We have examined elementary oxidative addition reactions involving the Ir(PH3)2X (X = Cl, H, Li, BH2, NH2, F, Ph) system and small substrates such as dihydrogen (H2), methane (CH4) and fluoromethanes (CH3F, CHF3, CF4), and ethane (C2H6). Electronic structure calculations employed the B3LYP hybrid density functional, an effective core potential on the metal atom, and basis sets of valence double-zeta or better quality. H-H and, in some cases, C-H bond activation occurs with no apparent or only modest activation energy barriers. The cleavage of C-F bonds, in contrast, requires surmounting a sometimes substantial activation energy barrier as does C-C cleavage, even though these addition reactions are also thermodynamically favorable. A substituent effect study shows that π-donation from the ancillary ligand X favors the addition reaction, whereas σ-donation from X is unfavorable.
ASJC Scopus subject areas
- Chemical Engineering(all)