Lanthanide/actinide differentiation with sterically encumbered N-heterocyclic carbene ligands

Polly L. Arnold, Zoe R. Turner, Anne I. Germeroth, Ian J. Casely, Ronan Bellabarba, Robert P. Tooze

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

A study is reported on the relative stability of trivalent bis(ligand) complexes of the form [M(LR)2N''] for trivalent group 3, lanthanide and actinide cations, using the sterically demanding N-heterocyclic carbene ligand LR = [OCMe2CH2{CNCH2CH2NR}] (R = iPrLP, Mes LM, Dipp LD; N'' = N(SiMe3)2). For the small YIII cation (r6-coord = 1.040 Å) and the smallest LR, R = iPr, mono, bis, and tris(LP) complexes can be made; [Y(LP)2N''] and [Y(LP)3] have been characterised. For the larger ligands, LM and LD, only the mono(LR) complexes [Y(LM)N''2] and [Y(LD)N''2] can be made. For the larger CeIII (r6-coord = 1.15 Å), mono(LR) and bis(LR) complexes [Ce(LM)N''2], [Ce(LD)N''2], [Ce(LM)2N''], and [Ce(LD)2N''] can be made; structural characterisation of the latter two confirm the high degree of steric congestion. The new complex [U(LM)N''2] has also been isolated. Despite the very similar radii of CeIII and UIII (r6-coord = 1.165 Å), the complexes [U(LR)2N''] cannot be isolated; a surprising display of the difference between the 4f and 5f metal series. However, the six-coordinate, bis(ligand) UIV complexes can readily be isolated if smaller ancillary ligands are used; [U(LM)2I2] and [U(LD)2I2] have been fully, including structurally, characterised.

Original languageEnglish
Pages (from-to)6808-6814
Number of pages7
JournalDalton Transactions
Volume39
Issue number29
Early online date4 Jun 2010
DOIs
Publication statusPublished - 7 Aug 2010

Keywords / Materials (for Non-textual outputs)

  • CRYSTAL-STRUCTURE
  • ETHYLENE OLIGOMERIZATION
  • COORDINATION CHEMISTRY
  • TRANSITION-METALS
  • NHC CATALYSTS
  • COMPLEXES
  • POLYMERIZATION
  • REACTIVITY
  • URANIUM
  • BOND

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