Trinuclear CuII complexes containing peripheral ketonic oxygen bridges and a μ3-OH core: Syntheses, crystal structures, spectroscopic and magnetic properties

Mau Sinha Ray, Shouvik Chattopadhyay, Michael G.B. Drew, Albert Figuerola, Joan Ribas, Carmen Diaz*, Ashutosh Ghosh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

72 Scopus citations

Abstract

Four new trinuclear copper(II) complexes, [(CuL1) 33-OH)](ClO4)2·H 2O (1), [(CuL2)33-OH)](ClO 4)2 (2), [(CuL3)3-(μ3- OH)](ClO4)2·H2O (3), and [(CuL 4)33-OH)](ClO4) 2·H2O (4), where HL1 = 8-amino-4,7,7-trimethyl-5-azaoct-3-en-2-one, HL2 = 7-amino-4-methyl-5-azaoct-3-en-2-one, HL3 = 7-(ethylamino)-4-methyl- 5-azahept-3-en-2-one, and HL4 = 4-methyl-7-(methylamino)-5-azahept-3- en-2-one, have been derived from the four tridentate Schiff bases (HL 1, HL2, HL3, and HL4) and structurally characterized by X-ray crystallography. For all compounds, the cationic part is trinuclear with a Cu3OH core held by three carbonyl oxygen bridges between each pair of copper(II) atoms. The copper atoms are five-coordinate with a distorted square-pyramidal geometry; the equatorial plane consists of the bridging oxygen atom of the central OH group together with three atoms (N, N, O) from one ligand whereas an oxygen atom of a second ligand occupies the axial position. Magnetic measurements have been performed in the 2-300 K temperature range. The experimental data could be satisfactorily reproduced by using an isotropic exchange model, H = -J(S1S 2+S2S3+S1S3) yielding as best-fit parameters: J = -66.7 and g = 2.19 for 1, J = -36.6 and g = 2.20 for 2, J = -24.5 and g = 2.20 for 3, and J = -14.9 and g = 2.05 for 4. EPR spectra at low temperature show the existence of spin frustration in complexes 3 and 4, but it has not been possible to carry out calculations of the antisymmetric exchange parameter, G, from magnetic data. In frozen methanolic solution, at 4 K, hyperfine splitting in all complexes and spin frustration in complex 4 seem to be confirmed.

Original languageEnglish (US)
Pages (from-to)4562-4571
Number of pages10
JournalEuropean Journal of Inorganic Chemistry
Issue number22
DOIs
StatePublished - Nov 18 2005

Keywords

  • Copper trimers
  • Magnetic properties
  • Schiff bases
  • X-ray structures

ASJC Scopus subject areas

  • Inorganic Chemistry

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