. Author manuscript; available in PMC: 2010 Oct 13.

Published in final edited form as: J Chem Theory Comput. 2009 Oct 13;5(10):2702–2716. doi: 10.1021/ct9002898

Table 1.

Computed Binding Energies (kcal/mol) for the Formation of the Ion-Dipole (ΔE₁) Complex, the Barrier Height Relative to the the IP Complex (ΔE^‡), the Relative Energy between the Reactant and Product Ion–Dipole Complexes (ΔE₂), and the Net Energy of Reaction (ΔE_rxn) between the Product and Reactant States for the S_N2 Reactions (see Scheme 1)

	DFT-VB(2)^a	DFT-VB(3)^a	B3LYP^a	M06-2X^b	CCSD(T)^b	NSBH6^c
			[Cl⁻ + CH₃Cl]
ΔE₁	−7.8	−9.0	−9.5	−11.3	−10.9	−10.5
ΔE^‡	18.3	12.5	8.6	13.2	12.6	13.6
ΔE₂	−7.8	−9.0	−9.5	−11.3	−10.9	−10.5
ΔE_rxn	0.0	0.0	0.0	0.0	0.0	0
			[F⁻ + CH₃Cl]
ΔE₁	−12.3	−15.0	−16.0	−17.1	−16.1	−16.4
ΔE^‡	7.1	2.5	0.3	3.6	2.9	2.9
ΔE₂	−7.4	−8.0	−8.4	−10.0	−9.7	−10.5
ΔE_rxn	−34.3	−34.3	−34.3	−35.8	−32.2	−32.7
			[HO⁻ + CH₃F]
ΔE₁	−11.6	−10.0	−13.7	−14.6	−13.8	−13.7
ΔE^‡	17.9	10.7	6.1	12.3	10.8	11.0
ΔE₂	−6.6	−7.5	−8.1	−9.6	−9.2
ΔE_rxn	−23.3	−23.3	−23.3	−20.7	−19.6	−20.1

The VWN5 functional was used in the B3LYP implementation in GAMESS with the 6-31+G(d) basis set. Values in parentheses are computed using three VB configurations.

Computed using the aug-cc-pVTZ basis set at the QCISD/MG3 geometry.

Ref ⁷⁶.