Question

What are the respective central-metal oxidation state, coordination number, and overall charge for the complex [Co(NH3)5Cl](NO3)2

SHOW WORK

Answer 1

Calculating the oxidation no. of Co :-

• Nitrate ions always have -1 charge, therefore the counter ions (NO₃^​​)₂ give a net charge of -2.
• Therefore, we know [Co(NH_{​​​​​3})₅Cl] must have a +2 charge.
• All NH_{​​​​​3} ligands are neutral and the remaining Cl is -1.

So,

• 5 x NH_{​​​​​3} → 0
• 1 x Cl → -1

Lets take the oxidation state for Co be x.

so, x + (5x0) + (1x-1) = +2

Thus, x = +3

Therefore, the oxidation state of Co in [Co(NH_{​​​​​3}​​​​)₅Cl](NO_{​​​​3})₂ is +3.

Coordination number of Co is 6 since, the number of bonds formed between the metal ion,Co and the ligands (five NH₃ and one Cl) in the complex ion [Co(NH_{​​​​​3})₅Cl]²⁺ gives the coordination number.

The overall charge for the complex [Co(NH_{​​​​​3})₅Cl](NO_{​​​​​3})₂ is zero, i.e, it is neutral.