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  • Author or Editor: S. Maeda x
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Abstract  

Iron(III) complexes with the general formula of [Fe (R-Himap)2]X and [Fe(R-Himat)2]X (Himap = shiff-base prepared from the condensation of 4-formylimidazole and 2-aminophenol, Himat = shiff base prepared from the condensation of 4-formylimidazole and 2-aminobenzenethiol, and R = H, Me, Ph; X = ClO4, NO3, BPh4) have been synthesized. The complexes have an N4O2 donor set or an N4S2 donor set. These complexes have 5 and 5 member rings around an iron(III) atom per one chelate ring, that is, "5-5 member rings". The crystal structure, Mössbauer spectra, magnetic properties and absorption spectra of the complexes were examined. In addition, [Fe (Himsa)2]ClO4 having "5-6 member rings" of an N4O2 donor set and [Fe (Ph-Himap)(Ph-imap)] obtained by the deprotonation of [Fe (Ph-Himap)2]ClO4 have been also synthesized, and the Mössbauer spectra and magnetic properties of those complexes were examined. The X-ray structure of a single crystal of [Fe (Himap)2]BPh4 was determined: C44H36N6BO2Fe, triclinic, space group P(# 2), a = 12.452(2) Å, b = 12.748(2) Å, c = 11.996(2) Å, = 103.97(1)°, = 90.78(1)°, = 84.70(1)° and Z = 2. The moiety of an iron atom of [Fe(Himap)2]BPh4 was a pseudo octahedron with an FeN4O2 geometry. [Fe(R-Himap)2]X was in high-spin state (about 5.9 B.M. at 80 K in solid state), and [Fe(R-Himat)2]X was in low-spin state (about 2.0 B.M. at 293 K). The complex [Fe(Himsa)2]ClO4 with "5-6 member rings" and the deprotonated complex [Fe(Ph-Himap)(Ph-imap)] were in the high-spin state (6.0 B.M. at 80 K). It is concluded that the ligand field strength of an N4S2 donor set is stronger than that of an N4O2 donor set.

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Abstract  

We report the temperature dependence of Mössbauer spectra of a mixed-valence dinuclear Fe(II) Fe(III) complex, [Fe2(bpmp)(Ph(CH2)2COO−)2](BF4)2 1, where Hbpmp represents 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol. Two quadrupole doublets observed at 78 K approach each other as the temperature is increased. The two high-energy components of a doublet due to Fe(II) and of that due to Fe(III) become broad in the temperature range from 78 to 230 K and then become narrow above 260 K. The temperature dependence of the spectra was interpreted by assuming of intramolecular electron exchanges between two energetically inequivalent vibronic states FeA(II)FeB(III) and FeA(III)FeB(II) where one of them is slightly more stable than the other.

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Abstract  

Mixed-valence μ-phenolate-bis(μ-carboxylate) diiron(II, III) complex [Fe2(bpmp)(ppa)2](BF4)2 (1) is prepared. The temperature dependence of the Mössbauer spectra of the complex 1 is measured. The Mössbauer parameters of the complex 1 show the unusual increase of isomer shift and quadrupole splitting with an increase in temperature. The spectra are explained by the dynamic electronic states in which the valence states of two iron atoms in a molecule are 2.2 and 2.8 on the Mössbauer time scale at 293 K. The single crystal X-ray structure of the complex 1 is determined at 133 K. The complex 1 crystallizes in the triclinic space group

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1. Two iron atoms in the complex 1 are crystallographycally inequivalent.

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Authors: S. Osaki, Y. Tagawa, T. Chijiiwa, S. Sugihara and Y. Maeda

Abstract  

The35S content in atmospheric deposition, aerosol and rain water was determined about every 10 days for a year with7Be,32P and some stable elements. Average35S concentrations were 110 mBq·m−2·d−1 for atmospheric deposition, 0.078 mBq·m−3 for aerosol in surface air and 45 mBq·l−1 for rain water. The ratios of7Be/35S were abnormally low, although most of32P/7Be showed the reasonable values corresponding to the residence times from 10 to 60 days. The excess35S suggests an external source of35S or/and a faster cycle of35S than that of7Be and32P.

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Abstract  

Leaf and aerosol samples were monthly collected in Mt. Sefuri (Fukuoka Prefecture). Radioactivities of 7Be, 210Pb and 40K were determined with gamma-ray spectrometry. The concentrations of some elements in the leaf samples were determined by neutron activation analysis. Similar seasonal variation of 7Be and 210Pb was observed between leaf and aerosol samples, high in spring and winter and low in summer. Correlation factors for trace elements contained in the leaf show large variations. This indicates that the contribution of two sources (atmospheric deposition and uptake from soil) is very variable.

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Authors: S. Osaki, Y. Tagawa, S. Sugihara, Y. Maeda and Y. Inokura

Abstract  

The concentrations of 7Be, 210Pb and 210Po of ca. 60 parts of a whole tree of Japanese cedar and of underlying litter and soil samples were determined for studying their transfer in a forest canopy. The results suggest that the mean residence times of 7Be and 210Pb in the forest canopy were ca. 20 and 900 days, respectively, and the dry deposition rate of 7Be on the forest canopy was about a half of the total deposition rate.

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Abstract  

Depth distribution of atmospheric 210Pb and 7Be and 90Sr and 137Cs fission products was measured in two types of aeolian soils (desert dust and volcanic ash), irrigated paddy soil and strongly acidic soil. The depth dependence of 210Pb, 7Be and 137Cs show that these radionuclides have been diffused as solid soil particles in surface soil layers. In aeolian soil layers, about 50% of 90Sr were diffused in surface soil layer and the remaining 50% had penetrated to deeper layers. The half of the fission particles containing 90Sr were shown to have decomposed over the past 35 years.

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