# Are there any geometric isomers of the stable octahedral complex #[Co(NH_3)_3(NO_2)_3]#? If there are, how many?

##### 2 Answers

Facial and meridional isomers are possible with respect to the octahedral complex.

#### Explanation:

The

You *could* use the **Bailar method**, gone through in detail here, to determine how many isomers there are, as it is more generalized for all octahedral complexes.

*However*, since we have a **two** possible isomers: *fac* and *mer*.

**THE FAC ISOMER**

The ** fac (facial) isomer** has the three identical ligands aligned such that there is a

**it can be drawn in a Newman projection with a front-rear bond length of**#\mathbf(0)# .

What I had just said can be drawn as follows:

So you can see that if you rotate the molecule about that **you get the same molecule back**.

Furthermore, you can find a **mirror plane** that coincides with an *trans* to each other, and bisects two *cis* **not chiral**.

Therefore, the *fac* isomer is NOT an enantiomeric isomer and is the **only** *fac* isomer there is.

**THE MER ISOMER**

The ** mer (meridian) isomer** has three

In essence, I switched the top-axial

So you can see that if you rotate the molecule about that

Furthermore, you can find a **mirror plane** that is coplanar with the **not chiral**.

Therefore, the *mer* isomer is NOT an enantiomeric isomer and is the **only** *mer* isomer there is.

**CHECKING THE RESULT**

In fact, if you look at the following table, the **two** stereoisomers, neither of which are enantiomers.

Since a **geometric isomer** has the *same* connectivity but *different* spatial orientations, these stereoisomers, which agree with that definition, are also geometric isomers!

**Thus, we have all geometric isomers identified.**