Xanes of Manganese Coordination Complexes

Cartier, C.; Ménage, Stéphane; Girerd, Jean‐Jacques; Tuchagues, J. P.; Mabad, B.

doi:10.1051/jphyscol:19868117

Cited by 3 publications

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“…The intensity and energy of the K edge are typical of a Mn II ion in an octahedral surrounding, 64 and the features at the top of the edge clearly indicate a distorted compressed octahedral geometry. 65 On the other hand, the small shoulder observed at ca. 55 eV from the pre-edge, which may be assigned to bielectronic transitions, 66 is also typical of Mn II compounds.…”

Section: Resultsmentioning

confidence: 98%

“…In fact, the use of X-ray absorption techniques in this structural area is not new and they have been previously revelead as very useful tool in coordination chemistry. ,− The normalized XANES spectrum for complex 2 is shown in Figure a. The intensity and energy of the K edge are typical of a Mn II ion in an octahedral surrounding, and the features at the top of the edge clearly indicate a distorted compressed octahedral geometry . On the other hand, the small shoulder observed at ca .…”

Section: Resultsmentioning

confidence: 99%

“…The top of the edge is structured, and the shape suggests that the local environment of Mn II metal ion is octahedral elongated. 65 As in compound 2, four main peaks are observed in the experimental Fourier transform (Figure 5a): the first one corresponds to the first coordination sphere of the metal, the second and third peaks include mainly the remaining carbon atoms of the ligands, and the fourth one might be tentatively assigned to distances to the closest Mn as the greater contribution. Only the distance with the first Mn was tentatively assigned, since a second Mn may be located quite far from the absorber atom to have a considerable contribution in the spectrum.…”

Section: X-ray Absortion Studies Of [Mn(µ-4-clphcoo) 2 -(Bpy)] N ‚Nh ...mentioning

confidence: 97%

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Synthesis, Structural Characterization (X-ray and EXAFS), and Magnetic Properties of Polynuclear Manganese(II) Complexes with Chlorobenzoato Bridges

et al. 1998

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Three different types of polynuclear MnII complexes with carboxylate bridges were obtained from the reaction of Mn(RCOO)2 with 2,2‘-bipyridine (bpy). Dinuclear complexes [Mn2(μ-RCOO)2(bpy)4](ClO4)2 with R = 2-ClPh, 3-ClPh, 4-ClPh, Ph (1−4); trinuclear complexes [Mn3(μ-RCOO)6(bpy)2] with R = 2-ClPh, 3-ClPh (5, 6), [Mn3(μ-RCOO)6(2,2‘-Me2-bpy)2] with R = 2-ClPh, 3-ClPh, 4-ClPh (7−9), and 1D complexes [Mn(μ-RCOO)2(bpy)] n with R = 3-ClPh, 4-ClPh (10, 11). [Mn2(μ-PhCOO)2(bpy)4](ClO4)2 (4) and the [Mn(μ-3-ClPhCOO)2(bpy)] n ·nH2O (10) have been characterized by X-ray diffraction. Complex 4 crystallizes in the triclinic system, space group P1̄ with a = 9.1886(10) Å, b = 11.6135(9) Å, c = 13.595(2) Å, α = 66.225(13)°, β = 84.073(12)°, γ = 88.593(10)°, Z = 1. Complex 10 crystallizes in the monoclinic system, space group C2/c with a = 26.376(5) Å, b = 12.404(3) Å, c = 7.095(1) Å, β = 96.10(3)°, Z = 4. The other complexes were characterized by XANES and EXAFS studies, by comparison with analogous complexes of known X-ray crystal structure. The Mn···Mn distances in the dinuclear complexes and in the infinite chains were similar (av 4.5 Å) and longer than for the trinuclear complexes (av 3.6 Å); this is in agreement with the number of carboxylate bridges: two in the first case and three for the trinuclear complexes. All the polynuclear complexes shown very weak antiferromagnetic coupling (J between −0.7 and −3.22 cm-1). So, at low temperatures more than one spin state may be populated and many possible transitions may be expected in the EPR spectra; each series shows a similar spectrum, which is different from the others.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: X-ray Absortion Studies Of [Mn(µ-4-clphcoo) 2 -(Bpy)] N ‚Nh ...mentioning

confidence: 97%

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Synthesis, Structural Characterization (X-ray and EXAFS), and Magnetic Properties of Polynuclear Manganese(II) Complexes with Chlorobenzoato Bridges

et al. 1998

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“…The electronic configuration of manganese atoms embedded in a variety of local structures has been derived from XANES spectra (14, 15). Qualitatively, one may argue that for the calibrating sequence MnO, Mn02, KMn04, the dominant factor for the shift of the edge from that of the metal is the oxidation number, modulated by the configuration of the first coordination shell of oxygen atoms (6;4) (6).…”

Section: Resultsmentioning

confidence: 99%

Precision recording of near-edge profiles of x-ray absorption edges: an improved x-ray spectroscopy

Chiu¹,

Bauer²

1988

Anal. Chem.

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“…It has been shown that the edge shifts to higher energies as the oxidation state increases. 35 For aqueous manganese(II) the absorption edge appears at 6548 eV and in manganese(III)-acetylacetonate the edge is centered at ca. 6559 eV, supporting clearly the presence of a trivalent oxidation state in the 1-3 family.…”

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confidence: 99%

Slow relaxation of the magnetization in Oximato-bridged heterobimetallic Copper(II)-Manganese(III) chains

Ruiz

Castro

Pardo

et al. 2011

J. Braz. Chem. Soc.

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(3), com oxidação do íon manganês(II) a manganês(III) na presença de ar. Na ausência de monocristais para análise por difratometria de raios X, técnicas de absorção de raios X (EXAFS e XANES) foram usadas a 40 K para caracterização estrutural de 1-3. A análise dos dados de absorção de raios X revelou que 1-3 apresentam cadeias bimetálicas de íons Cu II e Mn III ligados por pontes oximato, em ambiente octaédrico (CuN 4 O 2 e MnO 6 ) alongado. Os estudos de propriedades magnéticas de 1-3 revelaram um comportamento metamagnético devido à coexistência de acoplamentos ferromagnéticos intracadeias fortes [J = +52.5 (1), +49.1 (2) e +52.1 cm -1 (3)] e interações antiferromagnéticas intercadeias fracas [j = −0.070 (1), −0.075 (2) e −0.078 cm -1 (3)]. A ortogonalidade estrita entre o orbital magnético do cobre(II) e aquele do centro magnético de manganês(III), junto com a conhecida habilidade do grupo oximato em mediar interações magnéticas quando atua como ponte entre dois íons metálicos, é responsável pela forte interação ferromagnética intracadeia em 1-3. Medidas de susceptibilidade sob corrente alternada realizadas para 1-3 em temperatura baixa e sob campo magnético dc igual a zero revelaram uma dependência do sinal ac fora de fase com a frequência do campo oscilante, como esperado para magnetos do tipo single-chain.The use of the oximato-containing copper(II) complexes, [Cu(Hdeg) (3) where the starting manganese(II) ion was oxidized to manganese(III) by air. In the lack of single crystals suitable for X-ray diffraction analysis, X-ray absorption techniques (EXAFS and XANES) at 40 K were used for the structural characterization of 1-3. The analysis of the X-ray absorption data reveals that 1-3 are oximato-bridged Cu II -Mn III bimetallic chains with elongated octahedral CuN 4 O 2 and MnO 6 surroundings. The study of the magnetic properties of 1-3 reveals a metamagnetic-like behavior due to the coexistence of strong intrachain ferromagnetic couplings [J = +52.5 (1), +49.1 (2) and +52.1 cm -1 (3)] and weak interchain antiferromagnetic interactions [j = −0.070 (1), −0.075 (2) and −0.078 cm -1 (3)]. The strict orthogonality between the magnetic orbital of the copper(II) ion and those of the manganese(III) center, together with the well known ability of the oximato group to mediate magnetic interactions when acting as a bridge between two metal ions, account for the relatively strong intrachain ferromagnetic coupling in 1-3. Alternating current susceptibility measurements for 1-3 in the low temperature range under zero dc magnetic field reveal a frequency-dependence of the out-of-phase ac signal as expected for single chain magnets.Keywords: metal oximates, heterobimetallic complexes, complex as ligand strategy, exchange coupling, single chain magnets Ruiz et al. 977 Vol. 22, No. 5, 2011 IntroductionSince the first report concerning the use of the dimethylglyoxime (H 2 dmg) as a reagent for nickel(II), 1 oximes as ligands have been widely used in coordination chemistry. Although the primary attention on them wa...

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Xanes of Manganese Coordination Complexes

Cited by 3 publications

References 4 publications

Synthesis, Structural Characterization (X-ray and EXAFS), and Magnetic Properties of Polynuclear Manganese(II) Complexes with Chlorobenzoato Bridges

Synthesis, Structural Characterization (X-ray and EXAFS), and Magnetic Properties of Polynuclear Manganese(II) Complexes with Chlorobenzoato Bridges

Precision recording of near-edge profiles of x-ray absorption edges: an improved x-ray spectroscopy

Slow relaxation of the magnetization in Oximato-bridged heterobimetallic Copper(II)-Manganese(III) chains

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