Table 3.

Imaginary frequencies (i), distances of the carbon atom of the methine group in o-QMR[4]A from the nucleophilic atom in TS and also the activation energies of the reaction of o-QMR[4]A with nucleophiles ($\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{F}}$) and the activation energies of the backward reaction ($\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{B}}$). (Calculations were performed on GFN2-xTB geometries.)

HNu	imaginary mode (i)	distance H2C..Nu	GFN2-xTB (kcal mol−1)		B97-3c (kcal mol−1)		wB97XD (kcal mol−1)
	(cm−1)	(A)	$\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{F}}$	$\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{B}}$	$\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{F}}$	$\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{B}}$	$\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{F}}$	$\mathrm{\Delta }{\mathrm{E}}_{\mathrm{a}}^{\mathrm{B}}$
EtOH	i232.65	2.043	3.70	40.70	6.16	20.53	10.22	30.14
MeSH	i207.64	3.826	3.23	37.98	2,58	28,23	2.53	32.11
morpholine	i25.63	2.827	1.70	45.39	1.75	25.13	3.33	31.58
CH3COOH	i217.45	2.416	10.00	36,90	15.10	22,38	19.30	31.35
2-naphthol	i170.33	2.346	1.97	39.52	3,30	23,48	9.11	34.74