There are few common heavy metal/complex anion complexes. That said, Pearson states in his early HSAB publications that transition metal ions of high oxidation state are harder than those of low oxidation state.
Thus, we would only expect transition ionic metal/complex anion complexes to form with the harder higher oxidation state transition metal ions.
This is what is found: the hard/hard copper(II) tetrafluoroborate complex, Cu[II] (BF4)2, is known, but the mixed soft/hard copper(I) tetrafluoroborate, Cu[I] BF4, is not.
However, mixed soft/hard complex silver tetrafluoroborate, AgBF4, is known and is a useful chemical reagent.