where the parameters ω and κ were determined according to the linear vibronic coupling model for [Fe(terpy)2] 2+ in Ref. 88. The electronic coupling was calculated according to Equation 4, using the calculated ∆EST and ∆EQT given in Table . A spin-orbit coupling constant of ζ = 47 cm -1 gave a value of about 2.7 ns for the lifetime of [Fe(terpy)2] 2+ , so this was used in all calculations. The approximation method based on Equation 7 is denoted as AM-4.