Publications by authors named "Masayuki Koikawa"

Article Synopsis
  • Researchers synthesized cyclic trinuclear metal complexes, including two homo-metal complexes [{Fe(LBr)py}] and [{Mn(LBr)(py) MeOH}], and one hetero-metal complex [FeMn(LH)(DMF)] using special asymmetric ligands.
  • The molecular structure of one of the complexes features a unique tripod design with three-fold symmetry, leading to a dimeric capsule roughly measuring 3 × 1.6 × 1.6 nm.
  • Magnetic studies indicated weak antiferromagnetic interactions between the metal ions in one of the complexes, providing insights into their magnetic properties.
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Trinuclear metallacyclic oxidovanadium(V) complexes, [{VO(LR)}] (-) with asymmetric multidentate linking ligands (HLR: R = H, Me, Br), were synthesized. The molecular structure of is characterized as a tripod structure, with each V(V) ion coordinated by -atoms from a tridentate Schiff base site and -atoms from a bidentate benzoxazole site of two respective HLH ligands. The intramolecular V⋯V distances range from 8.

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Pentakis(dimethylsulfoxide-κ)oxidovanadium(iv) bis(tetraphenylborate), [VO(dmso)][BPh] (dmso: dimethylsulfoxide), was synthesized, and its pseudo- VO coordination geometry was revealed by a single-crystal X-ray method. A novel equation set was obtained for magnetic susceptibility and magnetization of the d complexes, considering the axial distortion and the spin-orbit coupling for the D free-ion term. The equation set enabled magnetic simulation for significantly symmetry-lowered d complexes to obtain the anisotropic -values and also the excitation energies.

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The magnetostructural correlation of the hexakis-dmso cobalt(ii) complex, [Co(dmso)](BPh) (dmso: dimethylsulfoxide), was investigated by single-crystal X-ray diffraction study and magnetic measurements. The magnetic analysis concluded the negative Δ value (H = Δ(L - 2/3) + E(L - L) - (3/2)κλL·S + β[-(3/2)κL + gS]·H (u = x, y, z)), and this was explained by the tetragonal elongation of the octahedral geometry. The magnetostructural correlation was ascertained by both the angular overlap model calculation and the density functional theory calculation.

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Four Zn(II) ions arranged within a pyridine-modified large phenolate-containing macrocyle Lpy2- encapsulate two chloranilate ions in a double bis-didentate bridging fashion; the ligands are strongly pi-pi stacked with each other with a short distance of 3.27 A and are electrochemically reduced at the same potential of -1.00 V to produce a reasonably stable biradical species with T1/2 = 60 min at 25 degrees C.

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