5-Aminotetrazole induces spin crossover in iron(III) pentadentate Schiff base complexes: experimental and theoretical investigations

A series of novel mononuclear iron(III) complexes [Fe(saldpt)(atz)] (1) and [Fe(Rsalpet)(atz)] (2a-d) involving 5-aminotetrazole (Hatz) and pentadentate Schiff base ligands (H2saldpt = N,N'-bis(2-hydroxybenzyliden)-1,7-diamino-4-azaheptane, H2salpet = N,N'-bis(2-hydroxybenzyliden)-1,6-diam...

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Bibliographic Details
Published in:Dalton transactions : an international journal of inorganic chemistry 2013-12, Vol.42 (46), p.16279-16288
Main Authors: Herchel, Radovan, Trávníček, Zdeněk
Format: Article
Language:English
Subjects:
Conductors (devices)
Critical temperature
Crossovers
Entropy
Magnetic properties
Mathematical models
Mossbauer spectroscopy
Schiff bases
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Summary:A series of novel mononuclear iron(III) complexes [Fe(saldpt)(atz)] (1) and [Fe(Rsalpet)(atz)] (2a-d) involving 5-aminotetrazole (Hatz) and pentadentate Schiff base ligands (H2saldpt = N,N'-bis(2-hydroxybenzyliden)-1,7-diamino-4-azaheptane, H2salpet = N,N'-bis(2-hydroxybenzyliden)-1,6-diamino-3-azahexane, H25Cl-salpet = N,N'-bis(5-chloro-2-hydroxybenzylidene)-1,6-diamino-3-azahexane, H25Br-salpet = N,N'-bis(5-bromo-2-hydroxybenzylidene)-1,6-diamino-3-azahexane and H23,5Br-salpet = N,N'-bis(3,5-dibromo-2-hydroxybenzylidene)-1,6-diamino-3-azahexane) was prepared and characterized by elemental analysis, FTIR spectroscopy, mass spectrometry, single crystal X-ray analysis, magnetic measurements and (57)Fe Mössbauer spectroscopy. In contrast to the high-spin magnetic properties of [Fe(saldpt)(atz)] (1), the complexes [Fe(Rsalpet)(atz)] (2a-d) undergo spin crossover with critical temperatures above 416 K. Furthermore, DFT calculations with the B3LYP functional were employed to investigate the effect of the conductor-like screening model (COSMO) and van der Waals corrections (VDW) as well as relativistic effects with the scalar relativistic second-order Douglas-Kroll-Hess Hamiltonian (DKH2) on low-spin and high-spin molecular geometries and thus on spin crossover parameters (enthalpy, entropy and critical temperature).
ISSN:1477-9226
1477-9234
DOI:10.1039/c3dt52301b