TY - JOUR

T1 - Mixed-Valence Heptanuclear Iron Complexes with Ferromagnetic Interaction

AU - Šalitroš, Ivan

AU - Boča, Roman

AU - Herchel, Radovan

AU - Moncol, Ján

AU - Nemec, Ivan

AU - Ruben, Mario

AU - Renz, Franz

PY - 2012/12/3

Y1 - 2012/12/3

N2 - Three new Prussian blue analogues, heptanuclear mixed-valence iron complexes of the type [FeII(CN)6{FeIII(1 -2H)}6]Cl2·nH2O, were synthesized and structurally and spectrally characterized, and their magnetic properties were investigated (1-2H corresponds to doubly deprotoned Schiff-base pentadentate ligands 1a, N,N-bis(2-hydroxybenzylidene)-1,5-diamino- 3-azapentane, 1b, N,N-bis(3-ethoxy-2-hydroxybenzylidene)-1,7-diamino-4- azaheptane, or 1c, N,N′-bis(3-methoxy-2-hydroxybenzylidene)-1,6-diamino-3- azahexane). These compounds were formed by assembling the [Fe(CN) 6]4- building block with mononuclear complexes of the [Fe(1-2H)Cl] type. X-ray structure analysis revealed that the complexes adopt a star-like architecture: the Fe(II) ion lies at the very center, and on its octahedral nodes the Fe(III) sites are coordinated in the FeII-C ≡ N-FeIII manner. The Schiff-base pentadentate ligand moiety 1-2H coordinates a single Fe(III) center in two complexes 3b and 3c. Ligands 1a-2H in the complex cation of 3a adopt an unusual coordination mode: three donor atoms of the same ligand (one O and two N) coordinate one Fe(III), whereas the remaining N′ and O′ donor atoms coordinate the neighboring Fe(III) center creating the {Fe(ON 2)(N′O′)N″} chromophore involving two 1a -2H ligand moieties. Moreover, three Fe(III) centers are interconnected with three 1a-2H ligands in such a manner that two {FeIII3(1a-2H)3} units form two intramolecular rings. Magnetic investigation of the heptanuclear complexes revealed the high-spin state of all six Fe(III) coordination sites (s = 5/2), while the very central Fe(II) site is in the low-spin state (s = 0). At low temperature, the ferromagnetic exchange interactions stay evident for all three complexes. Mössbauer spectra of compounds 3a and 3b revealed a presence of two different doublets for both compounds: the major doublet is related to six Fe(III) high-spin coordination sites and the minor doublet refers to the low-spin very central Fe(II).

AB - Three new Prussian blue analogues, heptanuclear mixed-valence iron complexes of the type [FeII(CN)6{FeIII(1 -2H)}6]Cl2·nH2O, were synthesized and structurally and spectrally characterized, and their magnetic properties were investigated (1-2H corresponds to doubly deprotoned Schiff-base pentadentate ligands 1a, N,N-bis(2-hydroxybenzylidene)-1,5-diamino- 3-azapentane, 1b, N,N-bis(3-ethoxy-2-hydroxybenzylidene)-1,7-diamino-4- azaheptane, or 1c, N,N′-bis(3-methoxy-2-hydroxybenzylidene)-1,6-diamino-3- azahexane). These compounds were formed by assembling the [Fe(CN) 6]4- building block with mononuclear complexes of the [Fe(1-2H)Cl] type. X-ray structure analysis revealed that the complexes adopt a star-like architecture: the Fe(II) ion lies at the very center, and on its octahedral nodes the Fe(III) sites are coordinated in the FeII-C ≡ N-FeIII manner. The Schiff-base pentadentate ligand moiety 1-2H coordinates a single Fe(III) center in two complexes 3b and 3c. Ligands 1a-2H in the complex cation of 3a adopt an unusual coordination mode: three donor atoms of the same ligand (one O and two N) coordinate one Fe(III), whereas the remaining N′ and O′ donor atoms coordinate the neighboring Fe(III) center creating the {Fe(ON 2)(N′O′)N″} chromophore involving two 1a -2H ligand moieties. Moreover, three Fe(III) centers are interconnected with three 1a-2H ligands in such a manner that two {FeIII3(1a-2H)3} units form two intramolecular rings. Magnetic investigation of the heptanuclear complexes revealed the high-spin state of all six Fe(III) coordination sites (s = 5/2), while the very central Fe(II) site is in the low-spin state (s = 0). At low temperature, the ferromagnetic exchange interactions stay evident for all three complexes. Mössbauer spectra of compounds 3a and 3b revealed a presence of two different doublets for both compounds: the major doublet is related to six Fe(III) high-spin coordination sites and the minor doublet refers to the low-spin very central Fe(II).

UR - http://www.scopus.com/inward/record.url?scp=84870544548&partnerID=8YFLogxK

U2 - 10.1021/ic3015833

DO - 10.1021/ic3015833

M3 - Article

C2 - 23145981

AN - SCOPUS:84870544548

VL - 51

SP - 12755

EP - 12767

JO - Inorganic chemistry

JF - Inorganic chemistry

SN - 0020-1669

IS - 23

ER -