How many species do not exist?

$\begin{array}{l}{\mathrm{PH}}_3, {\mathrm{PH}}_5,{ \mathrm{PCl}}_5,{ \mathrm{PBr}}_5,{ \mathrm{SiF}}_6^{2-},{ \mathrm{SF}}_6,{ \mathrm{Al}}_2{\mathrm{F}}_6, {\mathrm{PbI}}_4,{ \mathrm{NCl}}_5,\\ {\mathrm{AlCl}}_3,{ \mathrm{OF}}_2,{\mathrm{OH}}_2,{\mathrm{OF}}_4,{ \mathrm{HFO}}_4,{ \mathrm{FeI}}_3, {\mathrm{B}}_2{\mathrm{F}}_6\end{array}$

[If your answer is 5 then write the answer as 0005.]

Since the energies of P, sp, and $d\mathit{-}$orbitals differ significantly, ${\mathrm{PH}}_5$ never form because it cannot undergo ${\mathrm{sp}}^3\mathrm{d}$hybridization.
Since N does not contain an empty d-orbital, ${\mathrm{NCl}}_5$does not exist. Therefore, it is unable to increase its octet.
As oxygen lacks a $d\mathit{-}$orbital, it cannot pass its covalency. Therefore, ${\mathrm{OF}}_4$ is not real.

The species which do not exist,

${\mathrm{PH}}_5, {\mathrm{PbI}}_4,{ \mathrm{NCl}}_5,{ \mathrm{OF}}_4,{ \mathrm{HFO}}_4,{ \mathrm{FeI}}_3,{ \mathrm{Al}}_2{\mathrm{F}}_6, {\mathrm{B}}_2{\mathrm{F}}_6$