Thorium-ligand multiple bonds via reductive deprotection of a trityl group.

Reaction of [Th(I)(NR2)3] (R = SiMe3) (2) with KECPh3 (E = O, S) affords the thorium chalcogenates, [Th(ECPh3)(NR2)3] (3, E = O; 4, E = S), in moderate yields. Reductive deprotection of the trityl group from 3 and 4 by reaction with KC8, in the presence of 18-crown-6, affords the thorium oxo complex, [K(18-crown-6)][Th(O)(NR2)3] (6), and the thorium sulphide complex, [K(18-crown-6)][Th(S)(NR2)3] (7), respectively. The natural bond orbital and quantum theory of atoms-in-molecules approaches are employed to explore the metal-ligand bonding in 6 and 7 and their uranium analogues, and in particular the relative roles of the actinide 5f and 6d orbitals

Thorium-ligand multiple bonds via reductive deprotection of a trityl group

Reaction of [Th(I)(NR2)3] (R = SiMe3) (2) with KECPh3 (E = O, S) affords the thorium chalcogenates, [Th(ECPh3)(NR2)3] (3, E = O; 4, E = S), in moderate yields. Reductive deprotection of the trityl group from 3 and 4 by reaction with KC8, in the presence of 18-crown-6, affords the thorium oxo complex, [K(18-crown-6)][Th(O)(NR2)3] (6), and the thorium sulphide complex, [K(18-crown-6)][Th(S)(NR2)3] (7), respectively. The natural bond orbital and quantum theory of atoms-in-molecules approaches are employed to explore the metal-ligand bonding in 6 and 7 and their uranium analogues, and in particular the relative roles of the actinide 5f and 6d orbitals

Synthesis of Uranium–Ligand Multiple Bonds by Cleavage of a Trityl Protecting Group

Addition of KSCPh₃ to [U­(NR₂)₃] (R = SiMe₃) in tetrahydrofuran, followed by addition of 18-crown-6, results in formation of the U­(IV) sulfide, [K­(18-crown-6)]­[U­(S)­(NR₂)₃] (<b>1</b>) and Gomberg’s dimer. Similarly, addition of KOCPh₃ to [U­(NR₂)₃] in tetrahydrofuran, followed by addition of 18-crown-6, results in formation of the U­(IV) oxide, [K­(18-crown-6)]­[U­(O)­(NR₂)₃] (<b>3</b>). Also observed in this transformation are the triphenylmethyl anion, [K­(18-crown-6)­(THF)₂]­[CPh₃] (<b>5</b>), and the U­(IV) alkoxide, [U­(OCPh₃)­(NR₂)₃] (<b>4</b>)

Reversible Chalcogen-Atom Transfer to a Terminal Uranium Sulfide

The reaction of elemental S or Se with [K­(18-crown-6)]­[U­(S)­(NR₂)₃] (<b>1</b>) results in the formation of the new uranium­(IV) dichalcogenides [K­(18-crown-6)]­[U­(η²-S₂)­(NR₂)₃] (<b>2</b>) and [K­(18-crown-6)]­[U­(η²-SSe)­(NR₂)₃] (<b>5</b>). The further addition of elemental S to <b>2</b> results in the formation of [K­(18-crown-6)]­[U­(η³-S₃)­(NR₂)₃] (<b>3</b>). Complexes <b>2</b>, <b>3</b>, and <b>5</b> can be reconverted into <b>1</b> via the addition of R₃P (R = Et, Ph), concomitant with the formation of R₃PE (E = S, Se)

Synthesis, Electrochemistry, and Reactivity of the Actinide Trisulfides [K(18-crown-6)][An(η³‑S₃)(NR₂)₃] (An = U, Th; R = SiMe₃)

The reaction of [Th­(I)­(NR₂)₃] (R = SiMe₃) with [K­(18-crown-6)]₂[S₄] results in the formation of [K­(18-crown-6)]­[Th­(η³-S₃)­(NR₂)₃] (<b>2</b>). Oxidation of <b>2</b>, or its uranium analogue, [K­(18-crown-6)]­[U­(η³-S₃)­(NR₂)₃] (<b>1</b>), with AgOTf, in an attempt to generate an [S₃]^•– complex, results in the formation of [K­(18-crown-6)]­[An­(OTf)₂(NR₂)₃] (<b>3</b>, An = U; <b>4</b>, An = Th) as the only isolable products. These results suggest that the putative [S₃]^•– ligand is only weakly coordinating and can be easily displaced by nucleophiles

Synthesis, Electrochemistry, and Reactivity of the Actinide Trisulfides [K(18-crown-6)][An(η³‑S₃)(NR₂)₃] (An = U, Th; R = SiMe₃)

The reaction of [Th­(I)­(NR₂)₃] (R = SiMe₃) with [K­(18-crown-6)]₂[S₄] results in the formation of [K­(18-crown-6)]­[Th­(η³-S₃)­(NR₂)₃] (<b>2</b>). Oxidation of <b>2</b>, or its uranium analogue, [K­(18-crown-6)]­[U­(η³-S₃)­(NR₂)₃] (<b>1</b>), with AgOTf, in an attempt to generate an [S₃]^•– complex, results in the formation of [K­(18-crown-6)]­[An­(OTf)₂(NR₂)₃] (<b>3</b>, An = U; <b>4</b>, An = Th) as the only isolable products. These results suggest that the putative [S₃]^•– ligand is only weakly coordinating and can be easily displaced by nucleophiles

Synthesis of Uranium–Ligand Multiple Bonds by Cleavage of a Trityl Protecting Group

Addition of KSCPh₃ to [U­(NR₂)₃] (R = SiMe₃) in tetrahydrofuran, followed by addition of 18-crown-6, results in formation of the U­(IV) sulfide, [K­(18-crown-6)]­[U­(S)­(NR₂)₃] (<b>1</b>) and Gomberg’s dimer. Similarly, addition of KOCPh₃ to [U­(NR₂)₃] in tetrahydrofuran, followed by addition of 18-crown-6, results in formation of the U­(IV) oxide, [K­(18-crown-6)]­[U­(O)­(NR₂)₃] (<b>3</b>). Also observed in this transformation are the triphenylmethyl anion, [K­(18-crown-6)­(THF)₂]­[CPh₃] (<b>5</b>), and the U­(IV) alkoxide, [U­(OCPh₃)­(NR₂)₃] (<b>4</b>)

Synthesis of Terminal Monochalcogenide and Dichalcogenide Complexes of Uranium Using Polychalcogenides, [E_<i>n</i>]^2– (E = Te, <i>n</i> = 2; E = Se, <i>n</i> = 4), as Chalcogen Atom Transfer Reagents

Reaction of KH with elemental tellurium, in the presence of 18-crown-6, results in the formation of the ditelluride, [K­(18-crown-6)]₂[Te₂] (<b>1</b>), in good yield. Similarly, reaction of KH with elemental selenium, in the presence of 18-crown-6, results in the formation of [K­(18-crown-6)]₂­[Se₄] (<b>4</b>). Both <b>1</b> and <b>4</b> are capable of chalcogen atom transfer to U­(III). For example, addition of 0.5 equiv or 1 equiv of [K­(18-crown-6)]₂­[Te₂] (<b>1</b>) to [U­(NR₂)₃] (R = SiMe₃) or [U­(I)­(NR₂)₃], respectively, results in the formation of the new U­(IV) tellurides, [K­(18-crown-6)]­[U­(Te)­(NR₂)₃] (<b>2</b>), and [K­(18-crown-6)]­[U­(η²-Te₂)­(NR₂)₃] (<b>3</b>), in moderate yields, while addition of 0.5 equiv of [K­(18-crown-6)]₂­[Se₄] (<b>4</b>) to [U­(NR₂)₃] results in the formation of the U­(IV) diselenide, [K­(18-crown-6)]­[U­(η²-Se₂)­(NR₂)₃] (<b>5</b>). Interestingly, <b>5</b> can be converted into the monoselenide [K­(18-crown-6)]­[U­(Se)­(NR₂)₃] (<b>6</b>) via reaction with Ph₃P