Naming this iron complex: Fe2Cl6[H2O]5
In coordination chemistry square brackets denote inner coordination sphere; $\ce{[H2O]5}$ makes little sense in this context.
It looks like the correct molecular formula for this compound appears to be $\ce{[FeCl2(H2O)4]+[FeCl4]- * H2O}$ according to the crystal structure determined by Szymański [1].

The IUPAC-compliant name proposed by the author is tetraaqua-cis-dichloroiron(III) tetrachloroferrate(III) monohydrate.



Figure 1. Asymmetric unit $\ce{[FeCl2(H2O)4]+[FeCl4]- * H2O}$ (ICSD-8198) with added hydrogen atoms.
Color code: $\color{#EEEEEE}{\Large\bullet}~\ce{H}$; $\color{#FF0D0D}{\Large\bullet}~\ce{O}$; $\color{#1FF01F}{\Large\bullet}~\ce{Cl}$; $\color{#E06633}{\Large\bullet}~\ce{Fe}$.

References


Szymański, J. T. The Crystal Structure of Tetraaqua-cis-Dichloroiron(III) Tetrachloroferrate(III) Monohydrate (Ferric Chloride $2\frac 1 2$-Hydrate). Acta Cryst. B 1979, B35 (9), 1958–1963. https://doi.org/10.1107/S0567740879008244.