Structural manifestations of proton transfer in complexes of 2,6-dichlorophenols with pyridines

Abstract

DFT B3LYP/6-31G(d,p) calculations were performed to describe the proton transfer reaction pathway in the 2,6-dichlorophenolate of pyridine. The aim of these calculations was to establish the character of the dependence of the structure parameters on the proton transfer and comparing the results with known structures, e.g. the 2,6-dichloro-4-nitro- and pentachlorophenolates of pyridines. To make this comparison more reliable, the calculations were repeated with the use of a reaction-field correction with the Onsager radius and electric permittivity taken from the solid-state measurements. The calculations show that the second approach gives a better description of the structural modifications during the proton transfer.

Luminescent and Electronic Properties of Stilbenoid NCN‐Pincer PtII Compounds

“…The ρ (Onsager cavity radius) of the molecule can be estimated by numerous methods, [75,76] and in this study the radii of molecules 6 and 7 were estimated from their solid-state structures (estimated to be 4.36 and 4.39 Å, respectively). [77,78] From the slopes derived from the Lippert plot of 6 and 7 (the values in dichloromethane were excluded from the trend line, Figure 12), ∆µ was estimated to be 11 and 13 D, respectively. This implies that in these systems, excited state charge separation is present but to a lesser extent than that found for related 4,4Ј-substituted stilbenes.…”

Structural modifications resulting from proton transfer in complexes of phenols with pyridine

“…It was shown previously that the structure parameters give more linear correlations with d(CO) than with d(OH). 15,16 The formal degree of the proton transfer (X PT ) was estimated on the basis of the dependence of the calculated dipole moment on d(OH). This dependence was of sigmoid shape, which allows the limiting values of the dipole moments for pure molecular ( HB ) and pure proton transfer complexes ( PT ) to be established.…”

“…Such an approach was first used by us in previous work. 15 In this analysis of the structural consequences of proton transfer, we applied the results of calculations, not experimental structures. According to Kovacs et al,4 with such an approach one avoids some random errors resulting from crystal packing forces.…”

“…The potentials for 2 are according to Ref. 15. The numbers in parentheses are the O Á Á ÁH distance fixed in the procedure of energy minimization in calculations described in constructing the potentials in Fig.…”

“…In previous work, 14 such studies were undertaken in our laboratory, based on experimental results. Density functional theory (DFT) B3LYP/6-31G(d,p) calculations were performed 15 on the structure of the complex of 2,6dichlorophenol with pyridine as a function of the degree of proton transfer modulated by increasing the OÁ Á ÁH distances within the range found in the experiment. The purpose of that study was to give a theoretical description of the observed tendencies in 15 crystal structures of 2,6dichlorophenols and various pyridine derivatives, 14 partly because of the wide spread of experimental points, resulting mainly from differences in the crystal packing forces.…”