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The preparation and crystal structure analyses of 1,2,3-triazole fused p-benzoquinone derivatives were performed conventionally from electronically active tetraamino-p-benzoquinone (1). The redox behaviour and crystal structure of 1 were compared with those of chemically stable strong electron donor tetrakis(dimethylamino)-p-benzoquinone (3). The reaction of 1 with NaNO2 generated a diazonium salt, which reacted further to give residual amino groups of 1, forming bis(1,2,3-triazole)-p-benzoquinone (2) in high yield. Along with intramolecularly cyclized compound 2, novel π-extended dimeric product bis(1,2,3-triazole)-phenazinetetraone (4) was also generated in this reaction and isolated in charge-transfer complexes with perylene and coronene. The molecular structures of neutral 2, monoanionic 2−, and dianionic 22− were confirmed by single crystal X-ray structural analyses, where the acidic protons in 2 existed in the 2-position of the 1,2,3-triazole unit, whereas one proton in 2− was localized at the 1-position of the 1,2,3-triazole unit. The electron accepting ability of bis(1,2,3-triazole)-p-benzoquinone derivatives decreased in the order 2 ＞ 2− ＞ 22− due to electrostatic repulsive interactions in the anion radical and dianion state. Hydrogen-bonded new electron acceptor 4 was surrounded by four H2O molecules in the crystalline state, which formed an alternating donor–acceptor π-stacking interaction. [ABSTRACT FROM AUTHOR]

Abstract: Four ion-pair compounds that are based on the [Pd(mnt)2]− anion were synthesized and structurally characterized. Crystal structure determinations revealed that, in all four cases, the anions and cations stack as segregated columns, and that adjacent [Pd(mnt)2]− anions exhibit a strong tendency of dimerization within an anionic column. Values of χ m(T) in 2–350K indicated that these compounds are nearly diamagnetic. Results of the spin dimer analyses for the magnetic exchange interactions between the nearest-neighbor spins qualitatively illustrated the magnetic behaviors of these compounds. [Copyright &y& Elsevier]

Abstract: New supramolecular cation structures of (4-fluoroanilinium)([18]crown-6) and (4-methylanilinium)([18]crown-6) were introduced as counter cations to [Ni(dmit)2]− salts, which bear an S =1/2 spin, to form magnetic crystals. From the crystal structures and temperature dependent magnetic susceptibilities, both salts had isomorphous structure of one-dimensional arrangements of [Ni(dmit)2]− π-dimer along the b-axis. The magnetic ground state of these salts was spin singlet with the intradimer magnetic exchange energy of around −150K. [Copyright &y& Elsevier]

Abstract: Two compounds of composition [FBzPy][Pt(mnt)2] (1) and [FBzPy][Pt(mnt)2]·0.25-MeCN (2) ([FBzPy]+ =1-(4′-fluorobenzyl)pyridinium and mnt2− =maleonitriledithiolate) were prepared and their crystal structures were determined. The solvent molecule, MeCN, incorporated into lattice leads the anionic stacking pattern to be distinct between 1 and 2. The regular anionic stacking columns are connected by the anionic dimers to construct into 2D anionic networks in 1, while the anionic fourfold subunit develop into anionic layers though lateral S⋯S interactions in 2. As for two compounds, the magnetic susceptibilities in 2–350K were measured, and the magnetic exchange schemes were built based on the analyses both crystal structures and extended Hückel molecular orbital calculations. The magnetic coupling model of an alternating AFM Heisenberg chain with an isolated AFM coupling dimer was dealt with 1, while a spin dimer with s =1/2 with 2, and the magnetic coupling parameters were further gained via simulating the temperature dependent magnetic susceptibility data of two compounds. [Copyright &y& Elsevier]

Abstract: Two new H-bonding molecular magnets based on [Ni(mnt)2]− monoanion have been synthesized and characterized structurally. In crystal of 1, [Ni(mnt)2]− monoanions form the π-stacked sheets and the neighboring anionic sheets are held together via H-bonding interactions between –NH groups of diprotonated benzene-1,4-diamine and CN groups of mnt2− ligands. In crystal of 2, the neighboring anionic dimers form an anionic column via Ni…S contacting interactions, and these anionic stacks arrange into a sheet which is parallel to crystallographic ab-plane. The H-bonding interactions between diprotonated 1,4-diazabicyclo[2.2.2]octane cations and [Ni(mnt)2]− monoanions as well as between cations and solvent MeCN molecules stabilize the lattice. Magnetic susceptibility measurement for 1 indicates an activated magnetic behavior in the high-temperature range together with a Curie tail at the lower temperature range, but the magnetic feature deviates from the magnetic exchange model for a spin dimer with S =1/2. The magnetic nature of 2 reveals the presence of strongly antiferromagnetic interactions between the nearest-neighboring spins, the larger energy gap between spin ground and excited states results in a weakly paramagnetic property. [Copyright &y& Elsevier]