## Computational methods

Both the data sets presented here were constructed using the same methodology summarized here and described in detail in the paper.

### Geometry optimizations

The geometries of the equilibrium structures were optimized at B3LYP-D3/def2-QZVP level using very fine DFT grid and tight convergence thresholds. All the resulting structures had been verified to be true minima by a vibrational analysis. From the equilibrium structures, the dissociation curves were constructed using a protocol described in the paper.

### Benchmark interaction energies

The interaction energies are calculated using a composite CCSD(T)/CBS scheme constructed from a HF energy, MP2 correlation energy extrapolated to the CBS limit, and a ΔCCSD(T) correction. All the calculations employed the counterpoise correction

For the equilibrium geometries and the closest point of the dissociation curves, the scheme employs aug-cc-pV5Z basis for the HF energy, MP2 term is extrapolated from aug-cc-pVQZ and aug-cc-pV5Z basis sets and the ΔCCSD(T) correction in heavy-aug-cc-pVTZ basis. The remaining points of the curve were calculated using smaller basis sets and rescaled to match the high-level benchmark; this procedure had been proven to introduce truly negligible errors.