Question

The coordination number of aluminum ion and the number of bridging hydrogen atoms in [Al(BH4)4]⁻ are, respectively,

• A. 8 and 8
• B. 6 and 6
• C. 4 and 6
• D. 8 and 12

Hint:

In coordination compounds, the coordination number refers to the number of bonds between the central metal atom and its ligands.

Answer 1

The Correct Option is A

Step 1: Understanding the structure.
The \([Al(BH_4)_4]^-\) ion consists of an aluminum ion surrounded by four borohydride (\(BH_4\)) groups. Each \(BH_4\) group donates one hydrogen atom to form bridging bonds between the aluminum and the hydrogen atoms from adjacent \(BH_4\) groups.

Step 2: Determining the coordination number.
The aluminum ion is coordinated to 4 \(BH_4\) groups, and each \(BH_4\) group forms one bond with the aluminum. Therefore, the coordination number of the aluminum ion is 6 (4 from \(BH_4\) and 2 from bridging hydrogen atoms).

Step 3: Conclusion.
The coordination number of aluminum is 6 and the number of bridging hydrogen atoms is 6, so the correct answer is (B).