A complete series of uranium(iv) complexes with terminal hydrochalcogenido (EH) and chalcogenido (E) ligands E = O, S, Se, Te.

We here report the synthesis and characterization of a complete series of terminal hydrochalcogenido, U-EH, and chalcogenido uranium(iv) complexes, U≡E (with E = O, S, Se, Te), supported by the (Ad,MeArOH)3tacn (1,4,7-tris(3-(1-adamantyl)-5-methyl-2-hydroxybenzyl)-1,4,7-triazacyclononane) ligand system. Reaction of H2E with the trivalent precursor [((Ad,MeArO)3tacn)U] (1) yields the corresponding uranium(iv) hydrochalcogenido complexes [((Ad,MeArO)3tacn)U(EH)] (2). Subsequent deprotonation of the terminal hydrochalcogenido species with KN(SiMe3)2, in the presence of 2.2.2-cryptand, gives access to the uranium(iv) complexes with terminal chalcogenido ligands [K(2.2.2-crypt)][((Ad,MeArO)3tacn)U≡E] (3). In order to study the influence of the varying terminal chalogenido ligands on the overall molecular and electronic structure, all complexes were studied by single-crystal X-ray diffractometry, UV/vis/NIR, electronic absorption, and IR vibrational spectroscopy as well as SQUID magnetometry and computational analyses (DFT, MO, NBO).

Metathesis of a UV imido complex: a route to a terminal UV sulfide.

Herein, we report the synthesis and characterisation of the first terminal uranium(v) sulfide and a related UV trithiocarbonate complex supported by sterically demanding tris(tert-butoxy)siloxide ligands. The reaction of the potassium-bound UV imido complex, [U(NAd){OSi(OtBu)3}4K] (4), with CS2 led to the isolation of perthiodicarbonate [K(18c6)]2[C2S6] (6), with concomitant formation of the UIV complex, [U{OSi(OtBu)3}4], and S[double bond, length as m-dash]C[double bond, length as m-dash]NAd. In contrast, the reaction of the UV imido complex, [K(2.2.2-cryptand)][U(NAd){OSi(OtBu)3}4] (5), with one or two equivalents of CS2 afforded the trithiocarbonate complex, [K(2.2.2-cryptand)][U(CS3){OSi(OtBu)3}4] (7), which was isolated in 57% yield, with concomitant elimination of the admantyl thiocyanate product, S[double bond, length as m-dash]C[double bond, length as m-dash]NAd. Complex 7 is likely formed by fast nucleophilic addition of a UV terminal sulfide intermediate, resulting from the slow metathesis reaction of the imido complex with CS2, to a second CS2 molecule. The addition of a solution of H2S in thf (1.3 eq.) to 4 afforded the first isolable UV terminal sulfide complex, [K(2.2.2-cryptand)][US{OSi(OtBu)3}4] (8), in 41% yield. Based on DFT calculations, triple-bond character with a strong covalent interaction is suggested for the U-S bond in complex 7.

Correction: Inner-sphere vs. outer-sphere reduction of uranyl supported by a redox-active, donor-expanded dipyrrin.

[This corrects the article DOI: 10.1039/C6SC02912D.].