Steps in naming:

To name the complex [Co(H₂O)₄(NH₃)₂]Cl₃ using IUPAC nomenclature, we follow specific rules for coordination compounds.

Step 1: Identify the Central Metal Ion

The central metal ion is Cobalt (Co).

Step 2: Determine the Oxidation State of the Metal

Let the oxidation state of Co be $x$. The ligands are neutral (H₂O and NH₃), and there are three Cl^- ions outside the coordination sphere. The overall charge is zero:

$x+0+0+3\times (-1)=0$

$x-3=0$

$x=+3$

So, the oxidation state is +3, indicated as cobalt(III).

Step 3: List the Ligands in Alphabetical Order

Ligands present: H₂O (named as "aqua") and NH₃ (named as "ammine").

Alphabetical order: "ammine" comes before "aqua" (since 'a' comes before 'q').

Prefixes: diammine (for 2 NH₃) and tetraaqua (for 4 H₂O).

Step 4: Write the Name

Order: ligands in alphabetical order + metal name (with oxidation state) + outer ion.

So, it is: Diamminetetraaquacobalt(III) chloride.

Why Other Options Are Incorrect?

• "Tetraaquadiaminecobalt (III) chloride": Ligands not in alphabetical order ("aqua" should not come before "ammine").
• "Tetraaquadiamminecobalt (III) chloride": Same error, incorrect order.
• "Diaminetetraaquacoblat (III) chloride": Misspelling ("diamine" instead of "diammine", "coblat" instead of "cobalt").

Related Topics and Formulae

IUPAC Naming Rules for Coordination Compounds:

1. Ligands are named first in alphabetical order (ignoring prefixes like di, tri).
2. Neutral ligands have specific names (e.g., H₂O is "aqua", NH₃ is "ammine").
3. Prefixes indicate the number of ligands (di, tri, tetra, etc.).
4. The central metal is named next, with its oxidation state in Roman numerals in parentheses.
5. If the complex is a cation, the metal name is used as is; if anion, it ends with "-ate".
6. Outer ions are named last.

Example Formula: For a general complex [M(L)_a(L')_b]X_c, name is: [alphabetical ligands]metal(oxidation state) [outer ion].