Synthesis and anomalous magnetic properties of heterometal dinuclear Fe(II)–Cr(III) complex bridged by 3,5-bis(pyridin-2-yl)-pyrazolate

• Published in: Inorganica Chimica Acta Vol. 357; no. 9; pp. 2437 - 2440
• Main Authors: Kawamura, Yasuaki, Tsukahara, Yasunori, Nasu, Saburo, Morimoto, Syotaro, Fuyuhiro, Akira, Kaizaki, Sumio
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-07-2004
• Subjects: Chromium(III); Dinuclear complex; Iron(II); Magnetic interaction; Spin-crossover; Dinuclear complex; Chromium(III); Magnetic interaction; Spin-crossover; Iron(II)
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2004.03.024

Newly synthesized [(nta)Cr(μ-bpypz)Fe(dpea)]BF
4
·
4CH
3OH, where bpypz=3,5-bis(pyridin-2-yl)-pyazolate, nta=nitrilotriacetate and dpea=(2-aminoethyl)-bis(2-pyridylmethyl)amine, was characterized to be the dinuclear structure by ESI-MS and
2H NMR spectra, for which the anomalous magnetic behavior shows antiferromagnetic interaction and/or spin-crossover; suggesting complementarity between spin-crossover and magnetic interaction.
A Cr(III)–Fe(II) dinuclear complex [(nta)Cr(μ-bpypz)Fe(dpea)]BF
4, where bpypz=3,5-bis(pyridin-2-yl)-pyazolate, nta=nitrilotriacetate and dpea=(2-aminoethyl)-bis(2-pyridylmethyl)amine, has been synthesized and structurally characterized by ESI-MS and
2H NMR spectra. The proposed structure is mostly more planar in the bridging moiety as compared to that of the previously reported [(nta)Cr(μ-bpypz)Fe(picen)]BF
4(
N,
N
′-bis-(2-pyridylmethyl)ethylenediamine(picen)). The dpea complex is found to be a high spin state, but to exhibit no spin-crossover by magnetic susceptibility and Mössbauer spectra measurements; showing a large antiferromagnetic interaction, which could make the spin transition temperature lower and/or destroy spin-crossover, suggesting complementarity between spin-crossover and magnetic interaction.