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DFT study of the ring opening polymerization of ε-caprolactone by grafted lanthanide complexes: 1--Effect of the grafting mode on the reactivity of borohydride complexes.

The influence of the grafting mode of a borohydride lanthanum complex on a silica surface on the energetic (kinetic and thermodynamic parameters) of the Ring Opening Polymerization (ROP) reaction of ε-caprolactone has been studied in the framework of density functional theory (DFT). For all considered grafted catalysts (monografted, bigrafted, or bigrafted after breaking of a Si-O-Si bridge), it is shown that lanthanum borohydride grafted complexes are efficient in lactone polymerization. Moreover, the reaction pathways (leading to a -CH(2) OBH(2) chain end) are predicted to be energetically similar for the three grafting modes, indicating that all grafted modes can account for the activity for silica treated at 700 °C. The catalytic activity of the grafted complexes is also very similar to that of the homogeneous complexes.