[Co(NH3)6]3+ and [CoF6]3− are respectively known as:

The complex [Co(NH3)6]3+ is known as Hexaamminecobalt(III) ion and the complex [CoF6]3− is known as Hexafluorocobaltate(III) ion.

Here's the step by step explanation:

1. The name of a complex ion starts with the names of the ligands. In [Co(NH3)6]3+, the ligand is NH3 which is called ammine (not to be confused with amine). In [CoF6]3−, the ligand is F which is called fluoride.

2. The number of ligands is indicated by a prefix. Here, there are six ligands in both complexes, so the prefix is 'hexa'.

3. The metal atom is then named, in this case 'cobalt'.

4. The oxidation state of the metal atom is given in Roman numerals in parentheses. Here, the oxidation state of cobalt is +3 in both complexes.

5. If the complex ion is a cation, the name of the metal is followed by the word 'ion'. If the complex ion is an anion, the name of the metal ends in 'ate' and is followed by the word 'ion'.

So, [Co(NH3)6]3+ is Hexaamminecobalt(III) ion and [CoF6]3− is Hexafluorocobaltate(III) ion.