Table 3. Experimental Values, AIBLHiCoS Predictions, and AE for Implementation of the MLR Equation of T3 Bond Lengths a, b, and d (pK_a = 92.511 × r(a) + 105.33 × r(b) + 33.596 × r(d) – 311.79) for Substituted 2-(Phenylimino)imidazolidines (ph1–Ph15) and 2-(Pyridylimino)imidazolidines (py1–Py3), Where Experimental Values are Taken from One Source^25a.

^aPredictions and errors are also shown for further five literature compounds: tizanidine (Tiz),⁴⁰ apraclonidine (Apra),⁴¹ and AG3–AG5.⁴² Predictions for compounds py4–py7 were made by implementation of the a model, that is, pK_a = 272.76 × r(a) – 368.08, and are denoted by (a). Predictions and AE obtained using ChemAxon using both T1 and T3 as input structures are also shown for comparison, where asterisks denote predictions where the Marvin program recognized the T3 form as the dominant tautomer.