Rare Earth- and Uranium-Mesoionic Carbenes: A New Class of f-Block Carbene Complex Derived from an N-Heterocyclic Olefin

Research output: Contribution to journalArticle

  • External authors:
  • John Seed
  • Matthew Gregson
  • Ashley Wooles

Abstract

Neutral mesoionic carbenes (MICs) have emerged as an important class of carbene, however they are found only in the free form or ligated to a few d-block ions. Here, we report unprecedented f-block MIC complexes [M(N'')3{CN(Me)C(Me)N(Me)CH}] (M = U, Y, La, Nd; N'' = N(SiMe3)2). These complexes were prepared by a formal 1,4-proton migration reaction when the metal-triamides [M(N'')3] were treated with the N-heterocyclic olefin H2C=C(NMeCH)2, which constitutes a new, general way to prepare MIC complexes. Quantum chemical calculations on the 5f3 uranium(III) complex suggest the presence of a U=C donor-acceptor bond, composed of a MIC→U σ-component and a U(5f)→MIC(2p) π-back-bond, but for the d0f0 Y and La and 4f3 Nd congeners only MIC→M σ-bonding is found. Considering the generally negligible π-acidity of MICs, this is surprising and highlights that greater consideration should possibly be given to recognising MICs as potential π-acid ligands when coordinated to reducing metals.

Bibliographical metadata

Original languageEnglish
JournalAngewandte Chemie - International Edition
Early online date18 Jul 2017
DOIs
Publication statusPublished - 2017

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