New Family of Six Stable Metals with a Nearly Isotropic Triangular Lattice of Organic Radical Cations and Diluted Paramagnetic System of Anions: κ(κ_⊥)‑(BDH-TTP)₄MX₄·Solv, where M = Co^II, Mn^II; X = Cl, Br, and Solv = (H₂O)₅, (CH₂X₂)

A new family of six paramagnetic metals, namely, κ-(BDH-TTP)₄­CoCl₄­·(H₂O)₅ (<b>I</b>), κ-(BDH-TTP)₄­Co_0.54Mn_0.46Cl₄­·(H₂O)₅ (<b>II</b>), κ-(BDH-TTP)₄­MnCl₄­·(H₂O)₅ (<b>III</b>), κ_⊥-(BDH-TTP)₄­CoBr₄­·(CH₂Cl₂) (<b>IV</b>), κ_⊥-(BDH-TTP)₄­MnBr₄­·(CH₂Cl₂) (<b>V</b>), and κ_⊥-(BDH-TTP)₄­MnBr₄­·(CH₂Br₂) (<b>VI</b>), has been synthesized and characterized by X-ray crystallography, four-probe conductivity measurements, SQUID magnetometry, and calculations of electronic structure. The newly discovered κ_⊥-type packing motif of organic layers differs from the parent κ-type by a series of longitudinal shifts of BDH-TTP radical cations in the crystal structure. Salts <b>I</b>–<b>VI</b> form two isostructural groups: <b>I</b>–<b>III</b> (κ) and <b>IV</b>–<b>VI</b> (κ_⊥). Salts <b>I</b>–<b>III</b> are isostructural to the previously discovered κ-(BDH-TTP)₂­Fe^IIIX₄ (X = Cl, Br) even though the charge of FeX₄^– anions is half that of the MX₄^2– (M = Co, Mn) anions. The tetrahedral anions are disordered in <b>I</b>–<b>III</b> but completely ordered in <b>IV</b>–<b>VI</b>. The type of included solvent molecule is solely determined by the anion size. The paramagnetic subsystem is effectively spin diluted either by anion disorder (<b>I</b>–<b>III</b>) or by spatial separation (<b>IV</b>–<b>VI</b>). The Weiss constants are virtually zero for all compounds (e.g., θ­(<b>III</b>) = 0.0056 K, θ­(<b>V</b>) = −0.076 K). Curie constants are dominated by anion paramagnetic centers indicating high spin states 5/2 for Mn^II and 3/2 for Co^II with large spin–orbital coupling. All compounds retain metallic properties down to 4.2 K. There is a magnetic breakdown gap of width (<i>w</i>) in the chiral salts <b>IV</b>–<b>VI</b>: <i>w</i>(<b>IV</b>) > <i>w</i>(<b>V</b>) ≈ <i>w</i>(<b>VI</b>) but no gap in the centrosymmetric salts <b>I</b>–<b>III</b>. Electronic structure calculations at room temperature revealed a nearly isotropic triangular lattice in <b>I</b>–<b>III</b> and a honeycomb lattice in <b>IV</b>–<b>VI</b> with an extreme geometric spin frustration exceeding the level reported for the quantum “spin liquid” κ-(BEDT-TTF)₂­Cu₂(CN)₃

A Series of Two Oxidation Reactions of <i>ortho</i>-Alkenylbenzamide with Hypervalent Iodine(III): A Concise Entry into (3<i>R</i>,4<i>R</i>)‑4-Hydroxymellein and (3<i>R</i>,4<i>R</i>)‑4-Hydroxy-6-methoxymellein

A sequence of oxidation reactions of alkenamides with hypervalent iodine is described. Oxidation of <i>ortho</i>-alkenylbenzamide substrates selectively gave isochroman-1-imine products. The products underwent further oxidation in the presence of a Pd salt catalyst leading to regioselective C–H acetoxylation at the 8-position. A series of oxidations was applied to the crucial steps of asymmetric synthesis of 4-hydroxymellein derivatives

A Series of Two Oxidation Reactions of <i>ortho</i>-Alkenylbenzamide with Hypervalent Iodine(III): A Concise Entry into (3<i>R</i>,4<i>R</i>)‑4-Hydroxymellein and (3<i>R</i>,4<i>R</i>)‑4-Hydroxy-6-methoxymellein

A sequence of oxidation reactions of alkenamides with hypervalent iodine is described. Oxidation of <i>ortho</i>-alkenylbenzamide substrates selectively gave isochroman-1-imine products. The products underwent further oxidation in the presence of a Pd salt catalyst leading to regioselective C–H acetoxylation at the 8-position. A series of oxidations was applied to the crucial steps of asymmetric synthesis of 4-hydroxymellein derivatives

Role of the Anion Layer’s Polarity in Organic Conductors β″-(BEDT-TTF)₂XC₂H₄SO₃ (X = Cl and Br)

A two-dimensional (2D) organic conductor β″-(BEDT-TTF)2ClC2H4SO3 (1) crystallized in the P21/m and has a polar anion located on the mirror plane, parallel to the 2D BEDT-TTF conducting layer. A temperature-induced phase transition tilts the anion such that a component of its electric dipole becomes perpendicular to the conducting plane. This low-temperature phase β″-β′′-(BEDT-TTF)2ClC2H4SO3 (1L) has two crystallographically independent donor layers, A and B, each of which is bordered by the positive or negative side of the anion’s dipole (← B → A ← B → A ←). This exposes each donor layer to different effective electric fields and leads to layers of A and B with dissimilar oxidation states. Consequently, the transition can be called the temperature-induced non-doped-to-doped transition. The low-temperature phase (1L) is isomorphous with β″-β′′-(BEDT-TTF)2BrC2H4SO3 (2) from room temperature to at least 100 K, suggesting that 2 is also doped and it shows a very broad MI transition at 70 K. Applying only 2 kbar of static pressure sharpens the MI transition, indicating that the tilted anion straightens, and therefore, we suggest that it can be termed a pressure-induced doped-to-non-doped transition

Uniaxial Strain Orientation Dependence of Superconducting Transition Temperature (<i>T</i>_c) and Critical Superconducting Pressure (<i>P</i>_c) in β-(BDA-TTP)₂I₃

Dependence of the superconducting transition temperature (<i>T</i>_c) and critial superconducting pressure (<i>P</i>_c) of the pressure-induced superconductor β-(BDA-TTP)₂I₃ [BDA-TTP = 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] on the orientation of uniaxial strain has been investigated. On the basis of the overlap between the upper and lower bands in the energy dispersion curve, the pressure orientation is thought to change the half-filled band to the quarter-filled one. The observed variations in <i>T</i>_c and <i>P</i>_c are explained by considering the degree of application of the pressure and the degree of contribution of the effective electronic correlation at uniaxial strains with different orientations parallel to the conducting donor layer