Catalysis with Chalcogen Bonds

Abstract

Herein, we introduce catalysts that operate with chalcogen bonds. Compared to conventional hydrogen bonds, chalcogen bonds are similar in strength but more directional and hydrophobic, thus ideal for precision catalysis in apolar solvents. For the transfer hydrogenation of quinolines and imines, rate enhancements well beyond a factor of 1000 are obtained with chalcogen bonds. Better activities with deeper σ holes and wider bite angles, chloride inhibition and correlation with computed anion binding energies are consistent with operational chalcogen bonds. Comparable to classics, such as 2,2'-bipyrroles or 2,2'-bipyridines, dithieno[3,2-b;2',3'-d]thiophenes (DTTs), particularly their diimides, but also wide-angle cyclopentadithiazole-4-ones are identified as privileged motifs to stabilize transition states in the focal point of the σ holes on their two co-facial endocyclic sulfur atoms.

Digging the Sigma‐Hole of Organoantimony Lewis Acids by Oxidation

“…[14] We note in passing that the use of the electron deficient tetrachlorocatecholate ligands in 5 and 6 is necessary to stabilize the + Voxidation state of these compounds. [3c] Using 1 Ha nd 19 FNMR spectroscopy,w ef ound that 1, 2,a nd 3 do not interact to any measurable extent with Ph 3 PO in CDCl 3 .B y contrast, the 1 H, 31 P, and 19 FNMR spectra of stiboranes 4, 5, and 6 undergo drastic changes upon addition of Ph 3 PO.Inthe case of 4,weobserved that the 1:1adduct Ph 3 PO!SbPh 3 Cat is in rapid equilibrium with 4 and Ph 3 PO at NMR concentrations.I ncremental addition of 4 to as olution of Ph 3 PO induces ap rogressive downfield shift of the 31 PNMR resonance consistent with increasing concentrations of the 1:1a dduct. [3c] Using 1 Ha nd 19 FNMR spectroscopy,w ef ound that 1, 2,a nd 3 do not interact to any measurable extent with Ph 3 PO in CDCl 3 .B y contrast, the 1 H, 31 P, and 19 FNMR spectra of stiboranes 4, 5, and 6 undergo drastic changes upon addition of Ph 3 PO.Inthe case of 4,weobserved that the 1:1adduct Ph 3 PO!SbPh 3 Cat is in rapid equilibrium with 4 and Ph 3 PO at NMR concentrations.I ncremental addition of 4 to as olution of Ph 3 PO induces ap rogressive downfield shift of the 31 PNMR resonance consistent with increasing concentrations of the 1:1a dduct.…”

Electroactive Nanoporous Metal Oxides and Chalcogenides by Chemical Design

“…59 This lack of understanding exists despite our ability to, on the one hand, synthesize well-defined metal chalcogenide structures, and on the other hand, use such materials with open architectures as catalysts in a variety of photo- and electrochemical applications. 60 …”

Unveiling the Sulfur–Sulfur Bridge: Accurate Structural and Energetic Characterization of a Homochalcogen Intermolecular Bond

“…In parallel, non-covalent chalcogen-bond interactions have attracted much attention because of the fundamental role they play in different fields such as catalysis, [8] drug design, [1] self-assembly processes, [9] and crystal packing. [10] Understanding the mechanisms at the basis of these technological processes requires the characterization of the directionality,strength, and nature of such interactions [11] as well as acomprehensive analysis of their competition with other noncovalent bonds,a lso taking into account the tuning of these properties by different environments.I nt his respect, in analogy to the halogen bond [12] the sulfur atom can act either as achalcogen bond donor (due to a s- [13,14] or p-hole [13,15] on sulfur) or as acceptor (because of al one-pair on sulfur, as in thioethers [14] ).…”