Synthesis and luminescence studies of mono- and C-3-symmetric, tris(ligand) complexes of Sm(III), Y(III) and Eu(III) with sulfur-bridged binaphtholate ligands

L S Natrajan, A J Blake, C Wilson, J A Weinstein, P L Arnold, Polly Arnold

Research output: Contribution to journalArticlepeer-review

Abstract

A series of trivalent mono- and tris(ligand) lanthanide complexes of a sulfur-bridged binaphthol ligand [1,1'-S(2-HOC10H4Bu2t- 3,6)(2)] H2LSN, have been prepared and characterised both structurally and photophysically. The H2LSN ligand provides an increased steric bulk and offers an additional donor atom (sulfur) as compared with 1,1'-binaphthol (BINOL), a ligand commonly used to complex Lewis acidic lanthanide catalysts. Reaction of the diol H2LSN with [Sm{N(SiMe3)(2)}(3)] affords silylamido- and amino-derivatives [Sm(L-SN){N(SiMe3)(2)}{HN-(SiMe3)(2)}] and the crystallographically characterised [Sm(L-SN){N(SiMe3)(2)}(thf)(2)] with different degrees of structural rigidity, depending on the presence of coordinating solvents. The binaphthyl groups of the LSN ligand act as sensitisers of the metal centred emission, which is observed for the Eu(III) and Sm(III) complexes studied. We have therefore sought to use emission spectroscopy as a non-invasive technique to monitor a monomer-dimer equilibrium in these complexes. A dramatic difference between the emission properties of the unreactive dimeric Sm(III) aryloxide complex, the solvated monomeric analogues and the amido adduct demonstrated the potential use of such a technique. For a few representative lanthanides (Ln = Sm, Eu and Y) the reaction of the dilithium salt Li2LSN with either [Ln{N(SiMe3)(2)}(3)] or [LnCl(3)(thf)(3)] affords only the homoleptic complex [Li(S)(3)][LnL(3)(SN)] ( S = thf or diethyl ether); we report the structural characterisation of the Sm complex. However, the reactions of this dipotassium salt K2LSN with [Sm{N(SiMe3)(2)}(3)] or [SmCl3(thf)(3)] give only [(SmLN)-N-SN(SiMe3)(2)], or intractable mixtures respectively, in which no (tris) binaphtholate is observed. The only isolable lanthanide-L-SN halide adduct so far is [(YbLI)-I-SN(thf)].

Original languageEnglish
Pages (from-to)3748-3755
Number of pages8
JournalDalton Transactions
Issue number21
DOIs
Publication statusPublished - 2004

Keywords

  • EARTH-METAL COMPLEXES
  • STRUCTURAL-CHARACTERIZATION
  • LANTHANIDE COMPLEXES
  • CRYSTAL-STRUCTURES
  • ORGANOLANTHANIDE CHEMISTRY
  • POLYMERIZATION CATALYSTS
  • NAPHTHYL CHROMOPHORES
  • AGOSTIC RIGIDITY
  • ENERGY-TRANSFER
  • SCHIFF-BASE

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