The complex ion [Cu(H2O6]2+ has an absorption maximum at around 800 nm. When four ammonias replace water,

Question:

The complex ion [Cu(H2O6]2+ has an absorption maxi¬mum at around 800 nm. When four ammonias replace water, [Cu(NH3)4(H2O)2+, the absorption maximum shifts to around 600 nm. What do these results signify in terms of the relative field splittings of NH3 and H2O? Explain.