Similar to the case of NH-cooperative Mn(I) catalyst Mn-5 our results reveal the high extent of tridentate ligand dynamics throughout the catalyst activation. The suggested involvement of the N-donor dissociation in the catalytic cycle would rationalize the selectivity flip toward C=C for Mn complexes obtained by blocking the N-H functionality (Table , Figure ). Analysing the crystal structures (Figure and Table ) of methylated Mn-6 and 7 we find that the Mn-N bonds lengths are significantly longer in these complexes compared to their NH counterparts Mn-4, 5. This trend further suggests that conventional pincer and tridentate ligands in Mn(I) complexes might exhibit dynamics and donor ligand lability that is not characteristic for their noble metal-based counterparts. While the catalytic functionality of this behaviour is open to debate, it clearly invites further research into ligand dissociation dynamics of catalytically relevant Mn(I) complexes.