The nature of E⋯E′ in 1-RE–8-R′E′C10H6 (E/E′ = O, S, Se and Te) is clarified with the QTAIM approach and NBO analysis, after structural determinations.
The dynamic and static nature of various neutral hydrogen bonds (nHBs) is elucidated with quantum theory of atoms‐in‐molecules dual functional analysis (QTAIM‐DFA). The perturbed structures generated by using the coordinates derived from the compliance force constants (Cij) of internal vibrations are employed for QTAIM‐DFA. The method is called CIV. The dynamic nature of CIV is described as the “intrinsic dynamic nature”, as the coordinates are invariant to the choice of the coordinate system. nHBs are, for example, predicted to be van der Waals (H2Se−✶−HSeH; ✶=bond critical point), t‐HBnc (typical‐HBs with no covalency: HI−✶−HI), t‐HBwc (t‐HBs with covalency: H2C=O−✶−HI), CT‐MC [molecular complex formation through charge transfer (CT): H2C=O−✶−HF], and CT‐TBP (trigonal bipyramidal adduct formation through CT: H3N−✶−HI) in nature. The results with CIV were the same as those with POM in the calculation errors, for which the perturbed structures were generated by partial optimization, and the interaction distances in question were fixed suitably in POM. The highly excellent applicability of CIV for QTAIM‐DFA was demonstrated for the various nHBs, as well as for the standard interactions previously reported. The stability of the HBs, evaluated by ΔE, is well correlated with Cij (ΔE×Cij=constant value of −165.64), and the QTAIM parameters, although a few deviations were detected.
Investigations concerning the nature of interactions must be considered an issue of primary importance in the chemical sciences. The dynamic and static natures of interactions were recently proposed based on the quantum theory of atoms in molecules dual functional analysis (QTAIM‐DFA). The nature of interactions is widely investigated under various conditions, which often results in the predictions of (very) different natures. The predicted nature should be well correlated to the observed parameters, especially for experimental scientists. The effects from the basis sets and levels of calculations on the predicted parameters are carefully examined, exemplified by the interaction distances in question, the QTAIM functions for the interactions, and the QTAIM‐DFA parameters. The effects are discussed for the total (basis set + level) terms and each term. The mechanisms of the total terms are also clarified for the QTAIM‐DFA parameters. The results provide a good guideline for discussion of the nature of interactions based on the calculated parameters under various calculation conditions. The results help to establish a reliable method to elucidate the nature of interactions, such as QTAIM‐DFA.
The dynamic and static nature of each hydrogen bond (HB) in acetic acid dimer (1), acetamide dimer (2a), thio- and seleno-derivatives of 2a (2b and 2c, respectively), and acetic acid–acetamide mixed dimer (3) was elucidated with QTAIM dual functional analysis (QTAIM-DFA). Such multi-HBs will form in 1–3, in close proximity in space, and interact mutually and strongly with each other. Perturbed structures generated using coordinates derived from the compliance force constants (Cij: the method being called CIV) are employed in QTAIM-DFA, for the establishment of the methodology to elucidate the nature of each HB in the multi-HBs. The dynamic nature of interactions with CIV is described as the “intrinsic dynamic nature of interactions”, since the coordinates corresponding to Cij are invariant to the choice of the coordinate system. Each HB in the multi-HBs of 1–3 are predicted to have the nature of CT-MC (molecular complex formation through charge transfer) appear at the regular closed shell region, which are stronger than each HB of the isomers of 1–3. The methodology to elucidate the nature of multi-HBs is well established, which employs the perturbed structures generated with CIV for QTAIM-DFA.
The intrinsic dynamic and static nature of the π···π interactions between the phenyl groups in proximity of helicenes 3–12 are elucidated with the quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA). The π···π interactions appear in C-*-C, H-*-H, and C-*-H, with the asterisks indicating the existence of bond critical points (BCPs) on the interactions. The interactions of 3–12 are all predicted to have a p-CS/vdW nature (vdW nature of the pure closed-shell interaction), except for 2Cbay-*-7Cbay of 10, which has a p-CS/t-HBnc nature (typical-HBs with no covalency). (See the text for definition of the numbers of C and the bay and cape areas.) The natures of the interactions are similarly elucidated between the components of helicene dimers 6:6 and 7:7 with QTAIM-DFA, which have a p-CS/vdW nature. The characteristic electronic structures of helicenes are clarified through the natures predicted with QTAIM-DFA. Some bond paths (BPs) in helicenes appeared or disappeared, depending on the calculation methods. The static nature of Ccape-*-Ccape is very similar to that of Cbay-*-Cbay in 9–12, whereas the dynamic nature of Ccape-*-Ccape appears to be very different from that of Cbay-*-Cbay. The results will be a guide to design the helicene-containing materials of high functionality.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.