Twist-chair conformation of the tetraoxepane ring remains unchanged in tetraoxaspirododecane diamines

Abstract

A detailed structural analysis has been performed for N,N′‐bis(4‐chlorophenyl)‐7,8,11,12‐tetraoxaspiro[5.6]dodecane‐9,10‐diamine, C20H22Cl2N2O4, (I), N,N′‐bis(2‐fluorophenyl)‐7,8,11,12‐tetraoxaspiro[5.6]dodecane‐9,10‐diamine, C20H22F2N2O4, (II), and N,N′‐bis(4‐fluorophenyl)‐7,8,11,12‐tetraoxaspiro[5.6]dodecane‐9,10‐diamine, C20H22F2N2O4, (III). The seven‐membered ring with two peroxide groups adopts a twist‐chair conformation in all three compounds. The lengths of the C—N and O—O bonds are slightly shorter than the average statistical values found in the literature for azepanes and 1,2,4,5‐tetraoxepanes. The geometry analysis of compounds (I)–(III), the topological analysis of the electron density at the (3, −1) bond critical points within Bader's quantum theory of `Atoms in molecules' (QTAIM) and NBO (natural bond orbital) analysis at the B3LYP/6‐31G(d,2p) level of theory showed that there are nO→σ*(C—O), nN→σ*(C—O) and nO→σ*(C—N) stereoelectronic effects. The molecules of compounds (I) and (III) are packed in the crystals as zigzag chains due to strong N—H…O and C—H…O hydrogen‐bond interactions, whereas the molecules of compound (II) form chains in the crystals bound by N—H…O, C—H…π and C—H…O contacts. All these data show that halogen atoms and their positions have a minimal effect on the geometric parameters, stereoelectronic effects and crystal packing of compounds (I)–(III), so that the twist‐chair conformation of the tetraoxepane ring remains unchanged.

Multicomponent Assembly of Bicyclic Aza-peroxides Catalyzed by Samarium Complexes and Their Cytotoxic Activity

“…Indeed, in 11a , the lp O3 → σ* O5–C4 and lp O5 → σ* C4–O3 interactions amount to 14.81 and 13.86 kcal/mol, respectively, while those in 6a are 15.9 and 14.6 kcal/mol for the chair-boat-chair conformer and 13.6 and 7.5 kcal/mol for the twist-chair-chair conformer. In the O–O–C segment, like in 4-methyl-10-(5-methyl-1,2-oxazol-3-yl)-1-(propan-2-yl)-7,8,12,13-tetraoxa-10-azaspiro[5.7]­tridecane, the lone pairs of O2, O6, O3, and O5 oxygen atoms weakly interact with the antibonding σ*-orbitals of the O3–C4, O5–C4, O2–C1, and O6–C7 bonds, respectively (Table SI-2). As shown in the literature, , C–O bonds have more pronounced acceptor properties (∼40%) than O–C bonds in the σ C–H → σ* X–Y and n O → σ* X–Y interactions because of orbital polarization toward carbon.…”

“…Analysis of the crystal structures included in the Cambridge Structural Database (CSD Release 2020.0) showed that the homopolar O−O bond length in the cyclic peroxides varies in the range from 1.45 to 1.49 Å, which is in line with the data obtained for the peroxide bonds of compounds 6a and 11a (Table SI-1). The endocyclic C1−N11 and C7−N11 bonds in 6a and 11a are markedly shorter than the C−N bonds in 11-methyl-11-azabicyclo [5,3,1]undecan-4one; 35 The deviation of bond lengths in structures 6a and 11a from typical values, like in our previous studies, 36,37 is attributable to stereoelectronic interactions (between the nitrogen lone pair (lp) of the electron and the antibonding sigma (σ*) orbitals of the C−O bonds; between the oxygen lp and the σ*-orbitals of C−N bonds; between the oxygen lp and the σ*-orbitals of the C−O bonds; and between the oxygen lp and the σ*-orbitals of the O−C bonds).…”

“…The deviation of bond lengths in structures 6a and 11a from typical values, like in our previous studies, , is attributable to stereoelectronic interactions (between the nitrogen lone pair (lp) of the electron and the antibonding sigma (σ*) orbitals of the C–O bonds; between the oxygen lp and the σ*-orbitals of C–N bonds; between the oxygen lp and the σ*-orbitals of the C–O bonds; and between the oxygen lp and the σ*-orbitals of the O–C bonds).…”

Computational identification of potential modulators of heme-regulated inhibitor (HRI) for pharmacological intervention against sickle cell disease

“…This information is crucial for predicting reactivity in chemical reactions, especially in drug development [ 40 ]. The computed dipole moment (ω) quantifies the separation of positive and negative charges in a molecule, providing insight into its overall polarity [ 41 ]. C3 displayed the highest dipole moment at 0.256, indicating substantial charge separation and heightened molecular polarity.…”

Meta-Hybrid Density Functional Theory Prediction of the Reactivity, Stability, and IGM of Azepane, Oxepane, Thiepane, and Halogenated Cycloheptane

“…Five-membered heterocyclic substituents containing a single group of 16 heteroatoms were taken into consideration to investigate the influence of heteroatom rings on quantum molecular properties such as dipole moment, frontier molecular orbital (MO), polarizabilities, and energetic stability for these studied systems. More so, insight from refs ( 12 − 15 ) has contributed significantly to this work.…”