Advancing the understanding of the HS-ES → LE-ES deactivation mechanisms in low-Z TMC through ultrafast multi-technique probing and theoretical modeling has overhauled their involvement into photoconversion schemes. In particular, square planar Ni(II) complexes have been examined in connection with their applications as potential luminophores (Ogawa2023) or as catalysts in cross-coupling reactions (Ogawa2022). For the majority of these complexes, the GS is planar, while the deactivating MC state is distorted. In a series of tailored complexes, rigidification of the coordination scaffold and steric protection of the Ni(II) center result in a definite deceleration of the CT → MC transition, i.e. a prolongation of the CT lifetime up to ∼ 50 ps. For NiTMP, the GS is ruffled, while the MC state is planar. The initial deformation of the GS geometry controls the amount and the nature of the CT character in the GS → FCS transition (Figure , 1f). Although chemical substitutions tuning the ruffling of NiPs are well established (Schindler2018), a finer control on the LC/CT character of the B and Q bands may prove more challenging. Investigating systematically the impact of steric encumbrance on the characteristics of the CT stage will provide additional insight. The effect of vibrational distributions evidenced in Figure , conformational distributions and possibly ligation of solvent molecules should also be considered. In addition, the present work establishes that the CT → MC in NiP is governed by complex vibronic multi-dimensional dynamics in specific crossing regions of the excited-state energy landscape. Upcoming investigations will focus on elucidating the intricate role of ISC and vibronic coupling in the vicinity of the FC region. Although the lifetimes of the CT manifold in most isolated NiP will remain too short for optimal participation into bimolecular reactions, they are already sufficiently long for them to be considered as partners in short-range CT reactions. For example, COF and MOF materials containing NiP have already demonstrated state-of-the art performances (ref). Based on the CT stage unveiled in this work, extension of their applications to the dynamical management of hot carriers in such structures can be proposed.