Employment of methyl 2-pyridyl ketone oxime in manganese non-carboxylate chemistry: MnII2MnIV and MnII2MnIII6 complexes

Constantinos C. Stoumpos, Theocharis C. Stamatatos, Harikleia Sartzi, Olivier Roubeau, Anastasios J. Tasiopoulos, Vassilios Nastopoulos, Simon J. Teat, George Christou*, Spyros P. Perlepes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

The employment of the anion of methyl 2-pyridyl ketone oxime (mpko-) as a tridentate chelating/bridging ligand in manganese chemistry is described. The inorganic anion (Br-, ClO4-) used in the reaction affects the identity of the product. The reaction of MnBr2 and one equivalent of mpkoH in the presence of a base affords [Mn3(OMe)2(mpko)4Br2] (3), which is mixed-valence (2MnII, MnIV). The central MnIV atom in each of the two, crystallographically independent, centrosymmetric molecules is coordinated by four oximate oxygen atoms belonging to the η111:μ mpko- ligands, and two η1:μ MeO- groups, while six coordination at each terminal MnII atom is completed by four nitrogen atoms belonging to the ‘chelating’ part of two mpko- ligands, and one Br- ion. The MnII atoms have trigonal prismatic coordination geometry. The reaction of Mn(ClO4)2·6H2O, mpkoH and OH- (1:2:1) in MeOH gives [Mn8O4(OMe)(mpko)9(mpkoH)](ClO4)4 (4), which is also mixed-valence (2MnII, 6MnIII) and possesses the novel [Mn83-O)4(μ-OMe)(μ-OR′)2]11+ core. The latter possesses a U-shaped sequence of four fused (MnIIMnIII23-O))6+ triangular units, with a MnIII-MnIII edge being shared between the central triangles. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on complexes 3 and 4. The dc susceptibility data for 3 in the 5.0–300 K range have been fit to a model with two J values, revealing weak ferromagnetic MnII⋯MnIV (J = +3.4 cm−1) and MnII⋯MnII (J′ = +0.3 cm−1) exchange interactions. Fitting of the magnetization vs. H/T data by matrix diagonalization and including only axial anisotropy (ZFS, D) gave ground state spin (S) and D values of S = 13/2, D = +0.17 cm−1 for 3 and S = 3, D = −0.09 cm−1 for 4. The combined work demonstrates the usefulness of mpko- in the preparation of interesting Mn clusters, without requiring the co-presence of carboxylate ligands.

Original languageEnglish (US)
Pages (from-to)1004-1015
Number of pages12
JournalJournal of the Chemical Society. Dalton Transactions
Issue number6
DOIs
StatePublished - Jan 28 2009

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Employment of methyl 2-pyridyl ketone oxime in manganese non-carboxylate chemistry: Mn<sup>II</sup><sub>2</sub>Mn<sup>IV</sup> and Mn<sup>II</sup><sub>2</sub>Mn<sup>III</sup><sub>6</sub> complexes'. Together they form a unique fingerprint.

Cite this