Calculated free energy barriers for inner and outer sphere C–CO2 bond formation with different pincer-supported palladium and nickel complexes (kcal mol−1, B3LYP-D3/def2-TZVPPD[CPCM]//B3LYP-D3/def2-SVP[CPCM], 298 K)a.
| Complex | TS1_Out (kcal mol−1) | TS1_Inn (kcal mol−1) |
|---|---|---|
| (tBuPBP)Pd(CH3) | 19.0 (23.9) | 25.1 (30.6) |
| (MePBP)Pd(CH3) | 22.5 (23.4) | 19.4 (21.0) |
| (tBuPBP)Ni(CH3) | 24.5 (27.8) | 31.9 (33.7) |
| (tBuPCP)Pd(CH3) | 24.2 (29.2) | 36.7 (41.1) |
| (MePCP)Pd(CH3) | 26.8 (30.0) | 25.0 (27.8) |
a
For comparison, results for the ωB97XD functional are given in parenthesis, showing the same mechanistic trends.