Singlet Diradical Character of an Oxidized Ruthenium Trithiolate: Electronic Structure and Reactivity

Abstract

All alone: The ground state of the oxidized, reactive intermediate [Ru(dppbt)3]+ (dppbt=2‐diphenylphosphinothiaphenolate) is calculated to be a singlet diradical. The unpaired electrons in the π* orbitals are delocalized over the metal atom and the ligand sulfur atoms. The relative orientation of the half‐occupied orbitals inhibits disulfide formation and favors addition of unsaturated hydrocarbons across adjacent sulfur atoms.

Homogeneous ligand-centered hydrogen evolution and hydrogen oxidation : exploiting redox non-innocence to drive catalysis.

“…Furthermore, the B3LYP functional was used to obtain broken symmetry solutions. 125,[140][141][142][143] Frequency calculations were performed for all optimized stationary points to ensure they were true minima. Transition states (TS) were determined using the…”

“…Dithiolenes are well-known to exhibit noninnocent redox behavior, affording ligand-centered reductions and oxidations. 11,12,143,153,161 This ligand non-innocence offers extremely reactive thiyl radicals. As detailed in ( Figure 9A) the facial arrangement of the PS chelates in [ReL 3 ] n enforces a symmetry preferred interligand addition route.…”

“…As detailed in ( Figure 9A) the facial arrangement of the PS chelates in [ReL 3 ] n enforces a symmetry preferred interligand addition route. 143,153 The lone-pair p-type orbitals on S1 and S2 are coplanar, and the frontier molecular orbitals include an occupied out-of-phase combination supporting the necessary geometry needed to interact with the *-orbital of alkenes, and a vacant in-phase combination, which is anti-bonding with respect to the metal d-orbital, providing the proper symmetry to interact with the orbital of alkenes, or in the case of H 2 , the σ orbital. (10) S (2) Figure 12) (see appendix for additional data).…”

Carbon-sulfur bond formation/cleavage reactions of metal-stabilized thiyl radicals by electrochemical and chemical methods.

“…35 The diradical generated can react with various alkenes at rate sufficient to prevent observation of the intermediate. The reactivity is proven by reactions with alkenes ranging from simple alkenes, like ethylene, to bulkier, bridged alkenes, like norbomene.…”

Carbon-sulfur bond formation via alkene addition to an oxidized ruthenium-thiolate.

“…48 The DFT work will be the focus of Holly Frye's Thesis. Based on the DFT studies, 1c is best described as having a singlet diradical ground state.…”