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D. Müller, C. Knoll, B. Stöger, W. Artner, M. Reissner, P. Weinberger:
"A Modified Synthetic Pathway for the Synthesis of so far Inaccessible N1-Functionalized Tetrazole Ligands - Synthesis and Characterization of the 1D Chain-Type Spin Crossover Compound [Fe(3ditz)3](BF4)2";
European Journal of Inorganic Chemistry (invited), cluster issue (2013), 984 - 991.

A modified phase-transfer-catalyst-assisted synthetic pathway was developed that widens the pool of accessible 1-substituted tetrazoles, which are possible ligands for iron(II) spin-crossover compounds. Within the family of α,ω-bis(tetrazol-1-yl)alkanes, a series of ligands and their respective iron(II) spin-crossover compounds were synthesized and structurally and spectroscopically characterized in the past. The classical route to prepare these ligands is based on the respective amino-precursors. Hence the pool of accessible compounds is limited by the commercial or synthetical availability of α,ω-diaminoalkanes. Furthermore, the concomitant
transformation to the tetrazole moieties turns out to be easier
for diamino-alkanes with an even number of carbon atoms than for those with an odd number. In line with this observation, the shortest odd-numbered homologues such as 1,1-bis-(tetrazol-1-yl)methane (1ditz) and 1,3-bis(tetrazol-1-yl)propane (3ditz) were inaccessible so far. In this paper, we report the successful preparation and characterisation of the classically inaccessible 1,3-bis(tetrazol-1-yl)propane (3ditz) and of its spin-crossover complex [Fe(3ditz)3](BF4)2, which features an abrupt and almost complete spin transition at T½ = 159 K. The single-crystal X-ray structure of the low-spin and the high-spin species is presented. The magnetic data are supported
by variable-temperature IR, UV/Vis/NIR, and 57Fe Mössbauer spectra.

Ligand design / N ligands / Spin crossover / Magnetic properties / Iron

http://dx.doi.org/10.1002/ejic.201201062

http://publik.tuwien.ac.at/files/PubDat_217138.pdf