Structure of Carborane, CB8H14, based on Wade's rules of electron counting

Wade's rules of electron counting are used to predict the structure of cluster compounds such as carboranes. Carboranes are a class of compounds that consist of carbon, boron, and hydrogen atoms. The structure of carborane, CB8H14, can be predicted using Wade's rules of electron counting.

Wade's Rules of Electron Counting

- Rule 1: Count the total number of valence electrons contributed by each atom in the cluster.
- Rule 2: Assume that all atoms in the cluster are bonded to each other by two-electron, covalent bonds.
- Rule 3: Start with the minimum number of skeletal electrons required to connect all of the atoms in the cluster with two-electron bonds.
- Rule 4: Add additional pairs of electrons to the skeleton until all valence electrons have been used.
- Rule 5: The structure with the lowest number of skeletal atoms is the most stable.

Prediction of the Structure of Carborane, CB8H14

- Rule 1: Carbon has 4 valence electrons, boron has 3 valence electrons, and hydrogen has 1 valence electron. Therefore, the total number of valence electrons in carborane is:

4(C) + 3(B) + 14(H) = 32

- Rule 2: Assume that all atoms in the cluster are bonded to each other by two-electron, covalent bonds.

- Rule 3: Start with the minimum number of skeletal electrons required to connect all of the atoms in the cluster with two-electron bonds.

There are two possible skeletal structures for carborane, as shown below:

- Rule 4: Add additional pairs of electrons to the skeleton until all valence electrons have been used.

There are two possible structures that can be obtained by adding additional pairs of electrons to each skeletal structure:

- Rule 5: The structure with the lowest number of skeletal atoms is the most stable.

The second structure has a lower number of skeletal atoms and is therefore the most stable. This structure is known as the arachno-structure and is shown below:

Therefore, based on Wade's rules of electron counting, the structure of carborane, CB8H14, is expected to be arachno.