Synthesis, structure and bonding of hexaphenyl thorium(IV): observation of a non-octahedral structure

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.We report herein the synthesis of the first structurally characterized homoleptic actinide aryl complexes, [Li(DME)(3)](2)[Th(C6H5)(6)] (1) and [Li(THF)(12-crown-4)](2)[Th(C6H5)(6)] (2), which feature an anion possessing a regular octahedral (1) or a severely distorted octahedral (2) geometry. The solid-state structure of 2 suggests the presence of pseudo-agostic ortho C-H center dot center dot center dot Th interactions, which arise from sigma(C-H) -> Th(5f) donation. The non-octahedral structure is also favoured in solution at low temperatures.DFG, EXC 314, Unifying Concepts in Catalysi

Oxo Ligand Substitution in a Cationic Uranyl Complex: Synergistic Interaction of an Electrophile and a Reductant.

Reaction of [U(VI)O2(dppmo)2(OTf)][OTf] (dppmo = Ph2P(O)CH2P(O)Ph2) with 4 equiv of Ph3SiOTf and 2 equiv of Cp2Co generates the U(IV) complex U(IV)(OTf)4(dppmo)2 (1), as a yellow-green crystalline solid in 83% yield, along with Ph3SiOSiPh3 and [Cp2Co][OTf]. This reaction proceeds via a U(IV) silyloxide intermediate, [U(IV)(OSiPh3)(dppmo)2(OTf)2][OTf] (2), which we have isolated and structurally characterized. Similarly, reaction of [U(VI)O2(TPPO)4][OTf]2 (TPPO = Ph3PO) with 6 equiv of Me3SiOTf and 2 equiv of Cp2Co generates the U(IV) complex, [Cp2Co][U(IV)(OTf)5(TPPO)2] (3), as a yellow-green crystalline solid in 76% yield, concomitant with formation of Me3SiOSiMe3, [Ph3POSiMe3][OTf], and [Cp2Co][OTf]. Complexes 1 and 3 have been fully characterized, including analysis by X-ray crystallography. The conversion of [U(VI)O2(dppmo)2(OTf)][OTf] and [U(VI)O2(TPPO)4][OTf]2 to complexes 1 and 3, respectively, represents rare examples of well-defined uranyl oxo ligand substitution

Synthesis, structure and bonding of hexaphenyl thorium(IV): observation of a non-octahedral structure.

We report herein the synthesis of the first structurally characterized homoleptic actinide aryl complexes, [Li(DME)3]2[Th(C6H5)6] (1) and [Li(THF)(12-crown-4)]2[Th(C6H5)6] (2), which feature an anion possessing a regular octahedral (1) or a severely distorted octahedral (2) geometry. The solid-state structure of 2 suggests the presence of pseudo-agostic ortho C-H···Th interactions, which arise from σ(C-H) → Th(5f) donation. The non-octahedral structure is also favoured in solution at low temperatures

Reductive Silylation of the Uranyl Ion with Ph₃SiOTf

The reaction of 2 equiv of Ph₃SiOTf with UO₂(dbm)₂(THF) (dbm = <i>O</i>C­(Ph)­CHC­(Ph)<i>O</i>) and UO₂(^Aracnac)₂ (^Aracnac = Ar<i>N</i>C­(Ph)­CHC­(Ph)<i>O</i>; Ar = 3,5-^tBu₂C₆H₃) results in the formation of U­(OSiPh₃)₂(dbm)₂(OTf) (<b>1</b>) and [U­(OSiPh₃)₂(^Aracnac)₂]­[OTf] (<b>2</b>), respectively, in good yield

Perturbation of the O-U-O Angle in Uranyl by Coordination to a 12-Membered Macrocycle.

Reaction of [UO2Cl2(THF)2]2 (THF = tetrahydrofuran) with 2 equiv of (H)N4 ((H)N4 = 2,11-diaza[3,3](2,6) pyridinophane) or (Me)N4 ((Me)N4 = N,N'-dimethyl-2,11-diaza[3,3](2,6) pyridinophane), in MeCN, results in the formation of UO2Cl2((R)N4) (R = H; 1; Me, 2), which were isolated as yellow-orange solids in good yields. Similarly, reaction of UO2(OTf)2(THF)3 with (H)N4 in MeCN results in the formation of UO2(OTf)2((H)N4) (3), as an orange powder in 76% yield. Finally, reaction of UO2(OTf)2(THF)3 with (Me)N4 in THF results in the formation of [UO2(OTf)(THF)((H)N4)][OTf] (4), as an orange powder in 73% yield. Complexes 1-4 were fully characterized, including characterization by X-ray crystallography. These complexes exhibit the smallest O-U-O bond angles measured to date, ranging from 168.2(3)° (for 2) to 161.7(5)° (for 4), a consequence of an unfavorable steric interaction between the oxo ligands and the macrocycle backbone. A Raman spectroscopic study of 1-4 reveals no correlation between O-U-O angle and the U═O νsym mode. However, complexes 1 and 2 do feature lower U═O νsym modes than complexes 3 and 4, which can be rationalized by the stronger donor strength of Cl(-) versus OTf(-). This observation suggests that the identity of the equatorial ligands has a greater effect on the U═O νsym frequency than does a change in O-U-O angle, at least when the changes in the O-U-O angles are small