Structures of Dimer-of-Dimers Type Defect Cubane Tetranuclear Copper(II) Complexes with Novel Dinucleating Ligands

Abstract

Only a limited number of multinucleating ligands can stably maintain multinuclear metal structures in aqueous solutions. In this study, a water-soluble dinucleating ligand, 2,6-bis{[N-(carboxylatomethyl)-N-methyl-amino]methyl}-4-methylphenolate ((sym-cmp)3−), was prepared and its copper(II) complexes were structurally characterized. Using the single-crystal X-ray diffraction method, their dimer-of-dimers type defect cubane tetranuclear copper(II) structures were characterized for [Cu4(sym-cmp)2Cl2(H2O)2] and [Cu4(sym-cmp)2(CH3O)2(CH3OH)2]. In the complexes, each copper(II) ion has a five-coordinate square-pyramidal coordination geometry. The coordination bond character was confirmed by the density functional theory (DFT) calculation on the basis of the crystal structure, whereby we found the bonding and anti-bonding molecular orbitals. From the cryomagnetic measurement and the magnetic analysis, overall antiferromagnetic interaction was observed, and this magnetic behavior is also explained by the DFT result. Judging from the molar conductance and the electronic spectra, the bridging chlorido ligand dissociates in water, but the dinuclear copper(II) structure was found to be maintained in an aqueous solution. In conclusion, the tetranuclear copper(II) structures were crystallographically characterized, and the dinuclear copper(II) structures were found to be stabilized even in an aqueous solution.

Relationship between Structure and Zero-Field Splitting of Octahedral Nickel(II) Complexes with a Low-Symmetric Tetradentate Ligand

“…Bis(2-methoxyethyl)amine was supplied by Tokyo Chemical Industry Co., Ltd., Tokyo, Japan, Sodium tetraphenylborate was supplied by FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan. H(onp) was prepared by refluxing the ethanolic solution (10 mL) of paraformaldehyde (1.51 g, 50.3 mmol), bis(2methoxyethyl)amine (6.66 g, 50.0 mmol), and p-nitrophenol (7.01 g, 50.4 mmol) for 29 h (yield 12.02 g, 42.28 mmol, 84.6%), based on the literature method [16]. The IR spectra of H(onp) are shown in Figure S1.…”

Synthesis and Characterization of a New Cu(II) Paddle-Wheel-like Complex with 4-Vinylbenzoate as an Inorganic Node for Metal–Organic Framework Material Design

“…Several copper systems have two or more copper ions at the active site, with functions that cannot be achieved by one copper ion alone. Thus, the synthesis of materials like MOFs with multiple copper ions in their structure is of scientific interest to further our understanding of certain biochemical mechanisms and for their potential use as functional materials [ 11 , 12 , 13 ]. In particular, Cu-MOFs are used for the adsorption of carbon dioxide, methane, and nitrogen [ 14 ].…”

Novel Tetranuclear Heterometallic Mn3Ni and Mononuclear Ni Complexes with an ONO Schiff Base Ligand: Synthesis, Crystal Structures, and Magnetic Properties

“…The field of molecular magnetism in discrete polynuclear complexes has seen significant research over the last few decades [1][2][3][4][5][6]. This research covers a wide range of objectives, from a fundamental understanding of the correlation between spin-exchange interactions and molecular structure [1,2,[7][8][9][10] to the development of functional magnetic materials like single-molecule magnets (SMMs) [3][4][5][6]11,12]. While the study of homometallic complexes is well-established, the exploration of heterometallic complexes remains relatively limited.…”