Question

Write IUPAC names of the following compounds : \[ (i)\ [PtCl_2(en)_2]SO_4 \] \[ (ii)\ (NH_4)_2[CoF_4] \]

Hint:

For anionic complexes, the metal name ends with ``-ate'' such as ferrate, cuprate, cobaltate, nickelate, etc.

Answer 1

Step 1: IUPAC name of $[\text{PtCl}_2(\text{en})_2]\text{SO}_4$.
$\text{SO}_4^{2-}$ outside the bracket means the complex cation has $+2$ charge. Ligands: 2 Cl$^-$ ($-1$ each) and 2 neutral en. So $x + 2(-1) = +2$, giving Pt $= +4$. Named alphabetically: dichlorido before bis(ethane-1,2-diamine). Full name: Dichloridobis(ethane-1,2-diamine)platinum(IV) sulfate.
Step 2: IUPAC name of $(\text{NH}_4)_2[\text{CoF}_4]$.
Two $\text{NH}_4^+$ cations mean the complex anion has $-2$ charge. Ligands: 4 F$^-$ ($-1$ each). So $x + 4(-1) = -2$, giving Co $= +2$. Anionic complex takes the -ate suffix: cobaltate. Full name: Ammonium tetrafluoridocobaltate(II).
Step 3: Key naming rules applied.
(i) Ligands named alphabetically before the metal. (ii) Anionic complexes use the -ate suffix for the metal name. (iii) Oxidation state in Roman numerals in parentheses after the metal. (iv) Cation is named before the complex anion.