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A series of acylsulfenyl iodides (RCOSI) were synthesized by the reactions of carbothioic acid group 11–16 element derivatives with iodine or N-iodosuccinimides in moderate to good yields.

Consecutive treatment of 2-(2-lithiophenyl)pyridine with chalcogen tetrachlorides (ChCl4; Ch = Se and Te) and KPF6 afforded the hexafluorophosphate salts of tris[2-(2-pyridyl)phenyl]selenonium [(pp...

The intrinsic dynamic and static nature of each HB in the multi-HBs between nucleobase pairs (Nu–Nu′) is elucidated with QTAIM dual functional analysis (QTAIM-DFA). Perturbed structures generated using coordinates derived from the compliance constants (Cii) are employed for QTAIM-DFA. The method is called CIV. Two, three, or four HBs are detected for Nu–Nu′. Each HB in Nu–Nu′ is predicted to have the nature of CT-TBP (trigonal bipyramidal adduct formation through charge transfer (CT)), CT-MC (molecular complex formation through CT), or t-HBwc (typical HB with covalency), while the vdW nature is predicted for the C–H⋯X interactions, for example. Energies for the formation of the pairs (ΔE) are linearly correlated with the total values of Cii−1 in Nu–Nu′. The total Cii−1 values are obtained by summing each Cii−1 value, similarly to the case of Ohm's law for the parallel connection in the electric resistance. The total ΔE value for a nucleobase pair could be fractionalized to each HB, based on each Cii−1 value. The perturbed structures generated with CIV are very close to those generated with the partial optimization method, when the changes in the interaction distances are very small. The results provide useful insights for better understanding DNA processes, although they are highly enzymatic.

In QTAIM dual-functional analysis, Hb(rc) is plotted versus Hb(rc) − Vb(rc)/2 for the interactions, where Hb(rc) and Vb(rc) are the total electron energy densities and potential energy densities, respectively, at the bond critical points (BCPs) on the interactions in question. The plots are analyzed by the polar (R, θ) coordinate representation for the data from the fully optimized structures, while those from the perturbed structures around the fully optimized structures are analyzed by (θp, κp). θp corresponds to the tangent line of the plot, and κp is the curvature; θ and θp are measured from the y-axis and y-direction, respectively. The normal and inverse behavior of interactions is proposed for the cases of θp > θ and θp < θ, respectively. The origin and the mechanism for the behavior are elucidated. Interactions with θp < θ are typically found, although seldom for [F–I-∗-F]−, [MeS-∗-TeMe]2+, [HS-∗-TeH]2+ and CF3SO2N-∗-IMe, where the asterisks emphasize the existence of BCPs in the interactions and where [Cl–Cl-∗-Cl]− and CF3SO2N-∗-BrMe were employed as the reference of θp > θ. The inverse behavior of the interactions is demonstrated to arise when Hb(rc) − Vb(rc)/2 and when the corresponding Gb(rc), the kinetic energy densities at BCPs, does not show normal behavior.

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 mixe...

The intrinsic dynamic and static natures of the E⋯E′ interactions at the 1,8-positions of 1-(MeE)–8-(MeE′)C10H6 [1a–1f (E ≠ E′) and 1g–1j (E = E′)] were elucidated with QTAIM-DFA, after structural determination of 1-(PhE)–8-(PhE′)C10H6 (3a–3f), where (E, E′: x) = (O, S: a), (O, Se: b), (O, Te: c), (S, Se: d), (S, Te: e), (Se, Te: f), (O, O: g), (S, S: h), (Se, Se: i) and (Te, Te: j) (χE ≥ χE′). While the AB structures are confirmed for 3a, 3b and 3d–3f, which consist of the np(E)⋯σ*(E′–CPh) interactions, the structure was BB for 3c, where the E–CR/E′–CR (R = Ph) bond is perpendicular to the naphthyl plane in A and it is placed on the plane in B. While the AB structures are determined by the p(E)–π(Ph) conjugations, the BB structure is by the crystal packing effect. The BA structure with np(E′)⋯σ*(E–CPh) was not detected. While the nature of a typical hydrogen bond with covalency was predicted for BB, AA and BA, with the CT-MC (molecular complex formation through charge transfer) nature for AB in 1e and 1f (R = Me for E–CR/E′–CR), the CT-MC nature was predicted for all conformers of 1j, for example. NBO analysis for 1a–1f revealed that the acceptor orbitals contribute much more than the donor orbitals and the order is σ*(O–CMe

The intrinsic dynamic and static nature of noncovalent Br-∗-Br interactions in neutral polybromine clusters is elucidated for Br4–Br12, applying QTAIM dual-functional analysis (QTAIM-DFA). The asterisk (∗) emphasizes the existence of the bond critical point (BCP) on the interaction in question. Data from the fully optimized structures correspond to the static nature of the interactions. The intrinsic dynamic nature originates from those of the perturbed structures generated using the coordinates derived from the compliance constants for the interactions and the fully optimized structures. The noncovalent Br-∗-Br interactions in the L-shaped clusters of the Cs symmetry are predicted to have the typical hydrogen bond nature without covalency, although the first ones in the sequences have the vdW nature. The L-shaped clusters are stabilized by the n(Br)→σ*(Br–Br) interactions. The compliance constants for the corresponding noncovalent interactions are strongly correlated to the E(2) values based on NBO. Indeed, the MO energies seem not to contribute to stabilizing Br4 (C2h) and Br4 (D2d), but the core potentials stabilize them, relative to the case of 2Br2, this is possibly due to the reduced nuclear–electron distances, on average, for the dimers.

The intrinsic dynamic and static nature of the non-covalent Br-*-Br interactions in the neutral polybromine clusters is elucidated for Br4–Br12, applying QTAIM dual functional analysis (QTAIM-DFA). The asterisk (*) emphasizes the existence of the bond critical point (BCP) on the interaction in question. Data from the fully optimized structures correspond to the static nature of interactions. The intrinsic dynamic nature is originated from those of the perturbed structures generated using the coordinates derived from the compliance constants for the interactions and the fully optimized structures. The non-covalent Br-*-Br interactions in the L-shaped clusters of the Cs symmetry are predicted to have the typical hydrogen bond nature without covalency, although the first ones in the sequences have the vdW nature. The L-shaped clusters are stabilized by the n(Br)->σ*(Br–Br) interactions. The compliance constants for the corresponding non-covalent interactions are strongly correlated to the E(2) values based on NBO. Indeed, the MO energies seem not contribute to stabilize Br4 (C2h) and Br4 (D2d), but the core potentials stabilize them, relative to the case of 2Br2, maybe due to the reduced nuclear-electron distances in the average for the dimmers.

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.

The dynamic and static nature of XH-*-π and YX-*-π in the coronene π-system (π(C24H12)) is elucidated by QTAIM dual functional analysis, where * emphasizes the presence of bond critical points (BCPs) in the interactions. The nature of the interactions is elucidated by analysing the plots of the total electron energy densities Hb(rc) versus Hb(rc) − Vb(rc)/2 [=(ħ2/8m)∇2ρb(rc)] for the interactions at BCPs, where Vb(rc) are the potential energy densities at the BCPs. The data for the perturbed structures around the fully optimized structures are employed for the plots in addition to those of the fully optimized structures. The plots are analysed using the polar coordinate of (R, θ) for the data of the fully optimized structures, while those containing the perturbed structures are analysed using (θp, κp), where θp corresponds to the tangent line of each plot and κp is the curvature. Whereas (R, θ) show the static nature, (θp, κp) represent the dynamic nature of the interactions. All interactions in X–H-*-π(C24H12) (X = F, Cl, Br and I) and Y–X-*-π(C24H12) (Y–X = F–F, Cl–Cl, Br–Br, I–I, F–Cl, F–Br and F–I) are classified by pure CS (closed shell) interactions and are characterized as having the vdW nature, except for X–H = F–H and Y–X = F–Cl, F–Br and F–I, which show the typical-HB nature without covalency. The structural features of the complexes are also discussed.

Invited for this month's cover picture is the group of Dr. Satoko Hayashi at Faculty of Systems Engineering and Chemistry at Wakayama University. The cover picture shows the linear Se(16) σ(16c–30e) interactions, illustrated by the molecular graph type on the optimized structure of the dicationic octamer of 1,5‐(diselena)cane. HOMO‐1 of ψ(462) is drawn on the structure, which is located predominantly on the Se atoms. The optimized structure is stable, due to the nice engagement between the (CH(2))(3) moieties. The contour maps of ρ(r) are also drawn on the molecular C (s) planes of the dicationic dimer and trimer to demonstrate clearly the existence of the interactions between Se atoms. Read the full text of their Full Paper at 10.1002/open.202100017.

Indirect one-bond nuclear spin-spin couplings between M and C [1 J(M,C)] in Me4 M, Me3 M- , Ph4 M, and Ph3 M- (M=Pb, Sn, Ge, Si, C) are analyzed with consideration of the relativistic effect and by employing Slater-type basis sets. The evaluated total values 1 JTL (M,C) reproduced the observed values with some systematic calculation errors. Fermi contact terms 1 JFC (M,C) contribute predominantly to 1 JTL (M,C) (≈99 %). A distinct relativistic effect on 1 J(Pb,C) is predicted for Me3 Pb- and Ph3 Pb- . The mechanisms for the distinct effect are elucidated by using the comparison between Me3 Pb- and Me4 Pb as an example. The contributions to 1 JFC (M,C) [or 1 JSD+FC (M,C), where SD denotes the spin-dipolar term] are decomposed into those of occupied orbitals and occupied-to-unoccupied transitions. The s-type lone-pair orbitals are demonstrated to contribute to the distinct relativistic effect on 1 J(Pb,C) of Me3 Pb- (and Ph3 Pb- ). The results are in sharp contrast to the cases of 1 J(M,C) for M atoms lighter than Pb, such as Si, and are explained by the s character of the M-C bonds. This treatment enables visualization and clear recognition the origin of the nuclear couplings for the species exhibiting a relativistic effect.

The nature ofE2X2σ(4c–6e) of theX-*-E-*-E-*-Xtype is elucidated for 1-(8-XC10H6)E–E(C10H6X-8′)-1′ [(1)E,X= S, Cl; (2) S, Br; (3) Se, Cl; (4) Se, Br] after structural determination of (1), (3) and (4), together with modelA[MeX---E(H)—E(H)---XMe (E= S and Se;X= Cl and Br)]. The quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA) is applied. The total electron energy densitiesHb(rc) are plottedversus Hb(rc) –Vb(rc)/2 for the interactions at the bond critical points (BCPs; *), whereVb(rc) show the potential energy densities at the BCPs. Data for the perturbed structures around the fully optimized structures are employed for the plots, in addition to those of the fully optimized structures. The plots were analysed using the polar coordinate (R, θ) representation of the data of the fully optimized structures. Data containing the perturbed structures were analysed by (θp, κp), where θpcorresponds to the tangent line of the plot and κpis the curvature. Whereas (R, θ) shows the static nature, (θp, κp) represents the dynamic nature of interactions.E-*-Eare all classified as shared shell (S) interactions for (1)–(4) and as weak covalent (Cov-w) in nature (S/Cov-w). The nature ofpureCS (closed shell)/typical-HB (hydrogen bond) with no covalency is predicted forE-*-Xin (1) and (3),regularCS/typical-HB nature with covalency is predicted for (4), and an intermediate nature is predicted for (2). The NBO energies evaluated forE-*-Xin (1)–(4) are substantially larger than those in modelAdue the shortened length at the naphthalene 1,8-positions. The nature ofE2X2of σ(4c–6e) is well elucidatedviaQTAIM-DFA.

Dynamic and static nature of intramolecular π-π interactions between ethylene moieties in diethenodihydronaphthanaphtalene (1 b) and derivatives (2 b–12 b) are elucidated by employing QTAIM-DFA (QTAIM dual functional analysis). During the course of the investigations, doubly degenerated bond paths were detected between carbon atoms in opposite benzene rings of dibenzo-derivative of 1 b with an etheno-bridge on the backside (11 b). It must be very curious, since one BP should correspond to an interaction between two carbon atoms. Intramolecular π-π interactions in 1 b–12 b are all classified by the pure CS (closed shell) interactions. The interactions between ethylene groups, with no substituents as in 1 b–8 b, are predicted to have the van der Waals (vdW) nature. Those for 9 b–12 b have the hydrogen bond (HB) nature with no covalency, where the ethylene moieties are included in one or two benzene ring(s), except for 10 b, if evaluated with MP2/6-311G(3d). The character in 10 b is close to the borderline area between the vdW and HB nature with no covalency, although should be the vdW type. The interactions in 2 b–12 b evaluated with MP2/6-311G(3d) are predicted to be somewhat stronger than the case with MP2/6-311G(d), as a whole.

The nature of EH2-*-π(C14H10) interactions (E = O, S, Se and Te) of an anthracene system was elucidated by applying QTAIM dual functional analysis (QTAIM-DFA) after clarification of the structural features with quantum chemical (QC) calculations. π-HB (hydrogen bond) interactions were detected for E = O, S, Se and Te, whereas π-EB (chalcogen bond) interactions were observed for E = O in (EH2)-*-π(C14H10), where the bond paths connected H in EH2 to C14H10 in π-HB, and they connected E in EH2 to C10H8 in π-EB. The QTAIM-DFA parameters of (R, θ) and (θp, κp) were evaluated for the interactions via analysing the plots of Hb(rc) versus Hb(rc) − Vb(rc)/2 for the interactions at the bond critical points. Data obtained from the perturbed structures around the fully optimized structures were employed for the plots, in addition to the fully optimized structures. Data obtained from the fully optimized structures were analysed using (R, θ), which corresponded to the static nature, and those obtained from the perturbed structures were analysed using (θp, κp), which represented the dynamic nature of the interactions, where θp corresponds to the tangent line of the plot and κp is the curvature. The θ and θp values are less than 90° for all the interactions examined, except for the iH-*-11C(π) interaction in TeH2-*-C14H10 (C1: IIBAtc), where iH is located closer to the centre of C14H10. Therefore, the interactions examined were predicted to have vdW nature, appeared in the pure-CS (closed shell) interaction region, although iH-*-11C(π) was predicted to have the pure-CS/typical-HB nature without covalency. Additionally, the π-HB interaction seems to be slightly stronger than π-EB in (OH2)-*-π(C14H10).

The intrinsic dynamic and static nature of G-*-E-*-Y σ(3c-4e) interactions was elucidated with the quantum theory of atoms in molecules dual functional analysis (QTAIM-DFA), employing

The intrinsic dynamic and static nature of intramolecular OH–*–π interactions is elucidated using a QTAIM dual functional analysis (QTAIM-DFA) after clarifying the structural features. Asterisks (*) are employed to emphasize the presence of bond critical points (BCPs) on the bond paths (BPs), which correspond to the interactions in question. Data from the fully optimized structures correspond to the static nature of the interactions. In our treatment, data from the perturbed structures, which are based around the fully optimized structure, are employed for the analysis in addition to those from the fully optimized structure, which represent the dynamic nature of the interaction. Seven intramolecular OH–*–C(π) interactions were detected in six-membered rings, with six BPs and BCPs for each, among the 72 conformers of the species examined here (1–15). The interactions are predicted to have a vdW or t-HBnc (typical hydrogen bonds with no covalency) nature, which appeared in the pure closed shell region. They appear to be stronger than the corresponding intermolecular interactions. Nine BPs with BCPs were also detected for the intramolecular O–*–X interactions (X = C(π) and H(π), joined to C(π)) in the 5–7-membered rings. The E(2) values of the interactions, as obtained by NBO, are discussed in relation to the stabilities of the conformers and the BPs with BCPs.

The nature of Br4σ(4c–6e) of the BBr-∗-ABr-∗-ABr-∗-BBr form is elucidated for SeC12H8(Br)SeBr---Br-Br---BrSe(Br)C12H8Se, the selenanthrene system, and the models with QTAIM dual functional analysis (QTAIM-DFA). Asterisks (∗) are employed to emphasize the existence of bond critical points on the interactions in question. Data from the fully optimized structure correspond to the static nature of interactions. In our treatment, data from the perturbed structures, around the fully optimized structure, are employed for the analysis, in addition to those from the fully optimized one, which represent the dynamic nature of interactions. The ABr-∗-ABr and ABr-∗-BBr interactions are predicted to have the CT-TBP (trigonal bipyramidal adduct formation through charge transfer) nature and the typical hydrogen bond nature, respectively. The nature of Se2Br5σ(7c–10e) is also clarified typically, employing an anionic model of [Br-Se(C4H4Se)-Br---Br---Br-Se(C4H4Se)-Br]−, the 1,4-diselenin system, rather than (BrSeC12H8)Br---Se---Br-Br---Br-Se(C12H8Se)-Br, the selenanthrene system.

The intrinsic dynamic and static nature of G–*–E–*–Y σ(3c–4e) interactions was elucidated with the quantum theory of atoms in molecules dual functional analysis (QTAIM-DFA), employing o-MenGCH2C6H4EY (MenG = Me2N and MeE; E = O, S, Se and Te; Y = F, Cl, Br, I, EMe and Me). Asterisks (*) are employed to emphasize the existence of bond critical points (BCPs) on the bond paths (BPs), corresponding to the interactions in question. Data from the fully optimized structure correspond to the static nature of interactions. The dynamic nature is called the intrinsic dynamic nature if the perturbed structures are generated using the coordinates derived from the compliance constants. Basis sets of the Sapporo-TZP type with diffusion functions are employed for the heteroatoms at the MP2 level. The noncovalent G–*–E interactions in GEY σ(3c–4e) are predicted to demonstrate van der Waals bonding to CT-TBP (trigonal bipyramidal adduct formation through charge transfer) nature, while the E–*–Y bonds have the covalent nature. Some E–F bonds show strong ionic character when G–*–E is predicted to be stronger than E–*–Y. The contributions of the CT terms to the G–*–E interactions, evaluated with NBO, are discussed in relation to the predicted nature. The E(2) values based on NBO are strongly correlated to the compliance constants for the G–*–E interactions if suitably treated separately.

The nature of halogen bonds of the Y-X-✶-π(C6 H6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual-functional analysis (QTAIM-DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond-critical points (BCPs) in the interactions in question. Total electron energy densities, Hb (rc ), are plotted versus Hb (rc )-Vb (rc )/2 [=(ħ(2) /8m)∇(2) ρb (rc )] for the interactions in QTAIM-DFA, in which Vb (rc ) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar (R, θ) coordinate for the data of fully optimized structures with (θp , κp ) for those that contained the perturbed structures; θp corresponds to the tangent line of the plot and κp is the curvature. Whereas (R, θ) corresponds to the static nature, (θp , κp ) represents the dynamic nature of the interactions. All interactions in Y-X-✶-π(C6 H6 ) are classified by pure closed-shell interactions and characterized to have vdW nature, except for Y-I-✶-π(C6 H6 ) (Y=F, Cl, Br) and F-Br-✶-π(C6 H6 ), which have typical hydrogen-bond nature without covalency. I-I-✶-π(C6 H6 ) has a borderline nature between the two. Y-F-✶-π(C6 H6 ) (Y=Br, I) were optimized as bent forms, in which Y-✶-π interactions were detected. The Y-✶-π interactions in the bent forms are predicted to be substantially weaker than those in the linear F-Y-✶-π(C6 H6 ) forms.

The nature of extended hypervalent interactions of the BE–*–AE–*–AE–*–BE type is elucidated for 1-(8-MeBEC10H6)AE–AE(C10H6BEMe-8′)-1′, (1 (AE, BE) = (S, S), 2 (S, Se), 3 (Se, S) and 4 (Se, Se)) and models A–D, BR2BE⋯(AR)AE–AE(AR)⋯BEBR2 (AR, BR = H and Me). QTAIM dual functional analysis, which we proposed recently, is applied to the analysis. Total electron energy densities Hb(rc) are plotted versus Hb(rc) − Vb(rc)/2 for the interactions at bond critical points (BCPs; *), where Vb(rc) show potential energy densities at BCPs. Data for the perturbed structures around the fully optimized structures are employed for the plots, in addition to those of the fully optimized ones. While the data for the fully optimized structures are analysed by the polar coordinate (R, θ) representation, those containing the perturbed structures are by (θp, κp): θp corresponds to the tangent line for the plot and κp is the curvature. While (R, θ) show the static nature, (θp, κp) represent the dynamic nature of interactions. All AE–*–AE interactions in 1–4 and models A–D are classified by the shard shell interactions and have the character of a weak covalent nature. The AE–*–BE interactions in 1–4 are all classified by the regular closed shell interactions. They are predicted to have the typical HB (hydrogen bond) nature with covalency for 1 and 2 but the nature of the molecular complex formation through CT for 3 and 4. The AE–*–BE interactions in models A–D are predicted to be weaker than those in 1–4.

The nature of the π–interactions in the 1 : 1 and 2 : 1 adducts of EH2 with the naphthalene π-system (E = O, S, Se and/or Te) is elucidated by applying QTAIM-DFA (QTAIM dual functional analysis). The H–*–π interactions are detected in EH2–*–π(C10H8) and (EH2)2–*–π(C10H8) for E = S, Se and Te, whereas E–*–π interactions are in OH2–*–π(C10H8), (OH2)2–*–π(C10H8) and HE–H–*–π(C10H8) (denoted by HHE–*–C10H8) (E = S, Se and Te). Asterisks * emphasize the existence of bond critical points (BCPs) on the interactions in question. Hb(rc) are plotted versus Hb(rc) − Vb(rc)/2 at the BCPs in QTAIM-DFA. Plots for the fully optimized structures are analyzed using the polar coordinate (R, θ) representation. Those containing the perturbed structures are by (θp, κp): θp corresponds to the tangent line of the plot and κp is the curvature. While (R, θ) describe the static nature, (θp, κp) represent the dynamic nature of interactions. The θ and θp values are less than 90° for all interactions in question, examined in this work, except for θp = 90.6° for HHTe–*–π(C10H8). Therefore, all interactions examined are classified by the pure-CS (closed shell) interactions and predicted to have vdW-nature, except for HHTe–*–π(C10H8), which should have the character of the typical HB-nature without covalency. The π–EB interaction in HHS–*–C10H8 is predicted to have the border character between the vdW-nature and the typical HB-nature without covalency, since θp = 89.8°. The nature of four interactions appeared between 2H in TeH2 and C10H8 in TeH2–*–π(C10H8) is also clarified well using QTAIM-DFA.

An extended hypervalent S4 σ(4c–6e) system was confirmed for the linear BS-∗-AS-∗-AS-∗-BS interaction in 1-(8-PhBSC10H6)AS–AS(C10H6BSPh-8′)-1′ (1) via high-resolution X-ray diffraction determination of electron densities. The presence of bond critical points (BCPs; ∗) on the bond paths confirms the nature and extent of this interaction. The recently developed QTAIM dual functional analysis (QTAIM-DFA) approach was also applied to elucidate the nature of the interaction. Total electron energy densities Hb(rc) were plotted versus Hb(rc) − Vb(rc)/2 for the interaction at the BCPs, where Vb(rc) represents the potential energy densities at the BCP. The results indicate that although the data for an interaction in the fully optimized structure corresponds to a static nature, the data obtained for the perturbed structures around it represent the dynamic nature of the interaction in QTAIM-DFA. The former classifies the interaction and the latter characterises it. Although AS-∗-AS in 1 is classified by a shared shell interaction and exhibits weak covalent character, AS-∗-BS is characterized as having typical hydrogen-bond nature with covalent properties in the region of the regular closed shell interactions. The experimental results are supported by matching theoretical calculations throughout, particularly for the extended hypervalent E4 σ(4c–6e) (E = S) interaction.

The nature of the transannular E-∗-E' interactions in neutral, radical cationic, and dicationic forms of cyclo-E(CH2CH2CH2)2E' (1) (E, E' = S, Se, Te, and O) (1, 1(•+), and 1(2+), respectively) is elucidated by applying QTAIM dual functional analysis (QTAIM-DFA). Hb(rc) are plotted versus Hb(rc) - Vb(rc)/2 for the data of E-∗-E' at BCPs in QTAIM-DFA, where ∗ emphasizes the existence of BCP. Plots for the fully optimized structures are analyzed by the polar coordinate (R, θ) representation. Those containing the perturbed structures are by (θp, κp): θp corresponds to the tangent line of the plot, and κp is the curvature. While (R, θ) describes the static nature, (θp, κp) represents the dynamic nature of interactions. The nature is well-specified by (R, θ) and (θp, κp). E-∗-E' becomes stronger in the order of 1 < 1(•+) < 1(2+), except for O-∗-O. While E-∗-E' (E, E' = S, Se, and Te) in 1(2+) are characterized as weak covalent bonds, except for S-∗-Te (MC nature through CT) and Se-∗-Te (TBP nature through CT), O-∗-E' seems more complex. The behavior of E-∗-E' in 1(2+) is very close to that of cyclo-E(CH2CH2CH2)E' (E, E' = S, Se, Te, and O), except for O-∗-O.

Atoms-in-molecules dual functional analysis (AIM-DFA) is applied to the E–E′ bonds (E, E′ = S and Se) in R-cystine (1) and the derivatives of 1, together with MeEE′Me. Hb(rc) are plotted versus Hb(rc) − Vb(rc)/2 at bond critical points (BCPs), where Hb(rc) − Vb(rc)/2 = (ħ2/8m)∇2ρb(rc). The plots are analyzed by the polar coordinate (R, θ) representation. Data of perturbed structures around the fully optimized structures are also plotted in this treatment. Perturbed structures are generated using NIV (normal coordinates of internal vibrations). Each plot for an interaction with data of a fully optimized and four perturbed structures gives a curve, which supplies important information. It is expressed by (θp, κp): θp corresponds to the tangent line for the plot measured from the y-direction and κp is the curvature. While (R, θ) correspond to the static nature of interactions, (θp, κp) represent the dynamic nature. The behavior of the E–E′ bonds is well described by (R, θ) and (θp, κp).

An extended hypervalent S

Indirect one-bond nuclear spin-spin couplings between M and C [

The dynamic and static nature of extended hypervalent interactions of the BE···AE···AE···BE type are elucidated for four center–seven electron interactions (4c–7e) in the radical cationic dimers (1·+) and 4c–6e in the dicationic dimers (12+) of 1,5-(dichalcogena)canes (2: AE(CH2CH2CH2)2BE: AE, BE = S, Se, Te, and O). The quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA) is applied for the analysis. Total electron energy densities Hb(rc) are plotted versus Hb(rc) – Vb(rc)/2 [= (ℏ2/8m)∇2ρb(rc)] at bond critical points (BCPs) of the interactions, where Vb(rc) values show potential energy densities at BCPs. Data from the fully optimized structures correspond to the static nature of the interactions. Those from the perturbed structures around the fully optimized ones are also plotted, in addition to those of the fully optimized ones, which represent the dynamic nature of interactions. The BE···AE–AE···BE interactions in 12+ are stronger than the corresponding ones in 1·+, respectively. ...

The nature of the E-*-E' bonds in neutral, monoanionic, monocationic, and dicationic forms of HEE'H (1), MeEE'Me (2), and cyclo-1,2-EE'(CH2)3 (3) (E, E' = O, S, Se, Te) is investigated by applying AIM (atoms-in-molecules method) dual functional analysis. Hb(rc) are plotted versus Hb(rc) – Vb(rc)/2 for the data of E-*-E' at bond critical points (BCPs) of fully optimized structures and perturbed structures around the fully optimized ones. Plots for the fully optimized structures are analyzed by the polar coordinate (R, θ) representation. The (θp, κp) parameters are derived from those of the perturbed structures: θp corresponds to the tangent line of each plot, and κp is the curvature. While (R, θ) correspond to the static nature, (θp, κp) represent the dynamic nature of interactions. The nature of E-*-E' in the neutral and charged species is classified by comparing their θ and θp values with those of the standard interactions as a reference. Data for E-*-E' in the neutral forms of 1–3 appear in the shared-shell (SS) region (180° < θ), except for MeS-*-TeMe (2c), which does in the regular closed-shell (CS) region (90° < θ < 180°). The E–E' bonds in the monoanionic forms of 1–3 become much longer and weakened. Therefore, data of the monoanionic forms appear in the regular CS. On the other hand, the strengths of E-*-E' in the mono- and dicationic forms are almost equal to those in the neutral forms of 1–3 in the plots, irrespective of the shorter E-*-E' lengths in the cationic forms, relative to the neutral forms.

To systematically elucidate molecular and electronic structures of aromatic selenoic acid salts and their heavier congeners, they were synthesized by reacting selenoic, selenothioic, and diselenoic...

The relativistic effects on absolute magnetic shielding tensors [σ(Z: Z = Te, Se and S)] are explicitly evaluated for various tellurium, selenium and sulfur species using the DFT(BLYP)-GIAO method. Calculations of σ(Te), σ(Se) and σ(S) are performed under the spin–orbit ZORA relativistic (Rlt-so) and nonrelativistic (Non) conditions with the Slater-type basis sets of the quadruple zeta all electron with four polarization functions (QZ4Pae). Structures optimized at the MP2 level under nonrelativistic conditions are employed for the evaluations. While the range of the relativistic effects on the total shielding tensors for Te (Δσt(Te)Rlt-so = σt(Te)Rlt-so − σd+p(Te)Non) is predicted to be −55 to 658 ppm, that for Δσt(S) is predicted to be 5 to 32 ppm, except for Me2SBr2 (TBP), where Δσt(S)Rlt-so = −29 ppm. The range for Δσt(Se) is 2 to 153 ppm. The magnitudes of the relativistic effects on σt(Te), σt(Se) and σt(S) are about 25 : 5 : 1. The applicability of σt(Te)Rlt-so to analyze δ(Te)obsd is also examined, mainly with the OPBE//OPBE method under the spin–orbit ZORA relativistic conditions with QZ4Pae, in addition to the above method.

The nature of E

Dynamic and static behavior of the interactions in the EH2 adducts of a benzene π-system (E = O, S, Se and Te) is elucidated by applying QTAIM-DFA (QTAIM dual functional analysis). Two types of H-*-π and E-*-π interactions are detected in the adducts, where the asterisk (*) emphasizes the existence of the bond critical point (BCP) on the interaction in question. Total electron energy densities Hb(rc) are plotted versus Hb(rc) -Vb(rc)/2 [=(ℏ(2)/8m)∇(2)ρb(rc)] at BCPs in QTAIM-DFA, where Vb(rc) are the potential energy densities at BCPs. Data from the fully optimized structures are analyzed by polar (R, θ) coordinate representation. Each plot for an interaction, containing data from the perturbed structures with those of the fully optimized one, shows a specific curve, which provides important information. The plot is expressed by (θp, κp): θp corresponds to the tangent line for the plot and κp is the curvature. θ and θp are measured from the y-axis and y-direction, respectively. Moreover, (R, θ) corresponds to the static nature, (θp, κp) represents the dynamic nature of interactions. While θ classifies the interaction in question, θp characterizes it. Both values are less than 90° for all H-*-π and E-*-π interactions examined in this study; therefore, they are all classified by the pure closed-shell interactions and predicted to have the character of vdW nature. However, it is suggested that E-*-π has the nature of the stronger interaction than the case of H-*-π for dynamic behavior in the same species evaluated at the MP2 and M06-2X levels. The nature of the interactions is well analyzed and specified by applying QTAIM-DFA.