The shape of Copper Tetraamine Complex

[Harmony]

Why is Copper Tetraamine Complex a square plane? Shouldn't it be tetrahedral since there is only four bond pairs?

[GCT]

It has to do with several factors related to the atom itself and the energy parameters associated with the molecular energy levels. I don't have my inorganic text at the moment, are you trying to apply VSEPR?

[Harmony]

Yes. I tried to apply the VSEPR Theory, but it seems that the theory is not sufficient to explain the shape of the complex. Does this have anything to do with the size of the ligand?