N‐Thiophosphorylthioureas RNHC(S)NHP(S)(OiPr)₂ as an Excellent Platform for Studying the Synergy between Hydrogen‐Hydrogen Bonding and Other Families of Non‐Covalent Interactions

Abstract

A family of thiourea based derivatives, RNHC(S)NHP(S)(OiPr)2 [R = Ph (YEZNUN), 2‐MeC6H4 (AQOYAH), 2,5‐Me2C6H3 (WARREO), 2,6‐Me2C6H3 (GUJGUO), 2,4,6‐Me3C6H2 (AQOYEL), PhNH (QORXUR), 1‐naphthyl (MOWPEU)], has been studied to understand the synergy between dihydrogen and other (non)conventional non‐covalent interactions. It was established that all monomers are stabilized through intramolecular dihydrogen C–H···H–C interactions. Additionally, C–H···π interactions are noted in AQOYAH, WARREO, and MOWPEU; N–H···O interactions in AQOYAH, and WARREO; C–H···S interactions in GUJGUO, YEZNUN, and AQOYEL; N–H···S interactions in GUJGUO, AQOYEL, MOWPEU, and YEZNUN; and N–H···N interactions in QORXUR. The crystal structures of all the thioureas are further stabilized by the most pronounced intermolecular C–H···H–C interactions followed by N–H···S and C–H···S with the formation of centrosymmetric R22(8) dimers. These non‐covalent interactions are augmented by the π···π stacking in YEZNUN and MOWPEU; C–H···π in WARREO, GUJGUO, AQOYEL and MOWPEU; N–H···π in QORXUR. The synergy between intra‐ and intermolecular C–H···H–C and other types of non‐covalent interactions lead to the extraordinary stability of these systems as indicated by the ETS‐NOCV Scheme Although the London dispersion forces cover ≈ 70–80 % of the overall C–H···H–C stabilization, the covalent‐like charge delocalization based on depletion of electron charge from the σ(C–H) orbitals to the inter‐atomic H···H region contributes notably up to 15 %.

Formation of active species from ruthenium alkylidene catalysts—an insight from computational perspective

“…Particularly, ΔE dispersion is extremely significant at absolute level; it is −141 kJ mol −1 for 2 and − 144 kJ mol −1 for 1 ( Table 2). It is in accord with the recent findings which highlight that bulky substituents might lead to enhancement of the molecular stability since their London dispersion donating properties might easily outweigh the corresponding steric (Pauli/kinetic) repulsion [59][60][61][62][63][64]. In the forthcoming paragraphs, electron density reorganization channels due to formation of various types of non-covalent interactions are identified and discussed in detail.…”

“…The former involves charge transfer from the lone pair of chlorine to the empty σ*(C-H), whereas the latter consist of donation from σ(C-H) to the empty π* of phenyl ring. Additionally, homopolar dihydrogen close contacts CH … HC lead to the two ways charge delocalization channels σ(C-H)➔ σ*(C-H) (and vice-versa) [61][62][63][64]. They all amount to ΔE orb (4 + 5 + 6) = −14 kJ mol −1 (Fig.…”

Structural versatility of the quasi-aromatic Möbius type zinc(ii)-pseudohalide complexes – experimental and theoretical investigations

“…In 2, the cation is a doubly charged centrosymmetric dinuclear structure with two Zn II [57][58][59][60][61] study, that the seven-membered rings in 1-3 constitute a quasi-aromatic Möbius-type motif, though the absolute magnitude of such p-delocalization is notably weaker than in the corresponding cadmium-based analogs. 24,27 Bulkiness of the ligands (L) are found not only to amplify London dispersion stabilization, 24,27,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] but also inuence the magnitude of quasi-p-delocalization (of Möbius-type) through modi-cation of the polarity of Zn-L bonding.…”

“…The prevalence of the DE disp term is consistent with recent ndings, which rediscover the importance of London dispersion forces in small and sizeable species. 24,27,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] In 3 the [Zn(NCS) 4 ] 2À anion sticks very strongly (DE int ¼ À193.21 kcal mol À1 ) to two neighboring stacked [Zn(NCS)L II ] + units primarily through electrostatic forces (75.3% of the overall stabilization) (Fig. 5).…”

“…7). It demonstrates the two-folded role of bulky substituents: they are not only dispersion donors, [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] but they also lead to amplication of the 7-MR twist (and enhanced quasiaromaticity). Previously only the former feature has been recognized.…”