A Rare Uranyl(VI)–Alkyl Ate Complex [Li(DME)_1.5]₂[UO₂(CH₂SiMe₃)₄] and Its Comparison with a Homoleptic Uranium(VI)–Hexaalkyl

Insights into trans‐Ligand and Spin‐Orbit Effects on Electronic Structure and Ligand NMR Shifts in Transition‐Metal Complexes

“…Extension to ligand effects on 13 Cs hifts in organometallic complexes:A lthough ligand effects tend to be magnified for hydride 1 Hs hifts, due to the particularly large SO shieldingsi nvolved, [2,3] it is appropriate to widen our view to other nuclei as well. [43] Indeed, previous calculations have already provided indications of such trans ligand effects, even for the 13 Cs hifts in organomercury complexes:f or example, in ref. [39] we obtained s SO = À15 ppm for the methyl carbon atoms in Hg(CH 3 ) 2 ,b ut only s SO = À5ppm for CH 3 HgCl.…”

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

“…12,13 The latter was oxidized in situ to U(CH 2 SiMe 3 ) 6 , which was characterized using 13 C and 1 H NMR spectroscopies, accompanied by relativistic DFT calculations of NMR chemical shifts. 16 In each uranium example, an octahedral geometry was observed, which is perhaps not surprising, as significant f-orbital participation in bonding tends to favor an octahedral geometry. 17 In contrast, d orbital involvement in Th-C bonding is expected to be more significant than f orbital participation, 18,19 and therefore the observation of a trigonal prismatic structure should be more likely for this element relative to the other actinides.…”

“…This resonance is shifted notably downfield from the corresponding 13 C-ipso shifts in related Ti, Zr, and Hf aryl complexes (which typically appear between 183 and 198 ppm), 20 which can be attributed to a substantial spin-orbit (SO)-induced deshielding (d SO 4 30 ppm) of s-bonded carbon nuclei to f 0 actinide center. 16,21 The other 13 C aryl signals are observed at 136.9, 126.6 and 125.2 ppm, and are assignable to ortho, meta and para carbon atoms of the phenyl ring, respectively.…”

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

“…Temperaturedependent magnetic susceptibility data of Yb(Cp BIG ) 2 revealed diamagnetism, indicating stable divalent ytterbium. Temperaturedependent 151 Eu Mössbauer effect spectroscopic examination of Eu(Cp BIG ) 2 was examined over the temperature range 93-215 K, and the hyperfine and dynamical properties of the Eu II species were discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal Xray data at 203 K. The large difference in these two values was Reprinted with permission from Ref.…”

“…Computational analyses showed that the 5f uranium character in the U C -bond is larger in the hexaalkyl complex U(CH 2 SiMe 3 ) 6 , which was also reflected in the most deshielded 13 C NMR shift observed in diamagnetic mononuclear compounds. Thus, the comparison of computed and experimental 13 C NMR data provided an important additional method for the analysis of covalent bonding and 5f-orbital participation in uranium(VI) complexes [151].…”