Hydrolytic cleavage of both CS2 carbon–sulfur bonds by multinuclear Pd(II) complexes at room temperature

Abstract

Developing homogeneous catalysts that convert CS and COS pollutants into environmentally benign products is important for both fundamental catalytic research and applied environmental science. Here we report a series of air-stable dimeric Pd complexes that mediate the facile hydrolytic cleavage of both CS carbon-sulfur bonds at 25 °C to produce CO and trimeric Pd complexes. Oxidation of the trimeric complexes with HNO regenerates the dimeric starting complexes with the release of SO and NO. Isotopic labelling confirms that the carbon and oxygen atoms of CO originate from CS and HO, respectively, and reaction intermediates were observed by gas-phase and electrospray ionization mass spectrometry, as well as by Fourier transform infrared spectroscopy. We also propose a plausible mechanistic scenario based on the experimentally observed intermediates. The mechanism involves intramolecular attack by a nucleophilic Pd-OH moiety on the carbon atom of coordinated µ-OCS, which on deprotonation cleaves one C-S bond and simultaneously forms a C-O bond. Coupled C-S cleavage and CO release to yield [(bpy)Pd(µ-S)](NO) (bpy, 2,2'-bipyridine) provides the thermodynamic driving force for the reaction.

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles

“…The in situ transformation of Pd species has also been found in various reactions. 349 For instance, Jiang et al have reported the application of trinuclear Pd clusters for the conversion of CS 2 into CO 2 in the presence of HNO 3 at room temperature. As shown in Figure 67 , the mononuclear Pd(II) complex first transformed into binuclear Pd complex, with further cleavage of the C–S bond in the CS 2 molecules, leading to the formation of CO 2 .…”

“…(c) Overall reaction of the conversion of CS 2 to CO 2 in HNO 3 . Adapted with permission from ref ( 349 ). Copyright 2017 Macmillan Publishers Limited, part of Springer Nature.…”

Evolution of Isolated Atoms and Clusters in Catalysis

“…The presence of metal clusters is usually confirmed by spectroscopy or mass spectrometry techniques. For example, Jiang and colleagues have isolated Pd 3 clusters coordinated with ligands that formed during Pd-catalyzed cleavage of both CS 2 carbon-sulfur bonds in the presence of HNO 3 [37]. The crystalline structure of the complex indicates that two S atoms are coordinated to Pd atoms in a bridged conformation, suggesting that the structure of the in situ-formed metal clusters interacts with the reactants and/or intermediates.…”

Cleavage of Carbon Disulfide by n‐Propyldiphenylphosphine and Nickel(II) Bromide

“…As ar esult, transition-metal complexes that activate carbon disulfide have been extensively studied. [10][11][12][13][14] The dissociation of carbond isulfide is also used to produce carbon monosulfide, CS, via photolysis, thermolysis, or other types of discharge methods. Carbon monosulfide has been widely studied in its highly reactive gaseous state, thoughi ts short lifetime makes it difficult to study.C arbon monosulfide, like carbon monoxide, has been shown to have an affinity for transition-metalc enters, resulting in the formation of transition-metal thiocarbonyl compounds.…”