Publications by authors named "Kiyotaka Mitsumoto"

A TTF-based (TTF=tetrathiafulvalene) tridentate ligand (α-(4'-methyl-4,5-di-n-dodecylthylthiotetrathiafulvalene-5'-ylthio)- α'-[2,2,2-tris(1-pyrazolyl)ethoxy]-p-xylene) (L) with long-chain alkyl moieties was prepared in order to obtain a new multi-redox active gelator based on a mixed-metal octanuclear complex [Fe Ni (CN) (tp) (L) ](BF ) (1). The magnetism, electrochemistry, and gelation behavior of 1 were studied and 1,2-dichlorobenzene solutions of 1 are shown to display thermoreversible gelation behavior at room temperature. Furthermore, the gel phase of 1 was shown to undergo room-temperature gel-to-sol transformations induced by both the oxidation and reduction of the gelator complex by F TCNQ or [Fe (Cp*) ], respectively.

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A bulky bidentate ligand was used to stabilize a macrocyclic [Fe(III)8Co(II)6] cluster. Tuning the basicity of the ligand by derivatization with one or two methoxy groups led to the isolation of a homologous [Fe(III)8Co(II)6] species and a [Fe(III)6Fe(II)2Co(III)2Co(II)2] complex, respectively. Lowering the reaction temperatures allowed isolation of [Fe(III)6Fe(II)2Co(III)2Co(II)2] clusters with all three ligands.

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A nonanuclear copper grid complex, [Cu(II)9(L)6](BF4)6·1-PrOH·5H2O (1·1-PrOH·5H2O; L = 2,6-bis[5-(2-pyridinyl)-1H-pyrazol-3-yl]pyridine), was synthesized with a [3 × 3] grid structure consisting of nine Cu(II) ions and six deprotonated ligands and displayed four-step quasi-reversible redox behavior from [Cu(II)9] to [Cu(I)4Cu(II)5]. The corresponding heterovalent complex [Cu(I)2Cu(II)7(L)6](PF6)4·3H2O (2·3H2O) was successfully isolated and had a distorted core structure that radically changed the intramolecular magnetic coupling pathways.

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New TTF-based (TTF = tetrathiafulvalene) ligands, L1 and L2 (L1 = α-(4'-methyl-4,5-ethylenedithiotetrathiafulvalene-5'-thio)-α'-[tris-2,2,2-(1-pyrazolyl)ethoxy]-p-xylene and L2 = α-(4'-methyl-4,5-dimethylthiotetrathiafulvalene-5'-thio)-α'-[tris-2,2,2-(1-pyrazolyl)ethoxy]-p-xylene), possessing tris-pyrazolyl coordination sites, were synthesized. The reactions of Ni(BF(4))(2)·6H(2)O with the TTF-ligands (L1 and L2), n-Bu(4)N[Fe(CN)(3)(tp or pztp)] (tp = hydrotris(pyrazol-1-yl)borate and pztp = tetrakis(pyrazol-1-yl)borate) in the presence of additional counter ions afforded two cyanide-bridged octanuclear complexes: [Fe(III)(4)Ni(II)(4)(CN)(12)(pztp)(4)(L1)(4)](BF(4))(4) (1) and [Fe(III)(4)Ni(II)(4)(CN)(12)(pztp)(4)(L2)(4)](PF(6))(4) (2). Using a similar procedure to that employed in the synthesis of complex 2, with the addition of sodium tetraphenylborate, yielded a two-electron-reduced compound, Na[Fe(III)(2)Fe(II)(2)Ni(II)(4)(CN)(12)(tp)(4)(L2)(4)](BF(4))(3) (3), in which a sodium ion was encapsulated by the cube.

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Cyanide-bridged metal complexes of [Fe(8)M(6)(μ-CN)(14)(CN)(10)(tp)(8)(HL)(10)(CH(3)CN)(2)][PF(6)](4)⋅n CH(3)CN⋅m H(2)O (HL=3-(2-pyridyl)-5-[4-(diphenylamino)phenyl]-1H-pyrazole), tp(-) =hydrotris(pyrazolylborate), 1: M=Ni with n=11 and m=7, and 2: M=Co with n=14 and m=5) were prepared. Complexes 1 and 2 are isomorphous, and crystallized in the monoclinic space group P2(1)/n. They have tetradecanuclear cores composed of eight low-spin (LS) Fe(III) and six high-spin (HS) M(II) ions (M=Ni and Co), all of which are bridged by cyanide ions, to form a crown-like core structure.

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