Your extent needs to be a rectangle so you would need to find out the width and height of your data frame to be able to create an AOI from your point, i.e. if your point is the bottom left corner:
xmapdistance = df.extent.XMax - df.extent.XMin
ymapdistance = df.extent.YMax - df.extent.YMin
extentxmin = 178434
extentxmax = 178434 + xmapdistance
extentymax = 662446
extentymin = 662446 + ymapdistance
df.panToExtent(arcpy.Extent(extentxmin,extentymax,extentxmin,extentymax))