Synthesis and investigation of mono- and multinuclear molecular coordination compounds with physical and chemical induced electronic multistability

• Antragsteller: Professor Dr. Franz Renz
• Fachliche Zuordnung: Anorganische Molekülchemie - Synthese, Charakterisierung
• Förderung: Förderung von 2002 bis 2008
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5369704

• Erstellungsjahr: 2011

Zusammenfassung der Projektergebnisse

Serveral series of compound have been prepared and investigated. Such as the reaction of 12 different iron(III)-complexes with five different octa- (Mo, W) and hexacyanides (Co, Ru, Fe) yield 40 different multinuclear complexes. Among them are 14 nonanuclear compounds, consisting of seven Mo (21-27) and seven W (28-34). Followed by additional 26 heptanuclear compounds, consisting of eleven Co (35- 41)&(53-56), eleven Ru (42-48)&(57-60) and four Fe (49-52). With the choice of the ligand coordinating the iron(III) precursor we investigate the different electronic and sterical influences on the magnetic and electronic behaviour through variation of the carbon chain length, substitution in N-Position and substitution on the aromatic rings. Infrared and mass spectroscopy indicate the formation of nona- and heptanuclear complexes. Elemental analysis didn’t appear to be too precise due to formation of metal carbides and other non-volatile compounds. Mössbauer spectroscopy identified at least twelve products performing thermal switching between ground state and excited state, among them are (23,24,27,29,30,36,37,45,53,54,57,58). Magnetic susceptibility measurements perfomed on (23,29,30,36,37,45) in the temperature range from 5 K to 300 K confirmed a corresponding change in the effective magnetic moment. The large number of high-spin centers in the molecule bears a strong magnetic moment and a total spin for the complex at high temperature. The experimental values estimated at room temperature are about 8/2 to 17/2. For the nonanuclear complexes a Smax of 40/2 is the upper limit. Mössbauer spectra at 20 K under light irradiation revealed a change of the spin state. This is unexpected for pentadentate Fe(III)-complexes and may be based on an light induced electron transfer between central metal and complex periphery. Highlights: Several new effects have been discovered: (1) thermal sequential and light induced concerted switching in multinuclear starshaped compounds, (2) the excited state-life-time prolongation by around 15 orders of magnitude SF-LIESST effect, (3) the light switching at room temperature LiPTH effect, (4) first dodecanuclear switching compound, (5) first heptanuclear X-ray of switching compound, (6) surface linked star-shaped compounds.

Projektbezogene Publikationen (Auswahl)

• Molecular sensors for moisture detection by Mössbauer spectroscopy. Hyperfine Interactions, Vol. 139. 2002, Issue 1, pp 699–704.
  F. Renz, P.A. de Souza jun., G. Klingelhöfer, H.A. Goodwin
  
• Spin crossover in iron(II) tris(2-(2'-pyridyl)benzimidazole) complex monitored by variable temperature methods: synchrotron powder diffraction, DSC, IR spectra, Mössbauer spectra, and magnetic susceptibility. Chemical Physics, Vol. 293. 2003, Issue 3, pp. 375–395.
  R. Boca, M. Boca, H. Ehrenberg, H. Fuess, W. Linert, F. Renz and I. Svoboda
  
• Mössbauer investigation of "Bounce Rock" at Meridiani Planum on Mars - Indications for the first shergottite on Mars. Meteoritics & Planetary Science, Vol. 39.2004, Issue S8, pp. A91.
  D.S. Rodionov, C. Schröder, G. Klingelhöfer, R.V. Morris, B. Bernhardt, P.A. de Souza, A. Yen, F. Renz, T. Wdowiak, S.W. Squyres and the Athena Science Team
  
• Recent Advances of Spin Crossover Research. In: Optical Spectra and Chemical Bonding in Transition Metal Complexes. Structure and Bonding, Vol. 107.2004, pp. 27-75.
  P. Gütlich, P. van Koningsbruggen, F. Renz
  
• Metallosupramolecular coordination polyelectrolytes investigated by Mössbauer spectroscopy. In „ICAME2005“, Eds. P.-E. Lippens, J.-C. Jumas and J.-M.R. Genin. Hyperfine Interactions, Vol. 166. 2005, Issue 1, pp 465–468.
  A. Lindner, M. Mentzel, F. Renz, D.G. Kurth, A. Thünemann
  
• Unprecedented Multiple Electronic Spin Transition in Hepta- and Nonanuclear Complex Compounds Observed by Mössbauer Spectroscopy. Polyhedron, Vol. 24. 2005, Issues 16–17, pp. 2849–2851.
  Franz Renz, Patrick Kerep
  
• Induktion langlebiger angeregter Spinzustände durch harte Röntgenstrahlung. Angewandte Chemie, Vol. 119. 2007, Issue 28, pp. 5400–5403.
  Gyorgy Vanko, Franz Renz, Gabor Molnar, Thomas Neisius, Szilvia Karpatik
  
• Unprecedented multistability in dodecanuclear complex compound obsereved by Mössbauer spectroscopy. Polyhedron, Vol. 26. 2007, Issues 9–11, pp. 2325–2329.
  F. Renz, D. Hill, M. Klein, J. Hefner
  
• Chemical tuning by 5-Me, and N-Me-substitution in [N-R/5-Me/Fe/X] complexes effects multistability investigated by Mössbauer spectroscopy. In “ICAME2007”, ed. N.S. Gajbhiye and S.K. Date, Springer-Verlag, 2008, pp. 673-679.
  F. Renz, V. Martinez, M. Klein, M. Schott, T. Hoffmann, M. Blumers, I. Fleischer, G. Klingelhöfer, R. Boca, M. Menzel
  
• Investigation of Mo- and W- stannylidyne complexes by Mössbauer Spectroscopy. In: ICAME 2007, Proceedings of the 29th International Conference on the Applications of the Mössbauer Effect (ICAME 2007) held in Kanpur, India, 14-19 October 2007,ed. N.S. Gajbhiye and S.K. Date, Springer-Verlag, 2008, pp. 809-812.
  H. Rohde, M. Menzel, F. Renz, A.C. Filippou
  
• High-spin Schiff-base dinuclear iron(III) complexes bridged by N-oxide ligands. Inorganica Chimica Acta, Vol. 362. 2009, Issue 13, pp. 4754–4759.
  I. Nemec; R. Boca; M. Gembicky; L. Dlhan; R. Herchel; F. Renz
  
• Interplay between spin crossover and exchange interaction in iron(III) complexes. Pure and Applied Chemistry - The Scientific Journal of IUPAC, Band 81. 2009, Heft 8, S.1357–1383.
  Roman Boča, Ivan Nemec, Ivan Šalitroš, Ján Pavlik, Radovan Herchel, Franz Renz
  
• Unconventional Spin Crossover in Dinuclear and Trinuclear Iron(III) Complexes with Cyanido and Metallacyanido Bridges. European Journal of Inorganic Chemistry, Vol. 2009, Issue 21, pp. 3141–3154.
  I. Salitros; R. Boca; L. Dlhan; M. Gembicky; J. Kozisek; J. Linares; J. Moncol; I. Nemec; L. Perasinova; F. Renz; I. Svoboda; H. Fuess
  
• Competing redox reactions in Fe-containing AlO(OH) and Al2O3 matrices: A combined investigation by Mössbauer, ESR spectroscopy and thermal analysis. Journal of Physics: Conference Series, Vol. 217.2010, Number 1: 012028.
  R. Stößer, M. Menzel, M. Feist, M. Nofz, F. Renz
  
• Molecular switching in iron complexes bridged via tin- cyanides observed by Mössbauer and ESR spectroscopy. Journal of Physics: Conference Series, Vol. 217. 2010, Number 1: 012027.
  Stefan Jung, Franz Renz, Michael Klein, Michael Menzel, Roman Boča, R Stößer,
  
• Spin crossover in a heptanuclear mixed-valence iron Complex. Dalton Transactions, Vol. 39. 2010, Issue 9, pp. 2198-2200.
  Roman Boča, Ivan Šalitroš, Jozef Kožíšek, Jorge Linares, Ján MoncoĬ, Franz Renz