Summary of the dynamics observed for 1 and 2 in the transient spectroscopy^a.

	Assignment
1 (Ni II )
0.37 ps	Solvation dynamics
1.1 ps	1NiII* → MC/CT
2.5 ps	MC/CT → MC
14 ps	Spectral narrowing, e.g., vibrational relaxation
81 ps	Combined MC → GS and MC → MC/CT
772 ps	MC/CT → ground state (GS)
2 (Zn II )
2 ps	Solvation dynamics
62 ps	Geometric relaxation
1.1 nsb	SE loss/1ZnII* → 3ZnII
580 ns	Relaxation within 3ZnII manifold
1 μs	Decay of ligand-centered 3ZnII state
5 μs	Ligand dissociation (tentative)
140 μs	Ligand re-association (tentative)

^aFit statistics, selected traces and residuals can be found in the ESI, Fig. S66, S67 and Table S11.

^bTime constant determined from fluorescence decay. The same constant as determined from the fs–ps TA measurements is 770 ps with a large error, since this is close to the full scanning range. For the ns–μs experiment a value of 1.5 ns is obtained, shorter than the 2.7 ns excitation pulse.