C-C-Bindungsknüpfung durch reduktive Kupplung von CS2 an Uran zur Bildung von Tetrathiooxalat- und Ethylentetrathiolatkomplexen

Carbon-Carbon Bond Forming Reactions Promoted by Aluminyl and Alumoxane Anions: Introducing the Ethenetetraolate Ligand

[K{Al(NON^Dipp )}]₂ (NON^Dipp =[O(SiMe₂ NDipp)₂ ]^2- , Dipp=2,6-iPr₂ C₆ H₃ ) reacts with CS₂ to afford the trithiocarbonate species [K(OEt₂ )][Al(NON^Dipp )(CS₃ )] 1 or the ethenetetrathiolate complex, [K{Al(NON^Dipp )(S₂ C)}]₂ [3]₂ . The dimeric alumoxane [K{Al(NON^Dipp )(O)}]₂ reacts with carbon monoxide to afford the oxygen analogue of 3, [K{Al(NON^Dipp )(O₂ C)}]₂ [4]₂ containing the hitherto unknown ethenetetraolate ligand, [C₂ O₄ ]^4- .

Terminal Uranium(V/VI) Nitride Activation of Carbon Dioxide and Carbon Disulfide: Factors Governing Diverse and Well-Defined Cleavage and Redox Reactions

The reactivity of terminal uranium(V/VI) nitrides with CE₂ (E=O, S) is presented. Well-defined C=E cleavage followed by zero-, one-, and two-electron redox events is observed. The uranium(V) nitride [U(Tren^TIPS )(N)][K(B15C5)₂ ] (1, Tren^TIPS =N(CH₂ CH₂ NSiiPr₃ )₃ ; B15C5=benzo-15-crown-5) reacts with CO₂ to give [U(Tren^TIPS )(O)(NCO)][K(B15C5)₂ ] (3), whereas the uranium(VI) nitride [U(Tren^TIPS )(N)] (2) reacts with CO₂ to give isolable [U(Tren^TIPS )(O)(NCO)] (4); complex 4 rapidly decomposes to known [U(Tren^TIPS )(O)] (5) with concomitant formation of N₂ and CO proposed, with the latter trapped as a vanadocene adduct. In contrast, 1 reacts with CS₂ to give [U(Tren^TIPS )(κ² -CS₃ )][K(B15C5)₂ ] (6), 2, and [K(B15C5)₂ ][NCS] (7), whereas 2 reacts with CS₂ to give [U(Tren^TIPS )(NCS)] (8) and "S", with the latter trapped as Ph₃ PS. Calculated reaction profiles reveal outer-sphere reactivity for uranium(V) but inner-sphere mechanisms for uranium(VI); despite the wide divergence of products the initial activation of CE₂ follows mechanistically related pathways, providing insight into the factors of uranium oxidation state, chalcogen, and NCE groups that govern the subsequent divergent redox reactions that include common one-electron reactions and a less-common two-electron redox event. Caution, we suggest, is warranted when utilising CS₂ as a reactivity surrogate for CO₂ .

Insights into the mechanism of reaction of [(C5Me5)2Sm(II)(thf)2] with CO2 and COS by DFT studies

Reaction mechanisms for the oxidative reactions of CO(2) and COS with [(C(5)Me(5))(2)Sm] have been investigated by means of DFT methods. The experimental formation of oxalate and dithiocarbonate complexes is explained. Their formation involve the samarium(III) bimetallic complexes [(C(5)Me(5))(2)Sm-CO(2)-Sm(C(5)Me(5))(2)] and [(C(5)Me(5))(2)Sm-COS-Sm(C(5)Me(5))(2)] as intermediates, respectively, ruling out radical coupling for the formation of the oxalate complex.