lattice energy. This is particularly right for solids with multiply charged ions, and such types of compounds are much less soluble in liquid ammonia than soluble in water. Comprehensive comparisons are complicated, though, by the occurrence of ion pairing, and by the increased significance of another interactions. Ammonia is a better donor than the water for soft class b cations like Ag+ (see Topic E3) and compounds like AgCl are much more soluble. In ammonia the solubility trend AgI>AgBr >AgCl is also the opposite of that found in water, reflecting other difference: ammonia has a larger polarizability than water and so van der Waals' forces are more significant. They contribute considerably to the solvation of heavier anions like I-. Some iodides like LiI are soluble in solvents of low polarity, a fact that is sometimes incorrectly employed to suggest that the solids have appreciable covalent character. Actually, LiI frequently dissolves as an ion pair, the donor solvent coordinating Li+ and the van der Waals' forces solvating I-.