[Zurück]

J. Schweifer, P. Weinberger, K. Mereiter, M. Boca, C. Reichl, G. Wiesinger, G. Hilscher, P. Van Koningsbruggen, H. Kooijman, M. Grunert, W. Linert:
"Catena[µ-Tris(1,,2-bis(tetrazol-1-yl)ethane-N1,N1´)iron(II)]Bis(tetrafluoroborate): Synthesis, Structure, Spectroscopic and Magnetic Characterisation of a Chain-type Coordination Polymer Spin-Crossover Compound";
Inorganica Chimica Acta, 339 (2002), S. 297 - 306.

catena-[m-Tris(1,2-bis(tetrazol-1-yl)ethane-N4,N4?)iron(II)]
bis(tetrafluoroborate): synthesis, structure, spectroscopic and
magnetic characterization of a chain-type coordination polymer
spin-crossover compound

Johannes Schweifer a, Peter Weinberger a, Kurt Mereiter b, Miro Boca c,
Christoph Reichl d, Gu¨nter Wiesinger d, Gerfried Hilscher d, Petra J. van Koningsbruggen e, Huub Kooijman f, Matthias Grunert a, Wolfgang Linert a,*

a Institute for Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163, A-1060 Vienna, Austria
b Institute for Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, A-1060 Vienna, Austria
c Institute for Inorganic Chemistry, Slovak Technical University, Radlinskeho 9, SK-81237 Bratislava, Slovakia
d Institute for Experimental Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10/131, A-1040 Vienna, Austria
e Institute for Inorganic and Analytical Chemistry, Johannes-Gutenberg University, Staudingerweg 9, D-55099 Mainz, Germany
f Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands

Received 12 November 2001; accepted 22 March 2002

Abstract
In analogy to a common synthesis of 1-substituted 5-H tetrazoles (Tetrahedron Lett. 36 (1995)1759; Beloruss. Gos. Univ., Minsk,
USSR. Khim. Geterotsikl. Soedin. 11 (1985) 1521; Beloruss. Gos. Univ., Minsk, USSR. Khim. Geterotsikl. Soedin. 1 (1991) 66;
BGU, Belarus. Vestsi Akad. Navuk Belarusi, Ser. Khim. Navuk 1 (1992) 73), the new bidentate ligand 1,2-bis(tetrazol-1-yl)ethane [endi] was synthesized and characterized by X-ray diffraction, NMR, IR and UV /Vis spectroscopy. By using iron(II) tetrafluoroborate hexahydrate the complexation with this ligand yields a 1-dimensional linear coordination polymer similar to the recently published chain compound (Inorg. Chem. 39 (2000) 1891) exhibiting a thermally induced spin-crossover phenomenon.
Similar to the 1,2-bis(tetrazol-1-yl)propane-bridged compound, our 1,2-bis(tetrazol-1-yl)ethane-bridged compound shows a gradual
spin transition, but the spin-crossover temperature T1/2:/140 K is found to be 10 K above the other T1/2. The T1/2 was determined
by temperature-dependent 57Fe-Mo¨ssbauer, far FT-IR and UV /Vis spectroscopy as well as by temperature-dependent magnetic
susceptibility measurements. Single crystals of the complex were grown in situ from a solution of the ligand and iron(II) tetrafluoroborate. The X-ray structure determinations of both the high spin as well as the low spin state of the compound revealed a solid state structure, which is comparable to that of catena -[Fe(1,2-bis(tetrazole-1-yl)propane)3](ClO4)2 (Inorg. Chem. 39 (2000)
1891; 2nd TMR-TOSS Meeting, 4th Spin Crossover Family Meeting, Lufthansa Training Center, Seeheim/Germany, April 30 /May
2, 1999). Both the 1,2-bis(tetrazol-1-yl)propane-bridged and our compound do not show a thermal hysteresis effect (J. Am. Chem.
Soc. 115 (1993) 9810; Inorg. Chim. Acta 37 (1979) 169; Chem. Phys. Lett. 93 (1982) 567). The synthesis of the complex described in
the experimental section yielded a fine powdered product being poorly soluble in most common solvents. The single crystal measurements were done with crystals obtained by various diffusion methods. Most of them yielded either thin needles or small hexagonal prism crystals depending on the specific conditions.
# 2002 Elsevier Science B.V. All rights reserved.

Keywords: Mo¨ssbauer; SQUID; X-ray diffraction; Far FT-IR; Spin transition; Iron(II) coordination polymer