Emergence of comparable covalency in isostructural cerium(iv)– and uranium(iv)–carbon multiple bonds

Abstract

Against expectations the covalency in a cerium(iv)–carbon multiple bond interaction is essentially as covalent as the uranium(iv) analogue.

Computational analysis of M–O covalency in M(OC6H5)4 (M = Ti, Zr, Hf, Ce, Th, U)

“…[33][34][35] Cerium is unique in the lanthanide series in having a readily accessible tetravalent oxidation state, and our results show similarities in the covalent nature of the Ce(OC6H5)4 and U(OC6H5)4. Two previous studies 34,35 use QTAIM metrics to report a covalency trend of U > Ce > Th and our results support this result, based on the metal contributions to bonding (Figure 3). This trend can be attributed to the f orbital contribution in π bonding, as the d orbital participation is similar, particularly for Ce and U.…”

Thorium–phosphorus triamidoamine complexes containing Th–P single- and multiple-bond interactions

“…This desire stems not only from a need to develop our knowledge and understanding of actinide bonding at a fundamental level45678, but also because of potential applications in nuclear waste clean-up which might utilize extraction methods that exploit covalency differences in metal-ligand bonding9. Because actinide-ligand multiple bonds arguably contain the greatest opportunities to probe covalency101112, in recent years in addition to numerous oxo complexes12 there has been intensive progress in uranium-carbene13141516171819, -imido202122232425262728, -nitride29303132, -phosphinidene/-arsinidene/-arsenido33343536 and -chalcogenido (S, Se, Te) chemistry37383940. This work demonstrates the wide range of multiply bonded ligands that can be stabilised at uranium with appropriate supporting ligands, and also that softer, heavier main group element centres can be stabilised as well as relatively hard first-row elements such as C, N and O.…”

“…However, to be verified this hypothesis requires a greater range of complexes to be prepared and compared, but progress in thorium-ligand multiple bonding pales when compared with uranium. For example, under ambient conditions there are only a handful of each class of structurally authenticated formal Th=C carbene134445, Th=N imido464748 and terminal Th=O oxo or Th=E···K (E=O, S, Se, Te) complexes495051 known; where thorium–phosphorus multiple bonds are concerned, they are conspicuous by their absence outside of cryogenic matrix isolation experiments52. Indeed, of fewer than thirty crystallographically authenticated thorium–phosphorus complexes in the Cambridge Structural Database53 seven are phosphanides54555657585960, three are polyphosphides6162, one is a phosphinidiide54, a term we use to indicate its bridging nature, and the remainder are phosphine derivatives; a dithorium-phosphinidiide complex [{Th(η 5 -C 5 Me 5 ) 2 (OMe)} 2 (μ-PH)] (ref.…”

Formation of a Ce(IV) Oxo Complex via Inner Sphere Nitrate Reduction

“…17 Also of note is the Ce(IV) methanediide complex, [Ce(BIPM TMS )(ODipp) 2 ] (BIPM TMS = C(PPh 2 NSiMe 3 ) 2 ; Dipp = C 6 H 3 -2,6-i Pr 2 ), reported by Liddle and co-workers. 18,19 This paucity of lanthanide examples has been rationalized by the mismatch in the energies of the metal and ligand frontier orbitals, which results in poor orbital overlap. [20][21][22] However, recent XAS studies have demonstrated that the 4f orbitals can participate in cerium-ligand bonding, at least for the Ce(IV) oxidation state, suggesting that some covalency within lanthanide-ligand bonding is possible.…”