Consider the coordination compound, [Co(NH$$_3$$)$$_6$$]Cl$$_3$$. In the formation of this complex, the species which acts as the Lewis acid is:

We need to identify the Lewis acid in the coordination compound $$[Co(NH_3)_6]Cl_3$$.

Step 1: Understand Lewis acid-base theory.

A Lewis acid is a species that accepts an electron pair. A Lewis base is a species that donates an electron pair.

Step 2: Identify the components of the complex.

In $$[Co(NH_3)_6]Cl_3$$, we have:

- $$Co^{3+}$$ is the central metal ion

- $$NH_3$$ molecules are the ligands (6 of them)

- $$Cl^-$$ ions are the counter ions (3 of them)

Step 3: Determine the Lewis acid.

During complex formation, the central metal ion $$Co^{3+}$$ has empty orbitals that can accept electron pairs. Each $$NH_3$$ molecule has a lone pair on the nitrogen atom, which it donates to the $$Co^{3+}$$ ion.

So $$Co^{3+}$$ acts as the electron pair acceptor (Lewis acid), and $$NH_3$$ acts as the electron pair donor (Lewis base).

Note: $$[Co(NH_3)_6]^{3+}$$ is the complex ion that is formed after the Lewis acid-base interaction. It is the product, not the Lewis acid itself.

The correct answer is Option C: $$Co^{3+}$$.