Abstract
Density functional theory (DFT) was used to elucidate the mechanism of n-butane hydrogenolysis (into propane, ethane, and methane) on well-defined zirconium hydrides supported on SBA15 coordinated to the surface via N-donor surface pincer ligands: [( SiNH-)( SiO=)ZrH2] (A), [( SiNH-)(2)ZrH2] (B), [( SiNH-)( SiO)(2)ZrH] (C), [( SiNH-)(2)( SiO-)(2)ZrH] (D), [( SiN-)( SiO-)ZrH] (E), and [( SiN=)( SiNH-)ZrH] (F). The roles of these hydrides have been investigated in C H/C C bond activation and cleavage. The dihydride A linked via a chelating [N,0] surface ligand was found to be more active than B, linked to the chelating [N,N] surface ligand. Moreover, the dihydride zirconium complexes are also more active than their corresponding monohydrides C F. The C C cleavage step occurs preferentially via beta-alkyl transfer, which is the rate-limiting step in the alkane hydrogenolysis. The energetics of the comparative pathways over the potential energy surface diagram (PES) reveals the hydrogenolysis of n-butane into propane and ethane.