Satoshi Matsunaga
Kanagawa University
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Featured researches published by Satoshi Matsunaga.
Journal of the American Chemical Society | 2010
Hitoshi Miyasaka; Natsuko Motokawa; Satoshi Matsunaga; Masahiro Yamashita; Kunihisa Sugimoto; Tatsuya Mori; Naoki Toyota; Kim R. Dunbar
The isostructural series of two-dimensional (2-D) fishnet-type network compounds, [{Ru(2)(O(2)CCF(3))(4)}(2)(TCNQR(x))] x n(solv) (R(x) = H(4), 1; Br(2), 2; Cl(2), 3; F(2), 4; F(4), 5), has been synthesized from the reactions of a paddlewheel diruthenium(II, II) complex, [Ru(2)(II,II)(O(2)CCF(3))(4)], and neutral TCNQ derivatives (TCNQR(x) = 2,3,5,6- or 2,5-halogen-substituted 7,7,8,8-tetracyanoquinodimethane) under anaerobic conditions. Corresponding Rh compounds 1-Rh-5-Rh, which are diamagnetic and redox-inactive, were also synthesized for the purpose of comparison with 1-5. According to the electron affinity of TCNQR(x), which is related to its first reduction potential, the Ru(2) series (1-5) has the requisite driving force for charge transfer from [Ru(2)(II,II)(O(2)CCF(3))(4)] to TCNQR(x), which can lead to a mixed-valence state of [{Ru(2)(4.5+)}-(TCNQR(x)(*-))-{Ru(2)(4.5+)}] for the 2-D network. Such a charge (or electron) transfer results in magnetic exchange interactions between [Ru(2)] units (S = 1 for [Ru(2)(II,II)] and S = 3/2 for [Ru(2)(II,III)](+)) via TCNQR(x)(*-) S = 1/2 radicals that lead to long-range magnetic ordering in the layer. In the present series, only 5 demonstrated the full electron transfer (1-e(-) transfer) to the mixed-valence state, whereas other members are essentially in the state [{Ru(2)(4+)}-(TCNQR(x)(0))-{Ru(2)(4+)}]. Whereas 1-4 are paramagnetic, 5 is a metamagnet undergoing 3-D long-range antiferromagnetic ordering at 95 K (= T(N)) and reverts to a magnetic-field-induced ferromagnetic state exhibiting coercivity up to 60 K. This result is consistent with the fact that TCNQF(4) has the strongest electron affinity among the TCNQR(x) molecules. Even in neutral forms, however, 1-4 can be observed to undergo thermally and/or field-activated charge transfers from [Ru(2)(II,II)] to TCNQR(x) to give semiconductors with an activation energy of 200-300 meV, which is a driving force to transport electrons over the lattice. As determined by their conducting properties, the ease of thermally and/or field-activated charge transfers is on the order of 1 < 4 < 2 approximately = 3 << 5, which is in agreement with the order of electron affinity of TCNQR(x). Indeed, a magnetic anomaly with short-range order associated with the localization of charge-transferred electrons was revealed in the low-temperature susceptibility data for 2 and 3. Finally, 5 was subjected to terahertz time-domain spectroscopy, the data from which revealed that transport hopping electrons scattered at high temperatures interact with magnetically ordered spins with the scattering being suppressed at T(N), at which temperature the real part of the complex electronic conductivity (sigma(1)) and dielectric permeability (epsilon(1)) are dramatically altered. From these collective data, we conclude that molecular design based on an interunit charge transfer in a paramagnetic lattice is an efficient route to the design of materials with synergism between magnetic and conducting properties.
Dalton Transactions | 2013
Takuya Yoshida; Satoshi Matsunaga; Kenji Nomiya
Novel intercluster compounds [{(Au{P(p-RPh)3})2(μ-OH)}2]3[α-PM12O40]2·nEtOH (R = Me, M = W for 1; R = Me, M = Mo for 2; R = F, M = Mo for 3) were synthesized by the polyoxometalate (POM)-mediated clusterization of monomeric phosphanegold(I) complexes, and unequivocally characterized by elemental analysis, TG/DTA, FTIR, X-ray crystallography, and (1)H and (31)P{(1)H} NMR. In each cluster cation, two digold(I) units, {Au{P(p-RPh)3})2(μ-OH)}(+), dimerized to form the tetragold(I) cluster cation by interdimer aurophilic interactions, i.e., a dimer of dinuclear units, and these cations showed different forms of structural dimerization, i.e., a crossed-edge arrangement for 1 and 2 and a parallel-edge arrangement for 3, depending upon the substituent on the aryl group of triarylphosphanes. The dimerization of digold(I) cations was affected by not only the type of the POMs, but also the phosphane ligand of the monomeric phosphanegold(I) precursors.
Dalton Transactions | 2012
Takuya Yoshida; Kenji Nomiya; Satoshi Matsunaga
A novel intercluster compound, [{{Au(PPh(3))}(4)(μ(4)-O)}{{Au(PPh(3))}(3)(μ(3)-O)}][α-PW(12)O(40)]·EtOH (1) constructed between a heptakis{triphenylphosphinegold(i)}dioxonium cation and an α-Keggin polyoxometalate (POM) is synthesized and unequivocally characterized by elemental analysis, TG/DTA, FTIR, X-ray crystallography, solid-state CPMAS (31)P NMR and solution ((1)H, (31)P{(1)H}) NMR. The heptagold(i) cluster was formed during the course of carboxylate elimination of a monomeric phosphinegold(i) carboxylate precursor, i.e., [Au((RS)-pyrrld)(PPh(3))] ((RS)-Hpyrrld = (RS)-2-pyrrolidone-5-carboxylic acid), in the presence of the sodium salt of an α-Keggin POM, Na(3)[α-PW(12)O(40)]·9H(2)O. Compound 1 was formed by ionic interaction between the heptagold(i) cluster cation and the α-Keggin POM anion. The heptagold(i) cluster unit was formed by four inter-cationic aurophilic interactions between the tetragold(i) cluster unit and trigold(i) cluster unit. The tetragold(i) cluster unit and trigold(i) cluster unit contained μ(4)-O and μ(3)-O atoms, respectively.
Inorganic Chemistry | 2018
Kenji Nomiya; Kohei Endo; Yuichi Murata; Shinya Sato; Sho Shimazaki; Shogo Horie; Eri Nagashima; Yuta Yasuda; Takuya Yoshida; Satoshi Matsunaga; Toshiaki Matsubara
Novel intercluster compounds consisting of pentakis[(triphenylphosphane)gold]ammonium(2+) cation (1) and Keggin polyoxometalate (POM) anions, i.e., {[Au(PPh3)]5(μ5-N)}3[α-PM12O40]2 (1-PW for M = W; 1-PMo for M = Mo), were synthesized in 30-36% yield by one-pot reaction of the protonic acid form of the Keggin POMs, H3[α-PM12O40]·nH2O (n = 13 for M = W; n = 15 for M = Mo) with monomeric (triphenylphosphane)gold(I) carboxylate [Au(RS-pyrrld)(PPh3)] [RS-Hpyrrld = (RS)-2-pyrrolidone-5-carboxylic acid] in the presence of aqueous NH3 at a molar ratio of 2:15:x (x = 3 for 1-PW; x = 7.5 for 1-PMo). These compounds resulted from the nitrogen-centered phosphanegold(I) clusterization of in situ generated monomeric phosphanegold(I) units, [Au(PPh3)]+ or [Au(L)(PPh3)]+ (L = NH3 or solvent), during the carboxylate elimination of [Au(RS-pyrrld)(PPh3)] in the presence of the Keggin POMs and aqueous NH3. The products 1-PW and 1-PMo were characterized by elemental analysis, Fourier transform infrared, thermogravimetric and differential thermal analyses (TGA/DTA), X-ray crystallography, and solid-state cross-polarization magic-angle-spinning (CPMAS) (31P and 15N) and solution (31P{1H} and 1H) NMR spectroscopy. The lattice contained three independent {[Au(PPh3)]5(μ5-N)}2+ cations, of which two took regular trigonal-bipyramidal (TBP) geometries and the third took a distorted, square-pyramidal (SP) geometry. These geometries are in contrast to those reported by Schmidbaurs group for {[Au(PPh3)]5(μ5-N)}2+ cations as BF4 salts. Density functional theory and ONIOM calculations for {[(L3P)Au]nN}(n-3)+ (L = H or Ph; n = 4-6) showed that the pentacoordinate cluster is energetically most stable and its TBP structure is only 1.6 kcal mol-1 more stable than its SP structure, in accordance with the experimental facts.
Journal of the American Chemical Society | 2010
Natsuko Motokawa; Satoshi Matsunaga; Shinya Takaishi; Hitoshi Miyasaka; Masahiro Yamashita; Kim R. Dunbar
European Journal of Inorganic Chemistry | 2011
Kenji Nomiya; Yoshitaka Sakai; Satoshi Matsunaga
European Journal of Inorganic Chemistry | 2011
Satoshi Matsunaga; Nanako Endo; Wasuke Mori
European Journal of Inorganic Chemistry | 2012
Satoshi Matsunaga; Nanako Endo; Wasuke Mori
Bulletin of the Chemical Society of Japan | 2006
Masahiro Yamashita; Kouichi Takizawa; Satoshi Matsunaga; Daisuke Kawakami; Hiroaki Iguchi; Shinya Takaishi; Takashi Kajiwara; Fumiyasu Iwahori; Tomohiko Ishii; Hitoshi Miyasaka; Ken-ichi Sugiura; Hiroyuki Matsuzaki; Hideo Kishida; Hiroshi Okamoto
Journal of Molecular Catalysis A-chemical | 2014
Hiroki Aoto; Keisuke Matsui; Yoshitaka Sakai; Teppei Kuchizi; Hiromi Sekiya; Hironori Osada; Takuya Yoshida; Satoshi Matsunaga; Kenji Nomiya