The IUPAC name for the complex \(Hg[Co(SCN)_4]\)

Mercury tetrathiocyanatocobaltate (III)

The correct answer is option 1.Mercury tetrathiocyanatocobaltate (III).

The correct IUPAC name for the complex \(Hg[Co(SCN)_4]\) is Mercury tetrathiocyanatocobaltate (III).

Detailed Explanation:

To determine the correct IUPAC name, let's break down the complex \(Hg[Co(SCN)_4]\) step by step.

Identify the Central Metal Atom in the Anionic Complex:

The central metal atom in the complex ion \([Co(SCN)_4]^{2-}\) is cobalt (Co).

The ligands attached to cobalt are thiocyanate ions (SCN^-).

Determine the Oxidation State of Cobalt:

Assume the oxidation state of cobalt in \([Co(SCN)_4]^{2-}\) is \(x\).

Each thiocyanate ligand (SCN^-) has a charge of \(-1\).

The overall charge of the complex ion \([Co(SCN)_4]^{2-}\) is \(-2\).

Therefore, the equation for the oxidation state of cobalt is:

\(x + 4(-1) = -2\)

\(x - 4 = -2\)

\(x = +3\) 

So, the oxidation state of cobalt is +3.

The ligand "\(SCN^-\)" is called thiocyanato in IUPAC nomenclature

Since there are four thiocyanate ligands, it is prefixed as "tetra".

When the complex ion is an anion, the name of the central metal ends in "-ate" and the oxidation state is indicated in Roman numerals.

The anionic complex \([Co(SCN)_4]^{2-}\) is named "tetrathiocyanatocobaltate(III)".

The cation is \(Hg^{2+}\) (mercury).

Therefore, the entire complex is named as "mercury tetrathiocyanatocobaltate (III)".

Summary: The correct IUPAC name for \(Hg[Co(SCN)_4]\) is Mercury tetrathiocyanatocobaltate (III).

So, the correct answer is Option 1.