The use of di-2-pyridyl ketone in manganese(II) benzoate chemistry: Two novel Mn-3(II) linkage isomers containing the ketone form of the ligand and a neutral Mn-4(II) cubane containing the ligand in its gem-diolate(-1) form

Constantinos C. Stoumpos, Ian A. Gass, Constantinos J. Milios, Elena Kefalloniti, Catherine P. Raptopoulou, Aris Terzis, Nikolia Lalloti, Euan K. Brechin, Spyros P. Perlepes

Research output: Contribution to journalArticlepeer-review

Abstract

The use of di-2-pyridyl ketone, (py)(2)CO, in manganese(II) benzoate chemistry has yielded two Mn-3(II) linkage isomers containing the ketone form of the ligand and a neutral Mn-4(II) cubane cluster containing the gem-diolate(-1) form of the ligand. The 3:2 Mn(O2CPh)(2)center dot 2H(2)O/(py)(2)CO reaction system in MeCN gives a mixture of the orange complex [Mn-3(O2CPh)(6){(py)(2)CO-kappa N-2,N'}(2)] (1) and the yellow compound [Mn-3(O2CPh)(6){(py)(2)CO-kappa N-2,O}(2)]center dot 2MeCN (2.2MeCN). The known compound [Mn6O2(O2CPh)(10)(MeCN)(4)] (3) appears as a by-product when the initial reaction solution, that leads to 1 and 2.2MeCN, is allowed to slowly evaporate in the air. The trinuclear molecules adopt a linear structure in both complexes, with one monoatornically bridging eta(1):eta(1):mu(2)and two syn,syn- eta(1):eta(1):mu(2) carboxylate groups spanning each pair of Mn-II ions. The terminal Mn-II ions are each capped by one chelating-N,N' (py)(2)CO ligand in 1 and by one chelating-N,O (py)(2)CO molecule in 2. The 1:1 reaction of Mn(O2CPh)(2)center dot 2H(2)O and (py)(2)CO in CH2Cl2 results in the isolation of [Mn-4(O2CPh)(4){(py)(2)C(OH)O}(4)](4). The tetranuclear molecule has a cubane topology with the Mn-II ions and the deprotonated oxygen atoms from the (py)(2)C(OH)O- ligands occupying alternate vertices. The IR data are discussed in terms of the nature of the bonding. The magnetic properties of 4 in the 300-5 K range have been modeled with two J values and reveal weak intramolecular antiferromagnetic interactions. The low temperature X-band EPR spectra of 1, 2 and 4 are also discussed. (C) 2007 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)196-202
Number of pages7
JournalInorganic chemistry communications
Volume11
Issue number2
DOIs
Publication statusPublished - Feb 2008

Keywords

  • di-2-pyridyl ketone complexes
  • EPR spectra
  • magnetic properties
  • manganese(II) benzoate clusters
  • manganese(II) cubanes
  • SINGLE-MOLECULE MAGNETS
  • GEM-DIOL FORM
  • CRYSTAL-STRUCTURES
  • SCATTERING SPECTRA
  • ENERGY-LEVELS
  • COMPLEXES
  • CLUSTERS
  • MAGNETIZATION
  • CUBES
  • OCTANUCLEARITY

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