Question

Why is Cu2[Fe(CN)6] chocolate brown, and [Fe(H2O)5NO]2+ the rust brown? Both have the same central metal ion, right?

Answer 1

What is the central metal ion in each?

Answer 2

Fe2+

Answer 3

(don't forget the charge on the [Fe(H2O)5NO] :-) )

Answer 4

So what is different about the two complexes?

Answer 5

I'm signing off, so real quick:
The ligands in each compound are different, which leads to different color changes due to different energy levels in the complex bonds. That's a very, very broad answer, so maybe someone else can fill you in :-) Good luck

Answer 6

Oh yes, I understood. So, you're saying that the CFSE is different for both the complexes and that causes the difference in colour due to excitation of an electron?

Answer 7

:-) yes, more exactly! bye