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Tetramer compound of manganese ions with mixed valence [Mn2IIMn2IV] and its spatial, electronic and magnetic studies.
1 , 2 , 3 , 3 , 1 , * 1
1  Principal Investigator at the Chemistry Centre, Benemérita Universidad Autónoma de Puebla.
2  Principal Investigator, Physics Institute, Benemérita Universidad Autónoma de Puebla
3  Principal Investigator at the Physics and Mathematics College, Instituto Politécnico Nacional.

Abstract:

In this work we report the synthesis, structural, electronic and magnetic characterization of [MnIV2MnII2(HL)2(H2L)2(H2O)4](NO3)2  1. This novel compound was obtained from (E)-2-((2-hydroxybenzylidene)amine)-2-(hydroximethyl-propane-1,3-diol, (H4L) and Mn(NO3)2. The UV-Vis and IR spectrophotometry showed the typical d-d transitions of MnIV in and octahedral geometry compounds 1 and vibrational transitions in 477 cm-1, which is assigned to the Mn-O group 2. The cM vs T gave J = 164 cm-1 3. The ESR (g = 11.03, 4.87, 1.78, and g = 3.23, 2.03) analysis of 1 showed the presence of MnII (s = 5/2) and MnIV (s = 3/2) ions within the molecule. The hyperfine interaction is observed in ESR spectrum which showed two species of Mn ions4. An x ray diffraction suitable monocristal of 1 was obtained and its structure was possible to describe as a tetramer of [MnIV MnII MnII MnIV] building a 2D stepped supramolecular structure with a step of [MnIV–O-O-MnII] and a second step with [MnII–O-O-MnIV]. The structural study informed us that each magnetic box of [MnIV-O-O-MnII] have a superexchange antiferromagnetic interaction by the dx2-y2-sp3 (with more contribution of p orbitals) orbitals; however, among the boxes or steps there is a super-exchange ferromagnetic interaction, by oxo bonds MnII-O-MnII.

  1. Ye T., Li S., Wu X., Xu M., Wei X., Wang K., Bao H., Wang J. and Chen J. J. Mater. Chem. C, 2013, 1, 4327–4333. Lever A. B. P. Inorganic Electronic Spectroscopy. 2a Edition. Elsevier, 1997.
  2. Czernuszewicz S. R., Su O. Y., Stern K. M., Macor A. K., Kim D., Groves T. J. and Spiro G. T. Am. Chem. Soc. 1988, 110, 4158-4165. Nakamoto K. Infrared and Raman Spectra of Inorganic and Coordination Compounds. 6a edition, John Wiley & Sons, 2009.
  3. Yoo J., Brechin E., Yamaguchi A., Nakano M., Huffman C. J., Maniero L. A., Brunel L. C., Awaga K., Ishimoto H., Christou G. y Hendrickson D. Chem. 2000, 39, 3615-3623. Milios J. C., Piligkos S., Bell R. A., Laye H. R., Teat J. S., Vicente R., McInnes E., Escuer A., Perlepes P. S. y Winpenny P. E. R. Inorganic Chemistry Communications. 2006, 9, 638–641.
  4. Ramírez R. D., Zamorano U. R., Pérez M. O. Solid State Communications. 2001, 118, 371-376.
Keywords: Intermolecular interactions; intramolecular interactions; coordination geometry
Comments on this paper
Alberto Girlando
Spectroscopic techniques
I wander how you can compare spectra obtained from solution (UvVis, nmr, esr) with the IR spectra which ahev been collected in KBr pellets (also using pressure, and embed the system in a polar matrix...)

Yasmi Reyes-Ortega
Reply to Dr. Alberto Girlando
Thank you for your comment and for reading our abstract. UV-Vis and NMR are experiments that we perform in solution because of the nature of the equipment, contrasting with the X-ray diffraction, IR and part of the ESR studies that were performed in solid. More that comparing the results, by using different state spectroscopies we aim to complement the characterization of compound 1. Using UV-Vis in solution and in solid state samples, we observed that the geometry around each Mn ion in solution is the same as in the solid state, only that the spectrum in solution is better and the transitions are better resolved too. Also, the ESR analysis supports what is observed in the X-ray spatial structure, since ESR is a spectroscopic technique that focuses in the local geometry of the metallic ion. Additionally, the dilution process in the ESR studies was performed to evaluate the behavior of the molecules when they are isolated, the magnetic interactions are weak and could reveal that the electron perceives its own nucleus by showing the hyperfine coupling in the spectrum. Based on this, we were able to correlate all spectroscopic studies in solid and solution samples and conclude our research.



 
 
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