Directed <i>Ortho</i>-Lithiation of Aminophosphazenes: An Efficient Route to the Stereoselective Synthesis of <i>P</i>‑Chiral Compounds

<i>Ortho</i>-directed lithiation of <i>P</i>,<i>P</i>-diphenylaminophosphazenes followed by electrophilic quench is described as an efficient process for synthesizing <i>P</i>-chiral <i>ortho</i>-functionalized derivatives in high yields and diastereoselectivities. The method allows the tunable preparation of structurally diverse enantiopure <i>P</i>-chiral compounds including phosphinic and phosphinothioic amides, phosphinic esters, phosphine oxides, and <i>o</i>-aminophosphines

Series of Metal Organic Frameworks Assembled from Ln(III), Na(I), and Chiral Flexible-Achiral Rigid Dicarboxylates Exhibiting Tunable UV–vis–IR Light Emission

Two series of isoreticular chiral metal–organic frameworks assembled from Ln­(III) (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), Na­(I), and chiral flexible-achiral rigid dicarboxylate ligands, formulated as [NaLn­(Tart)­(BDC)­(H₂O)₂] (<b>S1</b>) and [NaLn­(Tart)­(biBDC)­(H₂O)₂] (<b>S2</b>) (H₂Tart = tartaric acid; H₂BDC = terephthalic acid; H₂biBDC = biphenyl-4,4′-dicarboxylic acid), were obtained as single phases under hydrothermal conditions. The compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning electron microscopy (SEM-EDX), elemental analysis, and X-ray thermodiffractometry. The catalytic activity has been also investigated. The photoluminescence properties of selected compounds have been investigated, exhibiting room temperature tunable UV–vis–IR light emission

Series of Metal Organic Frameworks Assembled from Ln(III), Na(I), and Chiral Flexible-Achiral Rigid Dicarboxylates Exhibiting Tunable UV–vis–IR Light Emission

Two series of isoreticular chiral metal–organic frameworks assembled from Ln­(III) (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), Na­(I), and chiral flexible-achiral rigid dicarboxylate ligands, formulated as [NaLn­(Tart)­(BDC)­(H₂O)₂] (<b>S1</b>) and [NaLn­(Tart)­(biBDC)­(H₂O)₂] (<b>S2</b>) (H₂Tart = tartaric acid; H₂BDC = terephthalic acid; H₂biBDC = biphenyl-4,4′-dicarboxylic acid), were obtained as single phases under hydrothermal conditions. The compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning electron microscopy (SEM-EDX), elemental analysis, and X-ray thermodiffractometry. The catalytic activity has been also investigated. The photoluminescence properties of selected compounds have been investigated, exhibiting room temperature tunable UV–vis–IR light emission

Antisymmetric Exchange in Triangular Tricopper(II) Complexes: Correlation among Structural, Magnetic, and Electron Paramagnetic Resonance Parameters

Two new trinuclear copper­(II) complexes, [Cu₃(μ₃-OH)­(daat)­(Hdat)₂(ClO₄)₂(H₂O)₃]­(ClO₄)₂·2H₂O (<b>1</b>) and [Cu₃(μ₃-OH)­(aaat)₃(H₂O)₃]­(ClO₄)₂·3H₂O (<b>2</b>) (daat = 3,5-diacetylamino-1,2,4-triazolate, Hdat = 3,5-diamino-1,2,4-triazole, and aaat = 3-acetylamino-5-amino-1,2,4-triazolate), have been prepared from 1,2,4-triazole derivatives and structurally characterized by X-ray crystallography. The structures of <b>1</b> and <b>2</b> consist of cationic trinuclear copper­(II) complexes with a Cu₃OH core held by three <i>N</i>,<i>N</i>-triazole bridges between each pair of copper­(II) atoms. The copper atoms are five-coordinate with distorted square-pyramidal geometries. The magnetic properties of <b>1</b> and <b>2</b> and those of five other related 1,2,4-triazolato tricopper­(II) complexes with the same triangular structure (<b>3–7</b>) (whose crystal structures were already reported) have been investigated in the temperature range of 1.9–300 K. The formulas of <b>3–7</b> are [Cu₃(μ₃-OH)­(aaat)₃(H₂O)₃]­(NO₃)₂·H₂O (<b>3</b>), {[Cu₃(μ₃-OH)­(aat)₃(μ₃-SO₄)]·6H₂O}_<i>n</i> (<b>4</b>), and [Cu₃(μ₃-OH)­(aat)₃A­(H₂O)₂]­A·<i>x</i>H₂O [A = NO₃^– (<b>5</b>), CF₃SO₃^– (<b>6</b>), or ClO₄^– (<b>7</b>); <i>x</i> = 0 or 2] (aat =3-acetylamino-1,2,4-triazolate). The magnetic and electron paramagnetic resonance (EPR) data have been analyzed by using the following isotropic and antisymmetric exchange Hamiltonian: <i>H</i> = –<i>J</i>[<i>S</i>₁<i>S</i>₂ + <i>S</i>₂<i>S</i>₃] – <i>j</i>[<i>S</i>₁<i>S</i>₃] + <i>G</i>[<i>S</i>₁ × <i>S</i>₂ + <i>S</i>₂ × <i>S</i>₃ + <i>S</i>₁ × <i>S</i>₃]. <b>1</b>–<b>7</b> exhibit strong antiferromagnetic coupling (values for both –<i>J</i> and –<i>j</i> in the range of 210–142 cm^–1) and antisymmetric exchange (<i>G</i> varying from to 27 to 36 cm^–1). At low temperatures, their EPR spectra display high-field (<i>g</i> < 2.0) signals indicating that the triangles present symmetry lower than equilateral and that the antisymmetric exchange is operative. A magneto-structural study showing a lineal correlation between the Cu–O–Cu angle of the Cu₃OH core and the isotropic exchange parameters (<i>J</i> and <i>j</i>) has been conducted. Moreover, a model based on Moriya’s theory that allows the prediction of the occurrence of antisymmetric exchange in the tricopper­(II) triangles, via analysis of the overlap between the ground and excited states of the local Cu­(II) ions, has been proposed. In addition, analytical expressions for evaluating both the isotropic and antisymmetric exchange parameters from the experimental magnetic susceptibility data of triangular complexes with local spins (<i>S</i>) of ¹/₂, ³/₂, or ⁵/₂ have been purposely derived. Finally, the magnetic and EPR results of this work are discussed and compared with those of other tricopper­(II) triangles reported in the literature

Phyllanthus emblica

The experimentally observed stereomutation of spiro-1,2-oxaphosphetanes is shown by DFT calculations to proceed through successive M_B2 or M_B4 and M_B3 mechanisms involving two, four, and three Berry pseudorotations at phosphorus, respectively. Oxaphosphetane decomposition takes place in a single step via a polar transition state. The calculated activation parameters for this reaction are in good agreement with those determined experimentally

A Binuclear Mn^III Complex of a Scorpiand-Like Ligand Displaying a Single Unsupported Mn^III–O–Mn^III Bridge

The crystal structure of a binuclear Mn^III complex of a scorpiand-like ligand (<b>L</b>) displays an unsupported single oxo bridging ligand with a Mn^III–O–Mn^III angle of 174.7°. Magnetic susceptibility measurements indicate strong antiferromagnetic coupling between the two metal centers. DFT calculations have been carried out to understand the magnetic behavior and to analyze the nature of the observed Jahn–Teller distortion. Paramagnetic ¹H NMR has been applied to rationalize the formation and magnetic features of the complexes formed in solution