Question

Identify the correct IUPAC name of [CoCl$_2$(NO$_2$)(NH$_3$)$_3$]

• A. Triamminedichloridonitrito-N-cobalt(III)
• B. Dichloridotriamminenitrito-O-cobaltat(II)
• C. Dichlorortriamminenitrito-N-cobalt(II)
• D. Triamminedichloronitrito-O-cobalt(III)

Hint:

In naming coordination compounds, remember that the ligands are named before the metal ion, and the oxidation state of the metal is indicated in parentheses.

Answer 1

The Correct Option is A

The compound \([CoCl_2(NO_2)(NH_3)_3]\) is a coordination complex containing cobalt as the central metal ion, chlorine (Cl), nitrite (NO$_2$), and ammonia (NH$_3$) ligands. 1. Cobalt oxidation state: The cobalt ion in this complex is in the +3 oxidation state, as indicated by the ligands attached to it. - The oxidation state of cobalt is determined by the charges of the other ligands. Ammonia (NH$_3$) is neutral, chloride (Cl) is \(-1\), and nitrite (NO$_2$) is also \(-1\). Therefore, cobalt must have a \(+3\) oxidation state to balance the charges of the ligands. 2. Ligand naming: - Ammonia (NH$_3$) is named as "ammine." - Chloride (Cl) is named as "chloro." - Nitrite (NO$_2$) is a bidentate ligand that can bind through either the nitrogen or oxygen atom. In this case, the nitrogen atom of nitrite coordinates with cobalt, so it is named "nitrito-N." 3. IUPAC Naming: The IUPAC name follows the standard order of ligands: - First, we list the ammonia ligands as "triamine" because there are three ammonia molecules. - Next, we list the chloride ligands as "dichloro." - Finally, we list the nitrite ligand as "nitrito-N." - Since the metal ion is in the +3 oxidation state, we indicate it as "cobalt(III)." Thus, the correct IUPAC name of the complex is Triamminedichloridonitrito-N-cobalt(III).