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Further investigations into tetrahedral M 4 L 6 cage complexes containing guest anions: new structures and NMR spectroscopic studies

Tidmarsh, Ian S. ; Taylor, Brian F. ; Hardie, Michaele J. ; Russo, Luca ; Clegg, William ; Ward, Michael D.

New Journal of Chemistry, 2009, Vol.33(2), pp.366-375 [Rivista Peer Reviewed]

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  • Titolo:
    Further investigations into tetrahedral M 4 L 6 cage complexes containing guest anions: new structures and NMR spectroscopic studies
  • Autore: Tidmarsh, Ian S. ; Taylor, Brian F. ; Hardie, Michaele J. ; Russo, Luca ; Clegg, William ; Ward, Michael D.
  • Note di contenuto: A series of ligands L Ph , L naph and L anth , which contain two bidentate pyrazolyl–pyridine termini separated by an aromatic (1,2-phenyl, 2,3-naphthyl or 2,3-anthracenyl, respectively) spacer have been used to prepare tetrahedral cage complexes of the form [M 4 L 6 ]X n , in which a bis-bidentate bridging ligand spans each of the six edges of the M 4 tetrahedron and one anion is bound in the central cavity. Several new examples have been structurally characterised, including an example with a new ligand (L anth ), the first example with a second-row transition metal ion [Cd( ii )], and the first example of a cage containing a dianionic guest (hexafluorosilicate). The series of structurally similar Co( ii ) complexes [Co 4 L 6 (BF 4 )](BF 4 ) 7 (L = L Ph , L naph and L anth ) have been examined in detail by NMR spectroscopy. The 1 H NMR spectra are highly shifted between −110 and +90 ppm, but the spectra can be completely assigned by correlation of measured T 1 relaxation times with distances of the protons in the complexes from the paramagnetic Co( ii ) centres. 1 H DOSY measurements have been used to estimate diffusion constants which confirm the structural integrity of the cages in solution, and 19 F DOSY measurements on the anions show that (i) the trapped [BF 4 ] − anion diffuses at the same rate as the cage superstructure surrounding it, indicating that it is trapped inside the cage cavity; and (ii) the ‘free’ [BF 4 ] − anions have diffusion rates consistent with substantial retardation due to ion-pairing with the 7+ complex cation.
  • Fa parte di: New Journal of Chemistry, 2009, Vol.33(2), pp.366-375
  • Soggetti: Imaging
  • Tipo: Articolo
  • Identificativo: ISSN: 1144-0546 ; E-ISSN: 1369-9261 ; DOI: 10.1039/b816864d
  • Fonte: Royal Society of Chemistry

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