Orbital interaction energies (in kcal mol−1), orbital overlap, energy gap (Δε, in eV), and orbital stabilization for the metal–metal and ligand–ligand donor–acceptor interactions in the [M(CO)2X2]2 dimers (M = Ni, Pd, Pt; X = Cl, Br, I) at a consistent M⋯M bond distance (rM⋯M = 3.5 Å). Computed at ZORA-BLYP-D3(BJ)/TZ2P.
| M | X | ΔEoi | Metal–metal | Ligand–ligand | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| S | Δεa | 103×S2/Δε | %b | S | Δεa | 103×S2/Δε | %b | |||
| Ni | Cl | −3.8 | 0.11 | 8.2 | 1.5 | 53 | 0.07 | 3.8 | 1.3 | 47 |
| Br | −4.9 | 0.09 | 7.8 | 1.0 | 36 | 0.08 | 3.5 | 1.8 | 64 | |
| I | −5.8 | 0.08 | 7.3 | 0.9 | 25 | 0.09 | 3.1 | 2.6 | 75 | |
| Pd | Cl | −4.7 | 0.18 | 8.4 | 3.9 | 67 | 0.08 | 3.4 | 1.9 | 33 |
| Br | −5.6 | 0.17 | 8.1 | 3.6 | 58 | 0.09 | 3.1 | 2.6 | 42 | |
| I | −6.5 | 0.16 | 7.7 | 3.3 | 47 | 0.10 | 2.7 | 3.7 | 53 | |
| Pt | Cl | −5.8 | 0.20 | 8.2 | 4.9 | 67 | 0.09 | 3.3 | 2.5 | 33 |
| Br | −6.8 | 0.18 | 8.1 | 4.0 | 55 | 0.10 | 3.0 | 3.3 | 45 | |
| I | −8.0 | 0.17 | 7.8 | 3.7 | 44 | 0.11 | 2.6 | 4.7 | 56 | |
a
See HOMO and LUMO energies in Tables S1 and S2 (ESI).
b
Contribution of the associated orbital stabilization to the total metal–metal + ligand–ligand orbital stabilization.