Table 3.

Structural parameters of hydrated tetravalent metal cations, $r_1$ and $r_2$ are the mean distances of first and second hydration shell, $N_1$ and $N_2$, the (average) number of ligands in these shells.

Ion	$r_1$ (Å)	$r_2$ (Å)	$N_1$	$N_2$	Ref.
Ce(IV)	2.44	4.7	9	17.4	[42]
Zr(IV)	2.25	4.5	8	17.8	[46]
Hf(IV)	2.26	4.5	8	17.2	[47]
U(IV)	2.46	4.8	9	17.4	[53]