Question

The metal borides that contain isolated boron atoms are:

• A. Tc\(_7\)B\(_3\) and Re\(_7\)B\(_3\)
• B. Cr\(_5\)B\(_3\) and V\(_3\)B\(_2\)
• C. Ti\(_4\)B\(_4\) and V\(_3\)B\(_4\)
• D. TiB and HfB

Hint:

When identifying borides with isolated boron atoms, look for structures where boron is not part of a cluster or network but exists independently.

Answer 1

The Correct Option is A

Boron atoms in metal borides can exist in different structural environments. Isolated boron atoms are those that are not part of a cluster of boron atoms in the structure. In the case of Tc\(_7\)B\(_3\) and Re\(_7\)B\(_3\), boron atoms are isolated within the structure, making them the correct answer.

Step 1: Review the options.
- (A) Tc\(_7\)B\(_3\) and Re\(_7\)B\(_3\) both contain isolated boron atoms.
- (B) Cr\(_5\)B\(_3\) and V\(_3\)B\(_2\) involve clusters of boron atoms, so they do not contain isolated boron atoms.
- (C) Ti\(_4\)B\(_4\) and V\(_3\)B\(_4\) also contain boron clusters.
- (D) TiB and HfB are typical binary borides, but they do not contain isolated boron atoms.

Final Answer: (A) Tc\(_7\)B\(_3\) and Re\(_7\)B\(_3\)