Intrinsic Dynamic Nature of Neutral Hydrogen Bonds Elucidated with QTAIM Dual Functional Analysis: Role of the Compliance Force Constants and QTAIM-DFA Parameters in Stability.

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 (H2 Se-✶-HSeH; ✶=bond critical point), t -HBnc ( typical -HBs with no covalency: HI-✶-HI), t -HBwc ( t -HBs with covalency: H2 C=O-✶-HI), CT-MC [molecular complex formation through charge transfer (CT): H2 C=O-✶-HF], and CT-TBP (trigonal bipyramidal adduct formation through CT: H3 N-✶-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 Δ E , is well correlated with Cij (Δ E × Cij =constant value of -165.64), and the QTAIM parameters, although a few deviations were detected.