title: 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.
abstract: 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 atT[Formula: see text] = 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, and57Fe Mössbauer spectra.
authors.affiliation: Institute of Applied Synthetic Chemistry, Vienna University of Technology Getreidemarkt 9/163-AC, 1060 Vienna, Austria.
authors.forename: Danny
authors.initials: D
authors.lastname: Müller
authors.forename: Christian
authors.initials: C
authors.lastname: Knoll
authors.forename: Berthold
authors.initials: B
authors.lastname: Stöger
authors.forename: Werner
authors.initials: W
authors.lastname: Artner
authors.forename: Michael
authors.initials: M
authors.lastname: Reissner
authors.forename: Peter
authors.initials: P
authors.lastname: Weinberger
keywords: Iron; Ligand design; Magnetic properties; N ligands; Spin crossover