Very unusual.
It is a classical lowpass with a series capacitor at the input that attenuates low frequencies and dc.
You are asking for the center frequency - but how do you define (in this 3rd order case) the center frequency?
Edit: Classical bandpass responses are of 2nd order (or n=4,6...).
In this (unusual) case with n=3, you have two possible choices for defining the center frequency: maximum of transfer function or phase shift of 225 deg (mid between +90 and 360)