. Author manuscript; available in PMC: 2011 Jan 14.

Published in final edited form as: J Phys Chem B. 2010 Jan 14;114(1):349–360. doi: 10.1021/jp9082085

Table 1.

IEF-PCM calculated (B-BH⁺) energy and free energy differences in the aqueous solution^a

	ΔE^s_int	ΔG(T)_th	ΔE_elst	ΔG_drc	ΔG_sol	ΔG_tot
B3LYP/6-31G*
Piperidine	238.4	−9.7	54.1	−0.3	53.9	282.6
N-Me piperidine	241.6	−9.7	49.7	−0.3	49.4	281.3
Piperazine^b	237.2	−9.1	53.7	−0.3	53.5	281.6
B3LYP/6-311++G**
Piperidine	235.4	−9.7	53.7	−0.2	53.5	279.2
N-Me piperidine	239.5	−9.8	49.3	−0.3	49.0	278.8
Piperazine^b	233.7	−9.0	53.5	−0.2	53.3	278.0
B3P86/6-311++G**
Piperidine	236.3	−9.8	53.6	−0.2	53.4	279.9
N-Me piperidine	240.2	−9.8	49.2	−0.3	48.9	279.3
Piperazine^b	234.6	−9.1	53.4	−0.2	53.2	278.7
	ΔE^s_int					ΔG_sol
	MP2 aug-cc-pvdz	MP2 aug-cc-pvtz/SP	MP2_CBS	QCISD(T) aug-cc-pvdz/SP	QCISD(T)^c CBS
Piperidine	233.2	233.7	233.9	234.8	235.4	53.6
N-Me piperidine	237.6	237.9	238.1	239.4	239.8	49.2
Piperazine	231.3	231.8	232.0	232.9	233.5	53.7

Energy terms in kcal/mol. By approximating ΔG^o_tot as ΔG_tot, ΔG_tot was calculated according to eq. 3.

Entropy decreased by 0.41 kcal/mol for the neutral piperazine due to a rotational symmetry number of 2 for a species with C_2h symmetry.

The ΔE values were calculated as ΔE (QCISD(T)/CBS) = ΔE(MP2_CBS)+(ΔE(QCISDT(aug-cc-pvdz))-ΔE(MP2(aug-cc-pvdz))).The ΔE(MP2_CBS) values were estimated on the basis of aug-cc-pvdz optimization and aug-cc-pvtz single-point calculations. MP2 thermal corrections deviate from the B3LYP/6-311++G** values by up to −0.1 kcal/mol.