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

Concept: The IUPAC nomenclature of coordination compounds involves the following steps:

• Identify the complex ion.

• Determine the oxidation state of the central metal atom.

• Name ligands alphabetically.

• Name the metal.

• Add oxidation state in Roman numerals.

• Name the counter ion.

(i) Naming of \([PtCl_2(en)_2]SO_4\)

Step 1: Determine charge on the complex ion. Sulphate ion has charge: \[ SO_4^{2-} \] Hence the complex ion must have charge: \[ +2 \]

Step 2: Calculate oxidation state of platinum. Let oxidation state of Pt be \(x\). Ethane-1,2-diamine (en) is a neutral ligand. Each chloride ligand contributes: \[ -1 \] Therefore, \[ x+2(-1)=+2 \] \[ x-2=2 \] \[ x=+4 \]

Step 3: Arrange ligand names alphabetically. Ligands present: \[ 2Cl^- \rightarrow dichlorido \] \[ 2(en) \rightarrow bis(ethane\text{-}1,2\text{-}diamine) \] Metal: \[ Platinum(IV) \] Counter ion: \[ Sulfate \] Therefore, the IUPAC name is: \[ \boxed{\text{Dichloridobis(ethane-1,2-diamine)platinum(IV) sulfate}} \]

(ii) Naming of \((NH_4)_2[CoF_4]\)

Step 1: Determine charge on complex ion. Two ammonium ions contribute: \[ 2(+1)=+2 \] Therefore, the complex ion has charge: \[ -2 \]

Step 2: Calculate oxidation state of cobalt. Let oxidation state be \(x\). \[ x+4(-1)=-2 \] \[ x-4=-2 \] \[ x=+2 \]

Step 3: Write the name. Ligand: \[ F^- \rightarrow fluorido \] Four fluorido ligands: \[ tetrafluorido \] Since the complex ion is anionic, cobalt becomes: \[ cobaltate \] Oxidation state: \[ (II) \] Cation: \[ ammonium \] Hence the IUPAC name is: \[ \boxed{\text{Ammonium tetrafluoridocobaltate(II)}} \]