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Journal Articles

Density functional theory study on the $^{193}$ Ir Mssbauer spectroscopic parameters of Vaska's complexes and their oxidative adducts

Kaneko, Masashi; Nakashima, Satoru*

Inorganic Chemistry, 60(17), p.12740 - 12752, 2021/09

https://doi.org/10.1021/acs.inorgchem.1c00239

Times Cited Count：3 Percentile：31.46(Chemistry, Inorganic & Nuclear)

In the present study, density functional theory (DFT) calculation was applied to Vaska's complexes of formula -[IrCl(CO)(PPh $_{3}$ ) $_{2}$ ], and their oxidative adducts with small molecules (YZ) including H $_{2}$ , i.e., -[IrCl(YZ)(CO))(PPh $_{3}$ ) $_{2}$ ], to successfully correlate the electronic states of the complexes with the corresponding $^{193}$ Ir Mssbauer spectroscopic parameters. After confirming the reproducibility of the DFT methods for elucidating the equilibrium structures and $^{193}$ Ir Mssbauer isomer shifts of the octahedral Ir complexes, the isomer shifts and quadrupole splitting values of Vaska's complexes and their oxidative adducts were calculated. A bond critical point analysis revealed that the tendency in the isomer shifts was correlated with the strength of the covalent interaction in the coordination bonds. In an electric field gradient (EFG) analysis of the oxidative adducts, the sign of the principal axis was found to be positive for the complex with YZ = Cl $_{2}$ and negative for the complex with YZ = H $_{2}$ . This reversal of the sign of the EFG principal axis was caused by the difference in the electron density distribution for the coordination bonds between Ir and YZ, according to a density of states analysis.

Journal Articles

Effect of oxygen-donor charge on adjacent nitrogen-donor interactions in Eu $^{3+}$ complexes of mixed N,O-donor ligands demonstrated on a 10-fold [Eu(TPAMEN)] $^{3+}$ chelate complex

Schnaars, K.; Kaneko, Masashi; Fujisawa, Kiyoshi*

Inorganic Chemistry, 60(4), p.2477 - 2491, 2021/02

https://doi.org/10.1021/acs.inorgchem.0c03405

Times Cited Count：6 Percentile：57.56(Chemistry, Inorganic & Nuclear)

To reduce high-level radiotoxic waste generated by nuclear power plants, highly selective separation agents for minor actinides are mandatory. The mixed N,O-donor ligand -tetrakis[(6-carboxypyridin-2-yl)methyl]ethylenediamine (H $_{4}$ TPAEN) has shown good performance as a masking agent in Am $^{3+}$ /Eu $^{3+}$ separation studies. In this work, we examine whether a decrease in O-donor basicity can promote the M $^{3+}$ -N $_{am}$ interactions. Therefore, we replace the deprotonated "charged" carboxylic acid groups of TPAEN $^{4-}$ by neutral amide groups and introduce -tetrakis[(6--diethylcarbamoylpyridin-2-yl)methyl]ethylenediamine (TPAMEN) as a new ligand. TPAMEN was crystallized with Eu(OTf) $_{3}$ and Eu(NO $_{3}$ ) $_{3}$ 6H $_{2}$ O to form positively charged 1:1 [Eu(TPAMEN)] $^{3+}$ complexes in the solid state. Alterations in the M-O/N bond distances are compared to [Eu(TPAEN)] $^{-}$ and investigated by DFT calculations to expose the differences in charge/energy density distributions at europium(III) and the donor functionalities of the TPAEN $^{4-}$ and TPAMEN. On the basis of estimations of the bond orders, atomic charges spin populations, and density of states in the Eu and potential Am and Cm complexes, the specific contributions of the donor-metal interaction are analyzed. The prediction of complex formation energy differences for the [M(TPAEN)] $^{-}$ and [M(TPAMEN)] $^{3+}$ (M $^{3+}$ = Eu $^{3+}$ , Am $^{3+}$ ) complexes provide an outlook on the potential performance of TPAMEN in Am $^{3+}$ /Eu $^{3+}$ separation.

Journal Articles

Complexation and bonding studies on [Ru(NO)(H $_{2}$ O) $_{5}$ ] $^{3+}$ with nitrate ions by using density functional theory calculation

Kato, Akane*; Kaneko, Masashi; Nakashima, Satoru*

RSC Advances (Internet), 10(41), p.24434 - 24443, 2020/06

https://doi.org/10.1039/D0RA05042C

Times Cited Count：6 Percentile：31.01(Chemistry, Multidisciplinary)

Complexation reactions of ruthenium-nitrosyl complexes in HNO $_{3}$ solution were investigated by density functional theory (DFT) calculations in order to predict the stability of Ru species in high-level radioactive liquid waste (HLLW) solution. Equilibrium structure of [Ru(NO)(NO $_{3}$ ) $_{3}$ (H $_{2}$ O) $_{2}$ ] obtained by DFT calculations reproduced the experimental Ru-ligands bond lengths and IR frequencies reported previously. Comparison of the Gibbs energies among the geometrical isomers revealed that the complexation reactions of the ruthenium-nitrosyl complexes with NO $_{3}$ $^{-}$ proceed via the NO $_{3}$ $^{-}$ coordination to the equatorial plane toward the Ru-NO axis. We also estimated Gibbs energy differences on the stepwise complexation reactions to succeed in reproducing the fraction of Ru-NO species in 6 M HNO $_{3}$ solution, such as in HLLW, by considering the association energy between the Ru-NO species and the substituting ligands. Electron density analyses of the complexes indicated that the strength of the Ru-ligands coordination bonds depends on the stability of the Ru species and the Ru complex without NO $_{3}$ $^{-}$ at the axial position is more stable than that wit NO $_{3}$ $^{-}$ , which might attribute to the difference in the trans influence between H $_{2}$ O and NO $_{3}$ $^{-}$ . Finally, we demonstrated the complexation kinetics in the reactions . The present study is expected to enable us to model the precise complexation reactions of platinum-group metals in HNO $_{3}$ solution.

Journal Articles

Density Functional Theory (DFT)-based bonding analysis correlates ligand field strength with $^{99}$ Ru Mssbauer parameters of ruthenium-nitrosyl complexes

Kaneko, Masashi; Kato, Akane*; Nakashima, Satoru*; Kitatsuji, Yoshihiro

Inorganic Chemistry, 58(20), p.14024 - 14033, 2019/10

https://doi.org/10.1021/acs.inorgchem.9b02024

Times Cited Count：12 Percentile：62.96(Chemistry, Inorganic & Nuclear)

We applied density functional theory calculations to ruthenium-nitrosyl complexes, which are known to exist in high-level radioactive waste, to give a theoretical correlation between $^{99}$ Ru Mssbauer spectroscopic parameters ( and $E_{rm Q}$ ) and ligand field strength ( $_{rm o}$ ) for the first time. The structures of the series of complexes, [Ru(NO)L $_{5}$ ] (L = Br $^{-}$ , Cl $^{-}$ , NH $_{3}$ , CN $^{-}$ ), were modeled based on the corresponding single-crystal X-ray coordinates. The comparisons of the geometries and total energies between the different spin states suggested that the singlet spin state of [Ru(II)(NO $^{+}$ )L $_{5}$ ] complexes were the most stable. The calculated results of both the and $E_{rm Q}$ values reproduced the experimental results by reported previously and increased in the order of L = Br $^{-}$ , Cl $^{-}$ , NH $_{3}$ , CN $^{-}$ . Finally, we estimated the ligand field strength ( $_{rm o}$ ) based on molecular orbitals, assuming C $_{rm 4v}$ symmetry and showed the increase of $_{rm o}$ values in that order, being consistent with well-known spectrochemical series of ligands. The increase attributes to the strengthening of the abilities of -donor and -acceptor of the L-ligands to the Ru atom, resulting in the increase of the values.

Journal Articles

On/off spin-crossover phenomenon and control of the transition temperature in assembled Iron(II) complexes

Nakashima, Satoru*; Kaneko, Masashi; Yoshinami, Keisuke*; Iwai, Saki*; Dote, Haruka*

Hyperfine Interactions, 239(1), p.39_1 - 39_15, 2018/12

https://doi.org/10.1007/s10751-018-1512-4

Times Cited Count：2 Percentile：65.67(Physics, Atomic, Molecular & Chemical)

The present study reveals the on/off of spin-crossover (SCO) phenomenon in assembled Fe(II) complexes bridged by bis(pyridyl) type ligand. Whether SCO phenomenon occurs or not in assembled Fe(II) complexes bridged by bis(pyridyl) type ligand is determined by local structure around iron atom. SCO phenomenon occurs when the coordinating pyridines facing to each other across the iron atom are propeller type, while the phenomenon does not occur when they are parallel type or distorted propeller type. DFT calculation explained that, in the shortening of Fe-pyridine bonds when changing from high-spin state to low-spin state, the pyridines of propeller type can approach the iron atom with smaller steric hindrance than those of parallel and distorted propeller type complexes. The local structure is controlled by introducing methyl substituent and introducing -system, changing SCO phenomenon. And the transition temperature of SCO is also controlled in assembled complexes bridged by 1,2-bis(4-pyridyl)ethane by mixing anionic ligand.

Journal Articles

Labeling of bifunctional chelating agent, MAG3, with carrier-free $^{188}$ Re

Hashimoto, Kazuyuki; Wan, K. W. H. B. B.*; Matsuoka, Hiromitsu

Journal of Nuclear and Radiochemical Sciences, 6(3), p.193 - 196, 2005/12

https://doi.org/10.14494/jnrs2000.6.3_193

The radioisotopes of rhenium ( $^{186}$ Re and $^{188}$ Re) are attractive radionuclides for radiotherapy because of their energetic beta particles and gamma rays suitable for imaging. Mercaptoacetyltriglycine, MAG3 (N $_{3}$ S ligand), is a useful bifunctional ligand in labeling monoclonal antibodies with metallic radionuclides. In this study, the labeling of MAG3 with carrier-free $^{188}$ Re from a $^{188}$ W/ $^{188}$ Re generator was investigated in detail. The $^{188}$ Re-MAG3 complex was synthesized by the direct labeling method and by the indirect labeling method using a transfer ligand (citric acid or gluconic acid). The dependence of the labeling yield upon the reaction conditions such as the concentrations of tin(II) chloride dihydrate as a reducing agent, S-benzoyl MAG3 and the transfer ligand, pH, temperature, reaction time and the addition of a carrier was examined. The labeling yield of $^{188}$ Re-MAG3 synthesized by the all method was over 90% under the optimum conditions.

Journal Articles

Novel separation system of trivalent actinides-combined effects of substituted tris(2-pyridylmethyl)amine ligand and hydrophobic counter-anion

Ishimori, Kenichiro*; Watanabe, Masayuki; Kimura, Takaumi; Yaita, Tsuyoshi; Yamada, Takashi*; Kataoka, Yumiko*; Shinoda, Satoshi*; Tsukube, Hiroshi*

Chemistry Letters, 34(8), p.1112 - 1113, 2005/08

https://doi.org/10.1246/cl.2005.1112

Times Cited Count：13 Percentile：44.74(Chemistry, Multidisciplinary)

Stereochemical substitution on tripod ligand significantly offered efficient separation of trivalent actinides from trivalent lanthanides. Liquid-liquid extraction using chiral tris(2-pyridylmethyl)amine ligands as an extractant exhibited high efficiency and selectivity for trivalent actinides. A combination of chiral ligand and 2-bromodecanoic acid further enhanced extraction performance for trivalent actinides.

Journal Articles

Arsenate sorption on schwertmannite

Fukushi, Keisuke*; Sato, Tsutomu*; Yanase, Nobuyuki; Minato, Junichi*; Yamada, Hirohisa*

American Mineralogist, 89(11-12), p.1728 - 1734, 2004/11

http://ammin.geoscienceworld.org/content/89/11-12/1728.abstract

The sorption mechanism of As(V) on schwertmannite was investigated by both a batch sorption experiment and crystallographic considerations. The batch experiment was carried out as a function of As(V) concentration in acidic solution at 25 $^{circ}$ C. Crystallographic considerations indicate surface sites of schwertmannite comprise varied surface oxygen (hydroxyl) and SO $_{4}$ groups. Sorption experiments showed reactive surface sites for As(V) sorption are surface SO $_{4}$ groups. As(V) sorption mechanism involves ligand exchange with solid phase SO $_{4}$ . Results also suggest monodentate As(V) coordination with surface adsorbed SO $_{4}$ sites and bidentate As(V) coordination in structural originated SO $_{4}$ sites. Estimated equilibrium constant for ligand exchange reaction describes the observed As(V) sorption behavior. The surface structure approach in this study reveals reactive surface sites in As(V) sorption on schwertmannite comprise surface SO $_{4}$ group instead of surface hydroxyl groups identified by former views.

Journal Articles

Design of a radiopharmaceutical for the palliation of painful bone metastases; Rhenium-186-labeled bisphosphonate derivative

Ogawa, Kazuma*; Mukai, Takahiro*; Arano, Yasushi*; Hanaoka, Hirofumi*; Hashimoto, Kazuyuki; Nishimura, Hiroshi*; Saji, Hideo*

Journal of Labelled Compounds and Radiopharmaceuticals, 47(11), p.753 - 761, 2004/11

https://doi.org/10.1002/jlcr.864

Times Cited Count：29 Percentile：61.59(Biochemical Research Methods)

no abstracts in English

Journal Articles

Eu(III) adsorption by in the presence of organic ligands

Yoshida, Takahiro; Suzuki, Yoshinori*; Ozaki, Takuo; Onuki, Toshihiko; Francis, A. J.*

Proceedings of International Symposium on Radioecology and Environmental Dosimetry, p.296 - 300, 2004/03

The effects of organic ligands (citric acid, desferrioxamine B (DFO) and ethylenediaminetetraacetic acid (EDTA)) on Eu(III) adsorption by an aerobic bacterium were investigated. After incubation of with 2 M Eu(III) without organic ligands in a 0.1 M NaCl solution containing 3.9 mg $_{dry weight}$ /L biomass for 1 hour, over 90% Eu(III) was adsorbed on the bacterial cells at pH 4 - 7. Eu(III) adsorption by bacterial cells was depleted at pH 4 - 7 when equimolar EDTA was present, while citric acid and DFO showed less effect on the depletion of Eu(III) adsorption. X-ray photoelectron spectroscopy (XPS) indicated that the adsorbed Eu(III) on cells was covalently bound to carboxyl and/or hydroxyl functional groups of the cell surface. These results suggest that carboxyl and/or hydroxyl functional groups of cell surface show a higher affinity with Eu(III) than citric acid and DFO and have the potential to prevent migration of Eu-organic ligands complexes with low stability constants in environments.

Journal Articles

Photoluminescent dinuclear lanthanide complexes with Tris(2-pyridyl)carbinol acting as a new tetradentate bridging ligand

Watanabe, Masayuki; Nankawa, Takuya*; Yamada, Teppei*; Kimura, Takaumi; Namiki, Kosuke*; Murata, Masaki*; Nishihara, Hiroshi*; Tachimori, Shoichi

Inorganic Chemistry, 42(22), p.6977 - 6979, 2003/11

https://doi.org/10.1021/ic034816n

Times Cited Count：34 Percentile：75.23(Chemistry, Inorganic & Nuclear)

A tripodal ligand, tris(2-pyridyl)carbinol affords a novel tetradentate coordination mode in homodinuclear lanthanide complexes, which exhibit remarkably short distance between the metal ions. Strong fluorescence of Eu(III) and Tb(III) complexes with the ligand demonstrate that the ligand has a suitable excited state for energy transfer from the ligand to Eu(III) and Tb(III) center.

Journal Articles

Solid-solution reactions in As(V) sorption by schwertmannite

Fukushi, Keisuke*; Sato, Tsutomu*; Yanase, Nobuyuki

Environmental Science & Technology, 37(16), p.3581 - 3586, 2003/07

https://doi.org/10.1021/es026427i

Times Cited Count：71 Percentile：79.84(Engineering, Environmental)

The mechanism of As(V) sorption on schwertmannite was investigated by a batch sorption experiment as a function of solution As(V) concentration under acidic conditions (pH 3.3 0.1) at 25 $^{circ}$ C. The reacted solution chemistry and mineralogy showed that the mechanism of As(V) sorption was ligand exchange with solid phase SO $_{4}$ in schwertmannite. Two processes presumably occur simultaneously within the reaction period. i.e., ligand exchange of As(V) with surface site SO $_{4}$ and subsequent transfer of As(V) to the structure and ligand exchange with tunnel site SO $_{4}$ . The exchange ratio between As(V) sorption and SO $_{4}$ release, and the SO $_{4}$ coordination environment in schwertmannite indicates that monodentate As(V) coordination occurs in surface sites while bidentate binuclear As(V) coordination occurs in tunnel sites. Sorption modeling that considers the different types of reactive sites successfully described the observed As(V) sorption behavior.

Journal Articles

Magnetic properties of some neptunyl(+1) complexes

Nakamoto, Tadahiro*; Nakada, Masami; Nakamura, Akio

Journal of Nuclear Science and Technology, 39(Suppl.3), p.102 - 105, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875418

no abstracts in English

Journal Articles

Development of novel extractants for actinide separation

Tachimori, Shoichi

Nihon Genshiryoku Gakkai-Shi, 42(11), p.1124 - 1129, 2000/11

https://doi.org/10.3327/jaesj.42.1124

Times Cited Count：1 Percentile：81.71(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Actinide separation with a novel tridentate ligand, diglycolic amide for application to partitioning process

Sasaki, Yuji; Sugo, Yumi; Tachimori, Shoichi

Proceedings of International Conference on Scientific Research on the Back-end of the Fuel Cycle for the 21st Century (ATALANTE 2000) (Internet), 6 Pages, 2000/10

no abstracts in English

JAEA Reports

Effects of ligands on the solubility of tin

Oda, Chie; *

JNC TN8400 98-001, 14 Pages, 1998/11

JNC-TN8400-98-001.pdf:0.38MB

Solubilities of amorphous stannic oxide, SnO $_{2}$ (am) in Na-ClO $_{4}$ -Cl-SO $_{4}$ aqueous systems were measured to quantitatively investigate the influences of the ligands OH $^{-}$ , Cl $^{-}$ and SO $_{4}^{2-}$ on solubilities. They were also measured in bentonite equilibrated solutions to discuss the behavior of tin under a repository condition of a high-revel radioactive waste. The solubility data in sodium perchlorate media in the range of pH from 6 to 11 showed pH dependency, and the hydrolysis constants of tin (IV) were determined (Amaya, et al., 1997). No significant changes in solubilities with the variation in Cl $^{-}$ , SO $_{4}^{2-}$ concentrations were observed in Na-ClO $_{4}$ -Cl-SO $_{4}$ aqueous systems, so this indicates that chloride and sulfate species were less effective than hydroxide complexes. On the other hand, solubilities in bentonite equilibrated solutions were higher than solubilities of other experiments in simple systems. These results suggest that (1) other complexes of tin except hydroxide, chloride or sulfate complexes of tin (IV) may dominantly exist in aqueous phase, (2)solid phase other than SnO $_{2}$ (am) may limit the solubility of tin under repository conditions.