Charge density of 4-methyl-3-[(tetrahydro-2H-pyran-2-yl)oxy]thiazole-2(3H)-thione. A comprehensive multipole refinement, maximum entropy method and density functional theory study

Abstract

The structure of 4-methyl-3-[(tetrahydro-2H-pyran-2-yl)oxy]thiazole-2(3H)thione (MTTOTHP) was investigated using X-ray diffraction and computational chemistry methods for determining properties of the nitrogen-oxygen bond, which is the least stable entity upon photochemical excitation. Experimentally measured structure factors have been used to determine and characterize charge density via the multipole model (MM) and the maximum entropy method (MEM). Theoretical investigation of the electron density and the electronic structure has been performed in the finite basis set density functional theory (DFT) framework. Quantum Theory of Atoms In Molecules (QTAIM), deformation densities and Laplacians maps have been used to compare theoretical and experimental results. MM experimental results and predictions from theory differ with respect to the sign and/or magnitude of the Laplacian at the N-O bond critical point (BCP), depending on the treatment of n values of the MM radial functions. Such Laplacian differences in the N-O bond case are discussed with respect to a lack of flexibility in the MM radial functions also reported by Rykounov et al. [Acta Cryst. (2011), B67, 425-436]. BCP Hessian eigenvalues show qualitatively matching results between MM and DFT. In addition, the theoretical analysis used domain-averaged fermi holes (DAFH), natural bond orbital (NBO) analysis and localized (LOC) orbitals to characterize the N-O bond as a single bond with marginal character. Hirshfeld atom refinement (HAR) has been employed to compare to the MM refinement results and/or neutron dataset C-H bond lengths and to crystal or single molecule geometry optimizations, including considerations of anisotropy of H atoms. Our findings help to understand properties of molecules like MTTOTHP as progenitors of free oxygen radicals.

Bonding features in Appel's salt from the orbital-free quantum crystallographic perspective

“…The electron density point of view on halogen bonds has been thoroughly presented in the recent works dealing with the NÁ Á ÁI bond (Wang et al, 2018), interactions in tetrafluorodiiodobenzene (Wang et al, 2019) and short ClÁ Á ÁCl bonding (Wang et al, 2012(Wang et al, , 2017. The bonding in 3-alkoxy-4-methylthiazole-2(3H)-thione (Vé nosová et al, 2020), which is one of the most frequently used progenitors of oxygen radicals, is discussed with the main focus on the features of the N-O bond involved in radical generation.…”

Evaluation of inhibitive corrosion potential of symmetrical hydrazine derivatives containing nitrophenyl moiety in 1M HCl for C38 steel: experimental and theoretical studies

“…To investigate non-covalent interactions (NCI) which can characterize inhibitor structure, an empirical dispersion GD3 scheme by Grimme was added to the B3LYP functional at DFT theory [23] , [24] . Unlike B3LYP, the corrected functional B3LYP-GD3 appears to be reliable for investigating non-covalent interactions [23] , [24] . The NCI calculations were performed using Multiwfn and VMD software [25] .…”

Noncovalent Bonds through Sigma and Pi-Hole Located on the Same Molecule. Guiding Principles and Comparisons

“…Quite the opposite from representing exotic or unusual contacts, these bonds make important contributions to numerous fields of chemistry and biology. As examples, understanding the forces behind crystal engineering and supramolecular chemistry benefits from a knowledge of σ-hole interactions due to their directionality, strength, and self-organization properties which promote formation of adducts in the solid state [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. The importance of σ-hole bonding has also been verified in the context of anion recognition processes [ 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ], materials chemistry [ 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ], or biochemistry [ 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ].…”