Molybdenum sulphide clusters as redox-active supports for low-valent uranium

Abstract

The preparation of an actinide substituted cubane cluster, (Cp*3Mo3S4)Cp*UI2, and its reduced derivatives are reported.

Molecular Models of Atomically Dispersed Uranium at MoS2 Surfaces Reveal Cooperative Mechanism of Water Reduction

“…Analysis of the crude reaction mixture by 1 H NMR spectroscopy reveals a pattern of signals similar to that of 1 , with significant downfield shifts in the resonances corresponding to the protons of the Cp* ligand bound to uranium and the Cp* ligands of the thiomolybdate cluster (Figures and S1). The chemical shift of the Mo-bound Cp* signal of the product resembles the value reported for the one-electron oxidized assembly, (Cp* 3 Mo 3 S 4 )­Cp*UI, suggesting formation of an oxidized product. The proposed oxidation of the heterometallic assembly was accompanied by formation of ∼0.5 equiv of H 2 (Figures S1 and S2; quantification of H 2 in solution was determined by integration vs mesitylene as an internal standard).…”

“…To interrogate the mechanism of water reduction at U@MoS 2 , we investigated the reactivity of the reduced uranium cluster (Cp* 3 Mo 3 S 4 )­Cp*U ( 1 ) previously reported by our group . We present this compound as a molecular analogue of single U atom deposited on the basal plane of MoS 2 nanosheets (U@MoS 2 ).…”

“…The extent of the interaction between the uranium center with the hemicubane thiomolybdate cluster is an important metric to examine in the structure of 2 . Prior work from our group has indicated that the distance between the trisulfide surface of the metalloligand and the uranium center is sensitive to the oxidation state of the cluster (e.g., (Cp* 3 Mo 3 S 4 ) Cp*UI , U–S surf = 1.6623(9) Å; (Cp* 3 Mo 3 S 4 ) Cp*UI 2 , U–S surf = 1.8554(6) Å; (Cp* 3 Mo 3 S 4 ) Cp*U­(NPh) 2 , U–S surf = 2.0187(15) Å), suggesting extensive electronic communication between the low-valent uranium and its support . Similarly, several reports of uranium on MoS 2 surfaces suggest that their formation is accompanied by a charge transfer between the uranium and the surface sulfur centers.…”

“…Anhydrous styrene oxide was purchased from Sigma-Aldrich, deoxygenated three times, and stored over 3 Å molecular sieves prior to its use. [(Cp* 3 Mo 3 S 4 )­UCp*] and N 3 Mes (Mes = 2,4,6-trimethylphenyl) were synthesized following established procedures.…”

“…Intrigued by the unique reactivity of uranium atoms deposited on redox active surfaces, our group has been investigating the coordination chemistry of a hemicubane thiomolybdate cluster, (Cp* 3 Mo 3 S 4 ), with low-valent uranium (Figure ). We view these heterometallic clusters as models for low-valent uranium ions deposited on the basal plane (i.e., 001 surface) of MoS 2 . Our team found that the coordination of the trisulfide face of the metalloligand (Cp* 3 Mo 3 S 4 ) with Cp*UI 2 (THF) 3 is associated with a charge transfer process, in which uranium is oxidized and the thiomolybdate assembly is reduced.…”