[xshadow]

Don't understand why in a solution Cu2+ is coloured

I know that colours in transition metal complex are due to electron d-d transition  of metal complex

For example from a t2g  orbital to a eg orbital.
Now Cu²⁺ is a d⁹.

But in an aqeous solution when I say Cu²⁺ I should think at Cu(H2O)_6n

Thanks

[ACETAT]

Cu2+ waterfree is  not coloured,. In binare  compounds black to brown, like CuO, CuS, CuF2, CuSO4 is white. Coloured mostly blue to green are complexes with water, ammonia, etc.

[Orcio_87]

If my memory is correct - that what we see as blue, red or yellow, absorbs opposing light colour (here it will be orange).

Absorbed light will promote one electron from t_2g to e_g orbital.

[xshadow]

Oky!!
I mean water solution....

When I see Cu2+ (aq) can I think at somethung like [Cu(H₂O)₆]²⁺??

Thanks

[Orcio_87]

Yes, but it's geometry is distorted from regular octahedral (two of the Cu-O bonds are longer).