Computational Study on the Relative Reactivities of Cobalt and Nickel Amidinates via β-H Migration

Density functional theory calculations were performed to examine the relative stabilities of several Co- and Ni-based amidinates for atomic layer deposition to β-H or β-CH3 migration from the chelating ligand to the metal center atom. The calculated precursor structures are in excellent agreement with the available XRD data. The minimum energy path of the migration process was identified. Our results indicate that the migration process is thermochemically endothermic; however, for Ni( i Pr-MeAMD)2 the reaction is close to thermoneutral. The relatively moderate activation barrier allows β-H migration for Ni( i Pr-MeAMD)2 to occur, leading to instability at the ALD process temperature. Replacing the H atoms with methyl groups can greatly stabilize the precursors to the β-H migration. The results are consistent with the experimental observations.