Question

Although we are accustomed to thinking of transition metal complexes as brightly coloured, there are several that are not. For each of the following, present a reason for the described observation(s): [ related to: △l = +/-1 Rule；Spin Selection Rule；Laporte Selection Rule ]

d) [Au(CN) 4]- and [Co(CN)6]3- complexes form white crystals when combined with colourless cations.

c) [Co(H2O)6] 2+ is pale pink, although [CoCl4] 2- is deep blue.

Answer 1