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).