Synthesis and X-ray structure of the MnIICl2 and MnIIIF2 complexes of N,N'-dimethyl-2,11-diaza[3,3](2,6)pyridinophane. High-field electron paramagnetic resonance and density functional theory studies of the MnIII complex. Evidence for a low-lying spin triplet state

Inorg Chem. 2005 Oct 3;44(20):6959-66. doi: 10.1021/ic048302f.

Abstract

Two manganese complexes, (py2(NMe)2)MnIICl2 (1) and [(py2(NMe)2)MnIIIF2]+ (2), are here described with the macrocyclic ligand py2(NMe)2 (py2(NMe)2 = N,N'-dimethyl-2,11-diaza[3,3](2,6)pyridinophane). For both, the crystal structure is reported. The UV-visible spectrum of 2 exhibits a very broad near-infrared (NIR) band corresponding to the transition between the two e(g)-type orbitals split by the Jahn-Teller effect. A negative D value of ca. -4 cm(-1) was estimated by high-field and high-frequency electron paramagnetic resonance (HF-EPR) spectroscopy, which was consistent with symmetry considerations. Density functional theory (DFT) calculations on 2 support the 5B1 electronic ground state predicted from the X-ray structure. Moreover, to explain the large value of the D parameter, a spin triplet first excited spin state was postulated to occur at low energy. This was confirmed by the DFT calculations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aza Compounds / chemical synthesis
  • Aza Compounds / chemistry*
  • Chlorides / chemistry*
  • Electron Spin Resonance Spectroscopy / methods
  • Manganese Compounds / chemistry*
  • Manganese*
  • Models, Molecular
  • Pyridines / chemical synthesis
  • Pyridines / chemistry*
  • X-Ray Diffraction

Substances

  • Aza Compounds
  • Chlorides
  • Manganese Compounds
  • N,N'-dimethyl-2,11-diaza(3,3)(2,6)pyridinophane
  • Pyridines
  • Manganese
  • manganese chloride