BCN-C10 was selected as the dienophile for kinetics analysis. It is a crystalline compound and has long storage lifetime compared to liquid or amorphous BCN derivatives. The second order rate constants for the ligand 7 and the complex 3 in reaction with BCN-C10 were determined as 0.0025 and 0.0081 M -1 s -1 respectively, demonstrating that coordination to Ir(III) metal ion facilitates the IEDDA reaction. However, the magnitude of metal coordination effect in 7/3 pair is much less profound than in 6/2 analogues. (Figure ). The rationale underpinning these observations is discussed in below, with reference to computational analysis. The relatively low reaction rate of 3 limits biorthogonal applications of these complexes in vivo unless either reagent is present in a large excess.