Question

The IUPAC name of the complex \( [\text{Cr(NH}_3)_3(\text{H}_2\text{O})_3]\text{Cl}_3 \) is:

• A. \({triaquatriamminechromium(III) chloride} \)
• B. \({triammnetriaquachromium(III) chloride} \)
• C. \({triaquatriamminechromium(II) chloride} \)
• D. \({triammnetriaquachromium(II) chloride} \)
• E. \({triaquatriamminechromium(III) trichloride} \)

Hint:

For naming coordination complexes, list ligands alphabetically, use appropriate prefixes (di-, tri-, etc.), and state the oxidation state of the metal in Roman numerals.

Answer 1

The Correct Option is B

Step 1: Identify the ligands and their order The given complex is \([{Cr(NH}_3)_3({H}_2{O})_3]{Cl}_3\). Ligands present: \({NH}_3\) (ammine) and \({H}_2{O}\) (aqua). The ligands are named in alphabetical order: \({ammine}\) before \({aqua}\).
Step 2: Determine oxidation state of chromium Let the oxidation state of chromium be \( x \). Each \({NH}_3\) and \({H}_2{O}\) ligand is neutral. The three \({Cl}^-\) ions contribute a total charge of \(-3\). The overall charge on the complex is neutral: \[ x + 0 + 0 - 3 = 0 \] Solving for \( x \): \[ x = +3 \] Chromium is in the \( +3 \) oxidation state.
Step 3: Name the complex The ligands are named alphabetically: "triammine" (three \({NH}_3\)) and "triaqua" (three \({H}_2{O}\)). The metal name "chromium" follows with its oxidation state in Roman numerals \((III)\). The anion \({Cl}_3\) is named as "chloride."
Step 4: Verify the correct name The correct name of the complex is \({triammnetriaquachromium(III) chloride}\). This matches option (B).