To determine the correct IUPAC name of the complex `[Cr(H₂O)₅(NCS)][ZnBr₄]`, we will follow these steps:
### Step 1: Identify the oxidation states of the central metal ions.
- **Zinc (Zn)** is in the anionic part of the complex, `[ZnBr₄]`. Each bromine (Br) has a charge of -1, and since there are four bromines, the total charge contributed by bromines is -4. Therefore, to balance this, zinc must be in the +2 oxidation state.
- **Chromium (Cr)** is in the cationic part of the complex, `[Cr(H₂O)₅(NCS)]`. The overall charge of the complex is neutral, and since the zinc complex has a -2 charge, chromium must be in the +3 oxidation state to balance the charge.
### Step 2: Identify the ligands and their names.
- The ligands present in the complex are:
- Five water molecules (H₂O), which are called "aqua" in coordination chemistry. Since there are five, it is named "pentaqua".
- One isothiocyanate ion (NCS), which is named "isothiocyanato".
### Step 3: Assemble the name of the cationic complex.
- The cationic complex is named by listing the ligands in alphabetical order followed by the name of the central metal with its oxidation state in Roman numerals.
- The ligands are "pentaqua" and "isothiocyanato". In alphabetical order, "isothiocyanato" comes before "pentaqua".
- Therefore, the name of the cationic complex is "isothiocyanato pentaquachromium(III)".
### Step 4: Assemble the name of the anionic complex.
- The anionic complex is `[ZnBr₄]`. Since there are four bromine ligands, it is named "tetrabromo".
- The metal zinc is named "zinc", and since it is in the anionic complex, we add "ate" to the name, making it "zincate".
### Step 5: Combine the names of the cationic and anionic complexes.
- The full IUPAC name is constructed by combining the name of the cationic complex followed by the name of the anionic complex.
- Thus, the complete IUPAC name of the complex is "isothiocyanato pentaquachromium(III) tetrabromozincate(II)".
### Final Answer:
The correct IUPAC name of `[Cr(H₂O)₅(NCS)][ZnBr₄]` is **isothiocyanato pentaquachromium(III) tetrabromozincate(II)**.
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