Alkaline Ion-Modulated Solid-State Supramolecular Organization in Mixed Organic/Metallorganic Compounds Based on 1,1′-Ethylenebis(4-aminopyridinium) Cations and Bis(oxamate)cuprate(II) Anions

Three new coordination compounds of formula (edap)₂­[Cu­(opba)]₂­·4H₂O (<b>1</b>), (edap)­[{Na₂(H₂O)₄}­{Cu₂(opba)₂}]­·2H₂O (<b>2</b>), and (edap)­[{K₂(H₂O)₂}­{Cu₂(opba)₂}]­·3H₂O (<b>3</b>) (edap = 1,1′-ethylenebis­(4-aminopyridinium) and opba = 1,2-phenylenebis­(oxamate)) were synthesized through the metathesis reaction involving A₂[Cu­(opba)] (A = Li⁺, Na⁺, and K⁺) and (edap)­Cl₂·2H₂O. Crystal structures of <b>1</b>–<b>3</b> and edap­(IO₃)₂­·4H₂O compound were elucidated by single crystal X-ray diffraction. Compounds <b>1</b>–<b>3</b> are built up from dinuclear copper­(II) entities, {[Cu­(opba)]₂}^4– with an asymmetric bis­(monatomic oxygen) bridge resulting from the parallel “out-of-plane” disposition of the planar mononuclear [Cu­(opba)]^2–. They possess distinct supramolecular arrangements of varying dimensionality (<i>n</i>D with <i>n</i> = 0 (<b>1</b>), 1 (<b>2</b>), and 2 (<b>3</b>)) in the solid state depending on the nature of the coordinated alkaline ion present alongside edap²⁺ counterions. While the {[Cu­(opba)]₂}^4– building blocks are well-isolated in <b>1</b>, they form either double chains or corrugated layers due to the coordination of the Na⁺ or K⁺ ions in <b>2</b> and <b>3</b>, respectively. Magnetic properties of <b>1</b>–<b>3</b> show a very weak antiferromagnetic coupling between the Cu^II ions through a double monatomic (μ-O) bridge (−<i>J</i> = 1.63(9) (<b>1</b>), 2.29(2) (<b>2</b>), and 1.65(3) cm^–1 (<b>3</b>)), the Hamiltonian being defined as <i><b>H</b></i> = −(<i><b>S</b></i>_{<i><b>1</b></i>}·<i><b>S</b></i>_{<i><b>2</b></i>}) + <i>g βH</i>(<i><b>S</b></i>_{<i><b>1</b></i>} + <i><b>S</b></i>_{<i><b>2</b></i>})

Solvent effects on the dimensionality of oxamato-bridged manganese(II) compounds

<p>Two new oxamate-containing manganese(II) complexes, [{Mn(H₂edpba)(H₂O)₂}₂]_n (<b>1</b>) and [Mn(H₂edpba)(dmso)₂]∙dmso∙CH₃COCH₃∙H₂O (<b>2</b>) (H₄edpba = <i>N,N′</i>-ethylenediphenylenebis(oxamic acid) and dmso = dimethylsulfoxide), have been synthesized and the structures of <b>1</b> and <b>2</b> were characterized by single crystal X-ray diffraction. The structure of <b>1</b> consists of neutral honeycomb networks in which each manganese(II) is six-coordinate by one H₂edpba²⁻ ligand and two carboxylate–oxygens from two other H₂edpba²⁻ ligands building the equatorial plane. Each manganese is connected to its nearest neighbor through two carboxylate(monoprotonated oxamate) bridges in an <i>anti</i>-<i>syn</i> conformation. A dmso solution of single crystals of <b>1</b> was placed under acetone atmosphere affording <b>2</b>, whereas putting <b>2</b> in equimolar water:ethanol mixture results in <b>1</b>. The molecular structure of <b>2</b> is made up of mononuclear manganese(II) units which are interlinked by weak C–H⋯π and edge-to-face π-stacking interactions leading to supramolecular chains along the crystallographic <i>b</i> axis. Magnetic measurements reveal the occurrence of an antiferromagnetic coupling between two manganese(II) ions through <i>anti-syn</i> carboxylate bridges for <b>1</b> [<i>J</i> = −1.18 cm⁻¹, the Hamiltonian being defined as <b><i>H</i> </b>= −<i>J</i> <b><i>S</i></b>₁^.<b><i>S</i></b>₂] and very weak intrachain ferromagnetic interactions in <b>2</b> [<i>J</i> = + 0.046 cm⁻¹, <b><i>H</i></b> = −<i>J</i> ∑_i<b><i>S</i></b>_i^.<b><i>S</i></b>_i + 1].</p