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| 1.
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Ihara, Yoshinori ; Uehara, Akira ; Tsuchiya, Ryokichi ; Kyuno, Eishin
概要:
The following six cobalt(III) complexes containing phenylbiguanide were prepared and the thermal reactions were followed
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both isothermally and non-isothermally (derivatographically) in the solid phase: trans-[Co(A)2(phbgH)2]X3·n2O, where A denotes volatile ligands such as NH3, CH3NH2 or C5H5N; phbgH denotes 1-phenylbiguanide, X chloride or bromide ion; and n is 2 or 3. From the electronic, IR and far-IR spectra and magnetic susceptibilities of these complexes before and after heating, the products obtained by evolving volatile ligands were found to be uniform bivalent cobalt complexes without rupture of the bonds of phbgH to cobalt in spite of the reduction of central cobalt(III) ion, except for the complexes containing ammonia. The reaction seems to be caused by the electron transfer from the coordinated phbgH to cobalt, not from the outer-sphere anions.
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| 2.
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Ihara, Yoshinori ; Izumi, Eiichi ; Uehara, Akira ; Tsuchiya, Ryokichi ; Nakagawa, Shigeo ; Kyuno, Eishin
概要:
Thermal reactions of the [Ni(H2O)2(AA)2]X2·nH2O complexes in a solid phase were investigated, where AA is N,N′-diethylet
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hylenediamine (NN′-deen), N,N-dimethylethylenediamine (NN-dmen), or N,N′-dimethylethylenediamine (NN′-dmen), and where X− is Cl−, Br−, I−, NO3− or ClO4−. By means of thermal analyses and spectral and magnetic measurements in a series of these complexes before and after heating, the following results were obtained. In the case of the NN′-deen complexes, only the perchlorate deaquates to change from octahedral to square-planar, but the other salts, such as the chloride, bromide, iodide, and nitrate, undergo deaquation-anation keeping their octahedral configuration. The deaquation-anation was also observed in the chloride, bromide, and nitrate of the NN-dmen complexes, but the iodide deaquated, and so was transformed from octahedral to square-planar. In the NN′-dmen complexes, only deaquation-anation was detected, irrespective of the anions (Cl−, Br−, I−, and NO3−). The effects of N-substituents in the diamines and the anions on the above transformation were discussed.
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| 3.
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Ihara, Yoshinori ; Satake, Yasuhiro ; Suzuki, Masatatsu ; Uehara, Akira
概要:
The thermochemical changes in coordination structure of diaquabis(N,N- or N,N′,-dialkylethylenediamine)nickel(II) comple
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xes ([Ni(H2O)2(diamine)2]X2·nH2O) were reinvestigated by means of TG-DTA and electronic spectroscopy at room and elevated temperatures, where diamine is N,N (or N,N′-dimethylethylenediamine (NN- or NN′-dmen) or N,N-(or N,N′)-diethylethylenediamine (NN- or NN′-deen); X is Cl−, Br−, I−, or NO3−; n is 0, 1, 2, or 3. The diaqua complexes prepared were all trans except for cis-[Ni(H2O)2(NN-dmen)2]I2. The trans complexes with the symmetric (N,N′-dialkylsubstituted) diamines brought about a deaquation-anation upon heating, retaining the original trans configuration, while those with the asymmetric (N,N-dialkylsubstituted) diamines transformed into the cis complexes. In the case of the NN-dmen complexes, cis-halogenoaqua species were isolated as a stable intermediate during the thermal reactions. The complex nitrates changed to trans-dinitrato or cis-mononitrato species depending upon the diamines. The effects of the N-substituents in the diamines and of the anions on the patterns of thermal reactions were also discussed.
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| 4.
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Ihara, Yoshinori ; Satake, Yasuhiro ; Fujimoto, Yumi ; Senda, Hitoshi ; Suzuki, Masatatsu ; Uehara, Akira
概要:
The structures of two diaquabis(N,N-dialkylethylenediamine)nickel(II) chlorides ([Ni(H2O)2(diamine)2]Cl2·nH2O) were dete
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rmined by X-ray crystallographic studies, where diamine is N,N-dimethylethylenediamine(NN-dmen) or N,N-diethylethylenediamine (NN-deen). Both complexes are trans and crystallize in the monoclinic space group P21⁄n. The unit cell parameters of the NN-dmen complex, NiCl2C8N4O2H32, are a=7.531(1), b=13.092(1), c=9.591 Å, β=107.76(1)°, and Z=2, and those of the NN-deen complex, NiCl2C12N4O2H36, are a=9.154(1), b=8.692(1), c=12.395(2) Å, β=104.46(1)°, and Z=2. In trans-[Ni(H2O)2(NN-dmen)2]Cl2·2H2O and trans-[Ni(H2O)2(NN-deen)2]Cl2, the Ni–NMe2 and Ni–NEt2 bond distances (2.183 and 2.271 Å) are much longer than the Ni–NH2 distances (2.078 and 2.064 Å), forming tetragonally distorted octahedrons with four close in-plane neighbors(N2O2) and two remote axial ones(N2). It is apparent that this distortion originates from the steric requirement of N-substituted groups. Such a distortion significantly affects the electronic spectra of these complexes.
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| 5.
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Suzuki, Masatatsu ; Uehara, Akira
概要:
Reaction of copper(II) ion with hexacyanoferrate(II) ion, [Fe(CN)6]4−, in an aqueous solution containing such an amine a
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s en (1,2-ethanediamine), tn (1,3-propanediamine), dien (bis(2-aminoethyl)amine), or dpt (bis(3-aminopropyl)amine), gave two types of complexes: Double complex salts, [Cu(en or tn)2]2[Fe(CN)6]·nH2O(n=5–8), and cyanide-bridged complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O. The infrared spectra of the complexes in the νCN region revealed that the complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, contain cyanide bridges, while in [Cu(en or tn)2]2[Fe(CN)6]·nH2O, no cyanide bridge is present. The thermal reactions of the complexes in the solid state were investigated by means of derivatography under dynamic conditions (D conditions). It was found that dehydration from [Cu(en)2Fe(CN)6]·nH2O resulted in formation of cyanide bridge in the apical position of square planer [Cu(en)2]2+. For [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, dehydration resulted in the formation of additional cyanide bridges. All the complexes showed metal to metal (iron(II) to copper(II)) charge-transfer transitions (MMCT) in the near ultraviolet or visible region. The complexes, [Cu(en or tn)2]2[Fe(CN)6]·nH2O, exhibited the outer sphere iron(II) to copper(II) charge-transfer bands (OSMMCT) in the near ultra-violet region. [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O and the dehydrated complexes prepared by thermal reaction showed the inner-sphere iron(II) to copper(II) charge transfer bands (ISMMCT) in the visible region. A good correlation was observed between the energies of the MMCT and the d-d band maxima of copper(II) ions.
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| 6.
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Kayatani, Takayuki ; Hayashi, Yoshihito ; Suzuki, Masatatsu ; Inomata, Katsuhiko ; Uehara, Akira
概要:
A dicopper(II) complex with a novel unsymmetric dinucleating ligand, H2L-1, which can provide donor atom, coordination n
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umber, and geometric asymmetries at metal centers, [Cu2(L-1)(CH3COO)]ClO4·H2O·0.5NaClO4 (1), was synthesized, where H2L-1 is a racemic 1-bis(2-pyridylmethyl)amino-3-salicylideneaminopropan-2-ol. The ligand is a hybrid one of 1,3-bis[bis(2-pyridylmethyl)amino]propan-2-ol (Htpdp) and 1,3-bis(salicylideneamino)propan-2-ol (H3L-2). Crystal structure of 1 was determined by X-ray crystallography. Complex 1 crystallizes in monoclinic space group C2/c with a = 42.704(8), b = 12.689(6), c = 29.008(9) Å, β = 128.28(1)°, and Z = 16. The crystal structure showed that two stereoisomers (1a and 1b) are present in solid state. This is attributable to the presence of an enantiomeric pair of L-1. Dinuclear cations consist of one square-planar site with a NO3 donor set and one five-coordinate site with a N3O2 donor set, which are linked by an endogenous alkoxide bridge of L-1 and an exogenous acetate bridge. A powdered sample of 1 shows weak antiferromagnetic interaction (2.60 B.M./Cu2 at 300 and 1.81 B.M./Cu2 at 5 K). Cryomagnetic data is analyzed using two exchange coupling constants, J1 = −0.18 cm−1 and J2 = −9.05 cm−1. EHMO calculations revealed that the observed weak antiferromagnetic interaction(s) compared with that found for [Cu2(L-2)(CH3COO)] (3) (J = −85 cm−1) is reasonably interpreted in terms of the energy gap and the nature of HOMO and LUMO. Some other physicochemical properties of the complex are discussed in comparison with those of the parent complexes, [Cu2(tpdp)(CH3COO)]2+ (2) and [Cu2(L-2)(CH3COO)] (3).
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| 7.
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Suzuki, Masatatsu ; Sugisawa, Toshiharu ; Uehara, Akira
概要:
Two dinuclear cobalt(II,II) complexes, [Co2(tpdp)(CH3COO)](ClO4)2·0.5H2O (1) and [Co2(tmdp)(CH3COO)](ClO4)2·H2O (2), wer
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e prepared, where Htpdp and Htmdp are 1,3-bis[bis(2-pyridylmethyl)amino]-2-propanol and 1,5-bis[bis(2-pyridylmethyl)amino]-3-pentanol respectively. Their electronic spectral and magnetic data revealed that 1 and 2 are five-coordinate in the high-spin state, in the same manner as [Co2(bpmp)(CH3COO)]2+ (3) (Hbpmp=2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol). The complexes reacted with molecular oxygen to form μ-peroxo complexes in dichloromethane and acetonitrile. The oxygen affinity of the complexes decreased in the order of 3>2>1. The relationships between the oxygen affinities and (1) the donor abilities of dinucleating ligands, (2) the energies of the charge-transfer bands (O22− to Co3+) of the μ-peroxo complexes, and (3) the redox potentials of the Co3+–O2−–Co3+/Co3+–O22−–Co3+ couple indicated that a steric effect arising from the dinucleating ligands contributes significantly to the oxygen affinities of the complexes.
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| 8.
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Sugimoto, Hideki ; Nagayama, Toshihiko ; Maruyama, Sachihito ; Fujinami, Shuhei ; Yasuda, Yuichi ; Suzuki, Masatatsu ; Uehara, Akira
概要:
A new dinucleating ligand containing a sterically bulky imidazolyl group, Ph-Htidp (N,N,N′,N′-tetrakis[(1-methyl-4,5-dip
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henyl-2-imidazolyl)methyl]-1,3-diamino-2-propanol), and its μ-alkoxo-diiron(II) complexes [Fe2(Ph-tidp)(RCO2)](ClO4)2, (RCO2 = C6H5CO2 (1), C6F5CO2 (2), CF3CO2 (3), and C2H5CO2 (4)), were synthesized. The structure of complex 1 was determined by X-ray crystallography. Complex 1 crystallizes in the monoclinic space group P21/c with a = 13.464(2), b = 19.223(4), c = 31.358(4) Å, β = 92.84(2)°, and Z = 4. The complex has a doubly-bridged structure with μ-alkoxo of Ph-tidp and μ-benzoate; the two iron centers have a distorted five-coordinate structure with N3O2 donor set. All the complexes showed fairly good reversible oxygenation below −30 °C in CH2Cl2, which was monitored by UV-vis and NMR spectroscopies, and dioxygen up-take measurements. Introduction of 4,5-diphenyl substituents into 2-imidazolyl group stabilized the μ-peroxo diiron species against irreversible oxidation, just as introduction of 6-methyl substituent into 2-pyridyl group did. Phenyl substituents appear to weaken the electron donor ability of a dinucleating ligand to stabilize divalent oxidation state of iron and to form a hydrophobic cavity for a O2 binding site, which would suppress the irreversible oxidation and facilitate the reversible oxygenation. Dioxygen affinities of the Ph-tidp and Me4-tpdp diiron(II), and the tpdp and bpmp dicobalt(II) complexes were measured, [Fe2(Me4-tpdp)(RCO2)]2+ (RCO2 = C6H5CO2 and RCO2 = CF3CO2) and [Co2(L)(RCO2)]2+ (L = tpdp, RCO2 = CH3CO2, and L = bpmp, RCO2 = C6F5CO2, and CF3CO2), where Me4-tpdp, tpdp, and bpmp are N,N,N′,N′-tetrakis[(6-methyl-2-pyridyl)methyl]-1,3-diamino-2-propanolate, N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,3-diamino-2-propanolate, and 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenolate, respectively. Within a series of the Ph-tidp diiron(II) complexes, dioxygen affinity is well correlated with electron donor ability of bridging carboxylates (1 (C6H5CO2) > 2 (C6F5CO2) > 3 (CF3CO2)). In contrast to the above trend, dioxygen affinities of the Ph-tidp complexes are lower than those of the Me4-tpdp complexes, although electron donor abilities of the Me4-tpdp complexes are weaker than those of the Ph-tidp complexes. Significant enhancement of dioxygen affinity was observed for both iron and cobalt complexes with 2,6-bis(aminomethyl)phenolate bridging skeleton compared to the complexes with a 1,3-diamino-2-propanolate bridging one. Thermodynamic study suggested that the observed enhancement is mainly attributable to a favorable entropy effect along with a steric effect.
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| 9.
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Hishiki, Masanobu ; Suzuki, Masatatsu ; Uehara, Akira
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| 10.
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Uehara, Akira ; Tsuchiya, Ryokichi
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