Explain `[Co(NH_3)_6]^(3+)` is an inner orbital complex whereas `[Ni(NH_3)_6]^(2+)` is an outer orbital complex.

Explanation

To explain why `[Co(NH_3)_6]^{3+}` is an inner orbital complex while `[Ni(NH_3)_6]^{2+}` is an outer orbital complex, we can break down the explanation into several steps:

### Step 1: Determine the oxidation states and electron configurations of the metals
- For `[Co(NH_3)_6]^{3+}`:
- Cobalt (Co) in this complex has an oxidation state of +3.
- The electron configuration of cobalt in its elemental form is `[Ar] 3d^7 4s^2`.
- Upon losing 3 electrons (to achieve +3 oxidation state), the configuration becomes `[Ar] 3d^6` (since the 4s electrons are lost first).

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