Theoretical Studies on Relative Stability of Cationic 1,10-Phenanthroline Palladium Complexes Bearing Alkyl Groups by Using Designed Alkane Templates

Density functional theory (DFT) calculations were conducted by using designed alkane templates, 2-methylpentane and 2-methylhexanes, which allowed for effective comparison of relative stabilities of alkylpalladium complexes with various numbers of branches at the α-carbon and the agostic β-carbon. The calculation results suggested that the alkylpalladium complexes bearing a 1,10-phenanthroline ligand are more stabilized when they have more branches at the α-carbon. In addition, the complexes with an agostic β-C(2°)–H or β-C(3°)–H bond generally have Gibbs free energies lower than those with an agostic β-C(1°)–H bond.