Thermal-induced changes in molecular magnets based on Prussian blue analogues

R. Martínez-Garcia, M. Knobel, E. Reguera

Research output: Contribution to journalArticle

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Abstract

The thermal-induced changes in molecular magnets based on Prussian blue analogues, M 3 [Fe(CN) 6 ] 2 ·xH 2 O (M = Mn, Co, Ni, Cu, Zn, and Cd), were studied from infrared, X-ray diffraction, thermo-gravimetric, Mössbauer, and magnetic data. Upon being heated, these materials loose the crystalline water that enhances the interaction between the metal centers, as has been detected from Mössbauer spectroscopy data. At higher temperatures, a progressive decomposition process takes place, liberating CN - groups, which reduces the iron atom from Fe(III) to Fe(II) to form hexacyanoferrates(II). The exception corresponds to the cobalt compound that undergoes an inner charge transfer to form Co(III) hexacyanoferrate(II). In the case of zinc ferricyanide, the thermal decomposition is preceded by a structural transformation, from cubic to hexagonal. For M = Co, Ni, Cu, and Zn the intermediate reaction product corresponds to a solid solution of M(II) ferricyanide and ferrocyanide. For M = Mn and Cd the formation of a solid solution on heating was not detected. The crystal frameworks of the initial M(II) ferricyanide and of the formed M(II) ferrocyanide are quite different. In annealed Mn(II) ferricyanide samples, an increasing anti-ferromagnetic contribution on heating, which dominates on the initial ferrimagnetic order, was observed. Such a contribution was attributed to neighboring Mn(II) ions linked by aquo bridges. In the anhydrous annealed sample such interaction disappears. This effect was also studied in pure Mn(II) ferrocyanide. The occurrence of linkage isomerism and also the formation of Ni(III), Cu(III), and Zn(III) hexacyanoferrates(II) were discarded from the obtained experimental evidence. © 2006 American Chemical Society.
Original languageAmerican English
Pages (from-to)7296-7303
Number of pages8
JournalJournal of Physical Chemistry B
DOIs
StatePublished - 13 Apr 2006
Externally publishedYes

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Magnets
Solid solutions
solid solutions
magnets
Cobalt compounds
cobalt compounds
analogs
Heating
heating
Reaction products
linkages
reaction products
thermal decomposition
Charge transfer
Pyrolysis
Zinc
zinc
charge transfer
interactions
Spectroscopy

Cite this

@article{0032c4550c514ee49b25377356fa04c6,
title = "Thermal-induced changes in molecular magnets based on Prussian blue analogues",
abstract = "The thermal-induced changes in molecular magnets based on Prussian blue analogues, M 3 [Fe(CN) 6 ] 2 ·xH 2 O (M = Mn, Co, Ni, Cu, Zn, and Cd), were studied from infrared, X-ray diffraction, thermo-gravimetric, M{\"o}ssbauer, and magnetic data. Upon being heated, these materials loose the crystalline water that enhances the interaction between the metal centers, as has been detected from M{\"o}ssbauer spectroscopy data. At higher temperatures, a progressive decomposition process takes place, liberating CN - groups, which reduces the iron atom from Fe(III) to Fe(II) to form hexacyanoferrates(II). The exception corresponds to the cobalt compound that undergoes an inner charge transfer to form Co(III) hexacyanoferrate(II). In the case of zinc ferricyanide, the thermal decomposition is preceded by a structural transformation, from cubic to hexagonal. For M = Co, Ni, Cu, and Zn the intermediate reaction product corresponds to a solid solution of M(II) ferricyanide and ferrocyanide. For M = Mn and Cd the formation of a solid solution on heating was not detected. The crystal frameworks of the initial M(II) ferricyanide and of the formed M(II) ferrocyanide are quite different. In annealed Mn(II) ferricyanide samples, an increasing anti-ferromagnetic contribution on heating, which dominates on the initial ferrimagnetic order, was observed. Such a contribution was attributed to neighboring Mn(II) ions linked by aquo bridges. In the anhydrous annealed sample such interaction disappears. This effect was also studied in pure Mn(II) ferrocyanide. The occurrence of linkage isomerism and also the formation of Ni(III), Cu(III), and Zn(III) hexacyanoferrates(II) were discarded from the obtained experimental evidence. {\circledC} 2006 American Chemical Society.",
author = "R. Mart{\'i}nez-Garcia and M. Knobel and E. Reguera",
year = "2006",
month = "4",
day = "13",
doi = "10.1021/jp0555551",
language = "American English",
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journal = "Journal of Physical Chemistry B",
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}

Thermal-induced changes in molecular magnets based on Prussian blue analogues. / Martínez-Garcia, R.; Knobel, M.; Reguera, E.

In: Journal of Physical Chemistry B, 13.04.2006, p. 7296-7303.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Thermal-induced changes in molecular magnets based on Prussian blue analogues

AU - Martínez-Garcia, R.

AU - Knobel, M.

AU - Reguera, E.

PY - 2006/4/13

Y1 - 2006/4/13

N2 - The thermal-induced changes in molecular magnets based on Prussian blue analogues, M 3 [Fe(CN) 6 ] 2 ·xH 2 O (M = Mn, Co, Ni, Cu, Zn, and Cd), were studied from infrared, X-ray diffraction, thermo-gravimetric, Mössbauer, and magnetic data. Upon being heated, these materials loose the crystalline water that enhances the interaction between the metal centers, as has been detected from Mössbauer spectroscopy data. At higher temperatures, a progressive decomposition process takes place, liberating CN - groups, which reduces the iron atom from Fe(III) to Fe(II) to form hexacyanoferrates(II). The exception corresponds to the cobalt compound that undergoes an inner charge transfer to form Co(III) hexacyanoferrate(II). In the case of zinc ferricyanide, the thermal decomposition is preceded by a structural transformation, from cubic to hexagonal. For M = Co, Ni, Cu, and Zn the intermediate reaction product corresponds to a solid solution of M(II) ferricyanide and ferrocyanide. For M = Mn and Cd the formation of a solid solution on heating was not detected. The crystal frameworks of the initial M(II) ferricyanide and of the formed M(II) ferrocyanide are quite different. In annealed Mn(II) ferricyanide samples, an increasing anti-ferromagnetic contribution on heating, which dominates on the initial ferrimagnetic order, was observed. Such a contribution was attributed to neighboring Mn(II) ions linked by aquo bridges. In the anhydrous annealed sample such interaction disappears. This effect was also studied in pure Mn(II) ferrocyanide. The occurrence of linkage isomerism and also the formation of Ni(III), Cu(III), and Zn(III) hexacyanoferrates(II) were discarded from the obtained experimental evidence. © 2006 American Chemical Society.

AB - The thermal-induced changes in molecular magnets based on Prussian blue analogues, M 3 [Fe(CN) 6 ] 2 ·xH 2 O (M = Mn, Co, Ni, Cu, Zn, and Cd), were studied from infrared, X-ray diffraction, thermo-gravimetric, Mössbauer, and magnetic data. Upon being heated, these materials loose the crystalline water that enhances the interaction between the metal centers, as has been detected from Mössbauer spectroscopy data. At higher temperatures, a progressive decomposition process takes place, liberating CN - groups, which reduces the iron atom from Fe(III) to Fe(II) to form hexacyanoferrates(II). The exception corresponds to the cobalt compound that undergoes an inner charge transfer to form Co(III) hexacyanoferrate(II). In the case of zinc ferricyanide, the thermal decomposition is preceded by a structural transformation, from cubic to hexagonal. For M = Co, Ni, Cu, and Zn the intermediate reaction product corresponds to a solid solution of M(II) ferricyanide and ferrocyanide. For M = Mn and Cd the formation of a solid solution on heating was not detected. The crystal frameworks of the initial M(II) ferricyanide and of the formed M(II) ferrocyanide are quite different. In annealed Mn(II) ferricyanide samples, an increasing anti-ferromagnetic contribution on heating, which dominates on the initial ferrimagnetic order, was observed. Such a contribution was attributed to neighboring Mn(II) ions linked by aquo bridges. In the anhydrous annealed sample such interaction disappears. This effect was also studied in pure Mn(II) ferrocyanide. The occurrence of linkage isomerism and also the formation of Ni(III), Cu(III), and Zn(III) hexacyanoferrates(II) were discarded from the obtained experimental evidence. © 2006 American Chemical Society.

U2 - 10.1021/jp0555551

DO - 10.1021/jp0555551

M3 - Article

C2 - 16599501

SP - 7296

EP - 7303

JO - Journal of Physical Chemistry B

JF - Journal of Physical Chemistry B

SN - 1520-6106

ER -