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Two tetranuclear Co(II) complexes, [Co4(pmab)4Cl4] (1) and [Co4(pmab)4(OBz)2]Cl2 (2) [Hpmab = 2-{(p-pyridinylmethylene)amino}benzenemethanol], have been synthesized and characterized through single-crystal X-ray diffraction, IR and UV-VIS spectroscopy, and magnetic measurements. Structural analysis revealed that both complexes possess a [Co4O4] cubane-like metal core connected by μ3-alkoxo bridges. Magnetic measurements of Complex 1 indicate weak ferromagnetic interactions (J ~ +0.75 cm−1) within the tetranuclear core, while Complex 2 exhibits antiferromagnetic behavior due to the presence of syn-syn bridging benzoate ligands. Alternating current (AC) magnetic measurements suggest that Complex 1 exhibits slow magnetic relaxation behavior. [ABSTRACT FROM AUTHOR]

Cyclic trinuclear homo-metal complexes, [{Fe(L3+2Br)py}3] (1) and [{Mn(L3+2Br)}3(py)2 MeOH] (2), along with a hetero-metal complex, [FeMn2(L3+2H)3(DMF)3] (3), were synthesized using asymmetric ditopic ligands (H3L3+2H: 2-(2-hydroxyphenyl)-6-ol-5-(salicylideneamino)benzoxazole, H3L3+2Br: 2-(2-hydrox-5-bromoyphenyl)-6-ol-5-(5-bromosalicylideneamino)benzoxazole). The molecular structure of 1 is characterized by a tripod structure with three-fold symmetry, where an enantiomer pair forms a dimeric capsule with dimensions of approximately 3 × 1.6 × 1.6 nm3. Complexes 2 and 3, which lack three-fold symmetry, exhibit similar molecular structures to previously reported complexes with these ligands, but do not form a capsule structure. Magnetic measurements of 1–3 reveal the presence of significantly weak antiferromagnetic interactions between the metal ions. [ABSTRACT FROM AUTHOR]

Carboxylato-bridged dinuclear and tetranuclear Mn(II) complexes 1–3 with ditopic ligands featuring two N3-terminal coordination sites connected by hexyl (tphn), octyl (tpon), and p-xylyl (tpxn) linkers have been synthesized and characterized through X-ray single-crystal structure analyses, infrared spectroscopy, and elemental analyses. Complex 1 is a μ-fluorido-bis-μ-acetato dinuclear Mn(II) complex where the ligand tphn coordinates to both terminal sides of a dinuclear Mn unit. In contrast, complexes 2 and 3 are tetranuclear Mn(II) complexes with a macrocyclic structure, in which two dinuclear Mn units are linked by ligands tpon or tpxn. The redox behaviors of 1 and 2 were elucidated by cyclic voltammetry, revealing two metal-centered redox processes corresponding to Mn2(II,II)/Mn2(II,III) and Mn2(II,III)/Mn2(III,III). [ABSTRACT FROM AUTHOR]

A mononuclear Ni(II) complex, [Ni(HL1)2], (1) and a novel tetranuclear heterometal Mn-Ni complex, [Mn3Ni(L1)4Cl2(EtOH)2], (2) [H2L1 = N-(2-hydroxymethylphenyl)salicylideneimine], have been synthesized and characterized via X-ray crystal structure analyses, infrared spectra, and elemental analyses. The structure analyses revealed that the tridentate ligand, H2L1, coordinates in a facial mode for Ni and a mer mode for Mn, respectively. Complex 2 includes Mn(II)Mn(III)2Ni(II) tetranuclear metal core bridged by μ-phenoxo and μ-alkoxo oxygens. Magnetic measurements for 2 indicate that weak ferromagnetic interactions (JMn(III)Ni(II) = 2.23, JMn(III)Mn(II) = 0.46, JMn(II)Ni(II) = 1.78, and JMn(III)Mn(III) = 0.58 cm−1) dominate in the tetranuclear core. Additionally, in alternating current (AC) magnetic measurements, frequency-dependent out-of-phase responses were observed. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis of sterically hindered tris-pyridyl methane ligands. The mechanism for their hydroxylation in the reaction with CuBr (sub)2 in MeOH under air is analyzed.

Chemical research has established dicopper complexes with new dinucleating tetraimidazole heptadentate ligands 1,5-bis[bis[(1-methyl-4-imidazolyl)methyl]amino]-3-pentanol and 1,5-bis[bis[(1-isopropyl-4-imidazolyl)methyl]amino]-3-pentanol. The synthesis process involves the reductive coupling of 1,5-diamino-3-pentanol with four equiv of 1-alkyl-4-formylimidazole using sodium cyanoborohydride in quantitative yields.

Heterodinuclear macrocycic CuIIPbII complexes containing two 2, 6-bis(iminomethyl)-4-methylphenolates joined by two lateral chains at the imino nitrogen are synthesized. The complex has the formula CuPb(L)XY, where L2- = L1 for m = 2, L2 for m = 3 and XY = (ClO4)2, (NO3)(PF6), (AcO)(BPh4). The structural analyses for the compound (CuPb(L1))(AcO)(BPh4).DMF and its Mn analogue are discussed. In addition, a series of CuIIMII complexes using Mn, Fe, Co, Ni, Cu and Zn are prepared and characterized.

A new group of ferromagnets was generated by a synthesis reaction between the eta(super3)-complex having D(sub3)symmetry, a metal(II) salt and tetra(n-butyl)ammonium bromide at room temperature. The new compounds possess ferromagnetic attributes, including high magnetic force at low temperatures, changes in magnetic phases with temperature fluctuations, formation of magnetic loops at 5 Kelvin and magnetization values of about 7.5 T at 4.2 Kelvin.

Pentakis(dimethylformamide-κO)oxidovanadium(IV) bis(hexafluoridophosphate), [VO(dmf)5][PF6]2 (dmf: dimethylformamide), was synthesized, and its crystal structure was revealed by a single-crystal X-ray method. The [VO(dmf)5]2+ complex cation dimerized in the crystal, and a weak ferromagnetic interaction was attributed to the dimerized structure. In addition, conformational prediction was successfully conducted using the enumeration result on the basis of group theory. As a result, a reasonable monomer structure of the defect-S6 symmetry was obtained as the most stable structure in dilute solution; in addition, a dimer structure was predicted as the structure in a crystal. [ABSTRACT FROM AUTHOR]