Herein, we present a photocatalyst that includes a new peripheral ligand, N,N '-propylene-protected 1H,1'H -2,2'-biimidazole (prbim), to fulfill this. As recently shown, the criterion that renders prbim a spectator ligand is a high-energy lowest unoccupied molecular orbital (LUMO), which is thus not part of the 1 MLCT excitation process and does not contribute to the photophysics of the photocatalyst. Very recently, the effect of such prbim (and related) ligands on the light-harvesting properties and excited state relaxation channels associated with undesirable charge recombination was also investigated computationally for a series of structurally closely related Ru-B-Rh photocatalysts. The photocatalyst prbimRuPt, i.e., [(prbim)2Ru(tpphz)PtI2] 2+ incorporates two prbim ligands as peripheral spectator ligands and therefore conceptually facilitates unidirectional electron transfer from PS to CAT.