Synthesis and structural characterisation of rhodium hydride complexes bearing N-heterocyclic carbene ligands

Susie Douglas, John P Lowe, Mary F Mahon, John E Warren, Michael K Whittlesey

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Addn. of excesses of N-heterocyclic carbenes (NHCs) IEt2Me2, IiPr2Me2 or ICy (IEt2Me2 = 1,3-diethyl-4,5-dimethylimidazol-2-ylidene; IiPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene; ICy = 1,3-dicyclohexylimidazol-2-ylidene) to [HRh(PPh3)4] (1) affords an isomeric mixt. of [HRh(NHC)(PPh3)2] [NHC = IEt2Me2 (cis-/trans-2), IiPr2Me2 (cis-/trans-3), ICy (cis-/trans-4)] and [HRh(NHC)2(PPh3)] [NHC = IEt2Me2(cis-/trans-5), IiPr2Me2 (cis-/trans-6), ICy (cis-/trans-7)]. Thermolysis of 1 with the aryl substituted NHC, 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (IMesH2), affords the bridging hydrido phosphido dimer, [{(PPh3)2Rh}2(micro -H)(micro -PPh2)] (8), which is also the reaction product formed in the absence of carbene. When the Rh precursor was changed from 1 to [HRh(CO)(PPh3)3] (9) and treated with either IMes (1,3-dimesitylimidazol-2-ylidene) or ICy, the bis-NHC complexes trans-[HRh(CO)(IMes)2] (10) and trans-[HRh(CO)(ICy)2] (11) were formed. In contrast, the reaction of 9 with IiPr2Me2 gave [HRh(CO)(IiPr2Me2)2] (cis-/trans-12) and the unusual unsym. dimer, [(PPh3)2Rh(micro -CO)2Rh(IiPr2Me2)2] (13). Trans-3, 8, 10 and 13 were structurally characterized.
Original languageEnglish
Pages (from-to)5027-5035
Number of pages9
JournalJournal of Organometallic Chemistry
Volume690
Issue number23
Publication statusPublished - 2005

Keywords

  • Molecular structure (of rhodium hydride complexes with N-heterocyclic carbene imidazolylidene ligands)
  • Diastereomers (geometric
  • mol structure rhodium hydride heterocyclic carbene imidazolylidene ligand
  • PREP (Preparation) (prepn. and structure of rhodium hydride complexes with N-heterocyclic carbene imidazolylidene ligands)
  • PRP (Properties)
  • RCT (Reactant)
  • rhodium hydride heterocyclic carbene imidazolylidene ligand prepn structure
  • crystal structure rhodium hydride heterocyclic carbene imidazolylidene ligand prepn
  • RACT (Reactant or reagent) (nitrogen
  • prepn. and structure of rhodium hydride complexes with N-heterocyclic carbene imidazolylidene ligands)
  • five-membered-ring
  • Crystal structure
  • Heterocyclic compounds Role
  • Carbene complexes Role
  • SPN (Synthetic preparation)

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