# What is the hybridization of copper in [Cu(NH3)4]^{+2}? [duplicate]

In the valence bond theory section of my textbook, for the $$\ce{[Cu(NH_3)_4]^{2+}}$$ complex it is written:

"... physical measurements have indicated that the complex has square planar geometry. One electron from 3d-subshell shifts to 4p-orbital and hence forming four dsp2 hybrid orbitals."

Further, it is stated that this shouldn't happen, and that Huggin suggested that it be a case of sp2d hybridization.

However, in the CFT section of the same book, the hybridization given is dsp2. Which is correct? And why?