1394015-24-7Relevant academic research and scientific papers
Pillaring role of 4,4′-azobis(pyridine) in substituted malonate-containing manganese(II) complexes: Syntheses, crystal structures, and magnetic properties
Deniz, Mariadel,Hernandez-Rodriguez, Irene,Pasan, Jorge,Fabelo, Oscar,Canadillas-Delgado, Laura,Ruiz-Perez, Catalina,Yuste, Consuelo,Julve, Miguel,Lloret, Francesc
, p. 4505 - 4518,14 (2012)
Six new manganese(II) complexes of formulas [Mn2(Rmal) 2(H2O)2(azpy)]n (1-3), [Mn(Phmal)(H2O)(azpy)]n (4), [Mn2(Et 2mal)2(H2O)4(azpy)2] n (5), and [Mn(Bzmal)(H2O)3(azpy)] (6) [azpy = 4,4′-azobispyridine (1-6), Rmal = methylmalonate (Memal) (1), dimethylmalonate (Me2mal) (2), and butylmalonate (Butmal) (3), Phmal = phenylmalonate (4), Et2mal = diethylmalonate (5), and Bzmal = benzylmalonate (6)] were synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1-3 are three-dimensional compounds whose structure consists of corrugated layers of manganese(II) linked through syn-anti carboxylate (Rmal) bridges, which are pillared through the bis-monodentate azpy molecule. Complex 4 has a layered structure of manganese(II) ions connected by carboxylate (Phmal) bridges in the syn-anti coordination mode as in 1-3, the azpy group acting here as a terminally bound monodentate ligand. The structure of 5 consists of Et2mal-Mn(II) neutral chains linked through the azpy ligand, giving rise to a complex three-dimensional network. Complex 6 is constituted by neutral [Mn(Bzmal)(H 2O)3(azpy)] mononuclear units, which are interlinked through O-H???O, O-H???N, and π-π type intermolecular interactions to afford a three-dimensional supramolecular structure. The topological analysis of these crystallographic structures shows the occurrence of four different nets: a (3,4)-connected InS-type (1-3), a binodal layered hcb (4), a uninodal CdS-type (5), and a (4,5)-connected tcs topology (6). The magnetic properties of 1-5 were investigated in the 2.0-300 K temperature range. Overall antiferromagnetic behavior occurs in 1-4 with susceptibility maxima in the range 2.8-5.5 K, the exchange pathway being provided by the syn-anti carboxylate (substituted malonate) bridge [manganese-manganese separation in the range 5.4365(3)-5.5274(1) A]. Very weak antiferromagnetic interactions are observed in 5 through the trans-bis-monodentate Et2mal ligand, the intrachain manganese-manganese separation being 7.328(3) A. The much larger manganese-manganese separation through the bis-monodentate azpy ligand in 1-5 (values greater than 13.5 A) accounts for the lack of any significant magnetic interaction though this extended bridge.
