Noteworthy, this ILCT is accelerated compared to the structurally related photocatalyst tbbpyRuPt (0.3 ps -1 ). This can be rationalized by the contribution of the peripheral ligands in the photoinduced dynamics: The energy difference between the tpphz-and prbim-centered MLCT states in prbimRuPt is so large (DFT: ∆E = 1.04 eV, see Figure ) that the prbim states are thermally inaccessible to the initially occupied tpphz-localized states. In contrast, such an interaction between MLCT tpphz and MLCT tbbpy states has been observed for the tbbpyRuPt complex, which can be explained by the lower energy between these states, which is 0.43 eV according to computational results. This additional relaxation pathway in tbbpyRuPt (e.g., interligand hopping) competes effectively with the phen-to-phz ILCT, resulting in an overall longer process. The process characterized by k2 (see grey, dashed line in Figure ) describes the subset of 3 MLCT phen states with excess electron density in proximity to the Pt ion converting into MLCT phz states via ILCT. This is manifested in the decay of features that are centered at around 450 nm and between 620 and 750 nm, which are attributed to LMCT absorption of 3 MLCT phen states. Specifically, TD-DFT supports that the positive features at around 450 nm can be assigned to ESA resulting from phen-to-Pt LMCT absorption (see S17 and T52 in Table and). Such a phen-to-phz ILCT is not observed for tbbpyRuPt, where instead a longlived (>2 ns) MLCT phen(Pt) state is formed. Thus the process associated with k2 can be considered as a factor contributing to the negligible catalytic activity of prbimRuPt compared to, e.g., tbbpyRuPt. Upon both ILCT processes, associated with k1 and k2, a 3 MLCT phz state is formed, which in turn decays with k3. Thus, in direct comparison to tbbpyRuPt, no long-lived excited state (lifetime beyond 2 ns) is populated proceeding from the MLCT phz , but this state directly decays back to the ground state (see Figure ). Such a comparably short lifetime of bridge centered MLCT states, was previously also observed for terpyridine-type bridges. Possible pathways for a vectorial Ru-to-Pt electron transfer across the tpphz bridge, which is desired for proton reduction, may involve a non-radiative transfer from an MLCT phz state either directly or mediated via the peripheral ligands (MLCTL, with L = prbim, tbbpy, fbpy) to a 3 MCPt state. To simulate these two scenarios, we obtained the respective DFT energy gaps from the energies of the 3 MLCT phz , 3 MLCTL, and 3 MCPt states within the optimized geometry of the 3 MCPt state of prbimRuPt as well as of the reference compounds tbbpyRuPt and fbpyRuPt for comparability. For prbimRuPt, (TD-)DFT suggests an energy gap of 0.78 eV for a direct phz-to-Pt electron transfer, i.e., energy difference between the minimum 3 MLCT phz and 3 MCPt states. In comparison, this gap is 0.49 and 0.19 eV for the reference complexes tbbpyRuPt and fbpyRuPt, respectively (see Figure ). On the other hand, the respective 3 MCPt and 3 MLCTL states of tbbpyRuPt and fbpyRuPt are energetically degenerated. In prbimRuPt however, these states are separated by 0.37 eV. Thus, the increased stability of the 3 MLCT phz state in prbimRuPt, granted by the electron rich prbim ligands, may result in an insurmountable activation energy for subsequent electron transfer steps towards the Pt center (see Figure ).