Table 1.

Comparison of calculated electronic binding energies, ΔE (kcal/mol),^[a] with experimental gas phase ΔH (kcal/mol) values for Cl^– complexes with simple hydrogen bond donors.

Donor	ΔE (DFT)[b]	ΔE (MP2)[c]	Δ H
pyrrole	–23.09	–22.50	–18.8[3b]
benzene	–8.32	–8.42	–8.6 to –10.5[3b, 10a, 17]
methane	–3.06	–3.36	–3.6[18]

^[a]ΔE = E(complex) – E(chloride) – E(donor). Electronic structure calculations were performed with NWChem.^[19]

^[b]B3LYP/DZVP2

^[c]MP2/aug-cc-pVDZ