Pillaring role of 4,4′-azobis(pyridine) in substituted malonate-containing manganese(II) complexes: Syntheses, crystal structures, and magnetic properties

Six new manganese(II) complexes of formulas [Mn 2(Rmal) 2(H 2O) 2(azpy)] n (1-3), [Mn(Phmal)(H 2O)(azpy)] n (4), [Mn 2(Et 2mal) 2(H 2O) 4(azpy) 2] n (5), and [Mn(Bzmal)(H 2O) 3(azpy)] (6) [azpy = 4,4′-azobispyridine (1-6), Rmal = methylmalonate (Memal) (1), dimethylmalonate (Me 2mal) (2), and butylmalonate (Butmal) (3), Phmal = phenylmalonate (4), Et 2mal = 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 Et 2mal-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) Å]. Very weak antiferromagnetic interactions are observed in 5 through the trans-bis-monodentate Et 2mal ligand, the intrachain manganese-manganese separation being 7.328(3) Å. The much larger manganese-manganese separation through the bis-monodentate azpy ligand in 1-5 (values greater than 13.5 Å) accounts for the lack of any significant magnetic interaction though this extended bridge. © 2012 American Chemical Society.Financial support by the Spanish Ministerio de Ciencia e Innovación through projects MAT2010-16981, CTQ2010-15364, DPI2010-21103-C04-03, “Factoría de Crystalización” (Consolider Ingenio2010 CSD2006-0015), Molecular Nanoscience (Consolider Ingenio CSD2007-00010), ACIISI Gobierno de Canarias (PIL2070901), and Generalitat Valenciana (PROMETEO/2009/108, and ISIC/2012/002) is gratefully acknowledged. M. Déniz thanks the Spanish Ministerio de Ciencia e Innovación for a predoctoral fellowship.Peer Reviewe

Metal-organic coordination frameworks based on mixed methylmalonate and 4,4′-bipiridine ligands: synthesis, crystal structure and magnetic properties

Five new complexes of formulae [M2(4,4′-bpy)(Memal)2X2]n [M = Fe(III) (2), Mn(II) (3), Co(II) (4), Ni(II) (5) and Zn(II) (6), and X = Cl−/OH− (2) and H2O (3–6); 4,4′-bpy = 4,4′-bipyridine and Memal = methylmalonate dianion] have been synthesized by following the previously reported procedure for [Cu2(4,4′-bpy)(Memal)2(H2O)2]n (1). Moreover, two new phases of the Cu(II)/Memal/4,4′-bpy system, namely {[Cu(4,4′-bpy)2][Cu(4,4′-bpy)2(Memal)(NO3)(H2O)]}n·nNO3·3.5nH2O (7) and [Cu(4,4′-bpy)2(Memal)(H2O)]n·nH2O (8), were obtained by varying the synthetic conditions. They were all structurally characterized by single crystal X-ray diffraction, and the magnetic properties of 2–5, 7 and 8 were investigated in the temperature range 1.9–295 K. 1–6 are isomorphous compounds whose structure consists of square grids of metal ions linked through anti–syn carboxylate bridges that grow in the crystallographic ac plane. These layers are pillared along the b axis by bis-monodentate 4,4′-bpy ligands to afford a [4466]-sqp three-dimensional net. Ferro- (1 and 5) and antiferromagnetic (2–4) interactions between the metal ions are mediated by the carboxylate bridge in the anti–syn conformation, the bis-monodentate 4,4′-bpy ligand being unable to transmit a significant magnetic coupling. The values of the magnetic coupling (J) for 2–5 are −0.269(3), −0.225(2), −0.05 and +0.272(3) cm−1 respectively, the isotropic spin Hamiltonian being . Complexes 7 and 8 exhibit quite a different structure, as driven by the 4,4′-bpy groups. A square-grid of [Cu(4,4′-bpy)2]2n+n occurs in 7, which grows in the ab plane and is pillared through anti–syn carboxylate bridges from [Cu(Memal)(4,4′-bpy)2(NO3)(H2O)] units along the c axis to build up a [41263]-pcu net. Analysis of the magnetic data for this compound shows an overall antiferromagnetic behaviour with the coexistence of ferro- and antiferromagnetic interactions. The structure of 8 consists of linear chains of copper(II) running along the c axis, where aquabis(4,4′-bipyridine)copper(II) units are connected by bis(monodentate) methylmalonate ligands. A significant intrachain antiferromagnetic interaction is observed in 8 through the extended Cu–OCCCO–Cu exchange pathway [J = −1.38(1) cm−1]. The assembling role of the 4,4′-bpy coligand in 1–8 and in previous malonate-containing complexes is analyzed and discussed.Financial support from the Spanish Ministerio de Educación y Ciencia through projects MAT2007-60660, CTQ2007-61690 and ‘‘Factoría de Cristalización, Consolider-Ingenio2010’’ CSD2006-0015, the Generalitat Valenciana (Grupos 03/197) and Agencia Canaria de Investigación, Innovación y Sociedad de la Información PIL2070901 are gratefully acknowledged. M. D. acknowledges a predoctoral FPU-AP2007-02435 fellowship from the Ministerio de Ciencia e Innovación (MICINN). J. P. also thanks CSD2006-0015 for a postdoctoral contract.Peer Reviewe

Three new europium(III) methanetriacetate metal-organic frameworks: the influence of synthesis on the product topology

Three new metal-organic framework structures containing EuIII and the little explored methanetriacetate (C7H7O6 3-, mta 3-) ligand have been synthesized. Gel synthesis yields a two-dimensional framework with the formula [Eu(mta)(H2O)3] n ·2nH2O, (I), while two polymorphs of the three-dimensional framework material [Eu(mta)(H2O)] n ·nH2O, (II) and (III), are obtained through hydrothermal synthesis at either 423 or 443 K. Compounds (I) and (II) are isomorphous with previously reported GdIII compounds, but compound (III) constitutes a new phase. Compound (I) can be described in terms of dinuclear [Eu2(H2O)4]6+ units bonded through mta3- ligands to form a two-dimensional framework with topology corresponding to a (6,3)-connected binodal (4 3)(466683)-kgd net, where the dinuclear [Eu2(H2O)4]6+ units are considered as a single node. Compounds (II) and (III) have distinct three-dimensional topologies, namely a (41263)(4966)-nia net for (II) and a (41065)(41164)-K2O2; 36641 net for (III). The crystal density of (III) is greater than that of (II), consistent with the increase of temperature, and thereby autogeneous pressure, in the hydrothermal synthesis. © 2014 International Union of Crystallography.This work was partly funded through projects MAT2010-16981, MAT2011-27233-C02-02, DPI2010-2103-C04-03 and the Consolider-Ingenio projects CSD2007-00010, and CSD2006-00015 ‘La Factoría’ and CTQ2007-61690 from the Spanish MICINN, as well as through the Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI) through project PIL-2070901. JP acknowledges the Consolider CSD2006-00015 project for a post-doctoral contract.Peer Reviewe

Synthesis, structural analysis, and thermal and spectroscopic studies of methylmalonate-containing zinc(II) complexes

The synthesis, crystal structure, thermal analysis and spectroscopic studies of five zinc(II) complexes of formulae [Zn(Memal)(H2O)]n (1) and [Zn2(L)(Memal)2(H2O)2]n (2-5) [H2Memal = methylmalonic acid, and L = 4,4′-bipyridine (4,4′-bpy) (2), 1,2-bis(4-pyridyl)ethylene (bpe) (3), 1,2-bis(4-pyridyl)ethane (bpa) (4) and 4,4′-azobispyridine (azpy) (5)] are presented here. The crystal structure of 1 is a three-dimensional arrangement of zinc(II) cations interconnected by methylmalonate groups adopting the μ3-κ2O:κO’:κO”:κO”’ coordination mode to afford a rare (10,3)-d utp-network. The structures of the compounds 2-5 are also three-dimensional and they consist of corrugated square layers of methylmalonate-bridged zinc(II) ions which are pillared by bis-monodentate 4,4′-bpy (2), bpe (3), bpa (4) and azpy (5) ligands. The Memal ligand in 2-5 adopts the μ3-κO:κO′:κO′′:κO′′′ coordination mode. Each zinc(II) ion in 1-5 is six-coordinated with five (1)/four (2-5) methylmalonate-oxygen atoms, a water molecule (1-5) and a nitrogen atom from a L ligand (2-5) building distorted octahedral environments. The rod-like L co-ligands in 2-5 appear as useful tools to control the interlayer metal-metal separation, which covers the range 8.4311(5) Å (2) – 9.644(3) Å (5). The influence of the co-ligand on the fluorescence properties of this series of compounds has been analyzed and discussed by steady-state and time resolved spectroscopy on all five compounds in the solid state. © 2012 Académie des sciences. des sciences. Published by Elsevier Masson SAS. All rights reserved.Funding for this work provided by the Ministerio de Ciencia e Innovación through the projects MAT2010-16981, Consolider Ingenio2010–CSD2006-0015, DPI2010-21103-C04-03 and by the Agencia Canaria de Investigación, Innovación y Sociedad de la Información, Gobierno de Canarias through projects PIL2070901, SolSubC200801000088 and structuring NANOMAC is gratefully acknowledged. M.D. thanks the Spanish Ministerio de Educación y Cultura for a predoctoral fellowship.Peer Reviewe

Syntheses, crystal structures and magnetic properties of five new manganese(ii) complexes: Influence of the conformation of different alkyl/aryl substituted malonate ligands on the crystal packing

et al.Five new manganese(ii)-based complexes of general formula [Mn(Rmal)(H 2O)]n with Rmal = methylmalonate (Memal) (1), dimethylmalonate (Me2mal) (2), diethylmalonate (Et2mal) (3), butylmalonate (Butmal) (4) and benzylmalonate (Bzmal) (5) were synthesized and their structures characterized by single crystal X-ray diffraction. 1 and 2 are three-dimensional compounds whereas 3-5 exhibit two-dimensional networks. The structure of 1 consists of chains of μ-κO:κO bridged aquamanganese(ii) ions which are interlinked through anti-anti carboxylate bridges. The structure of 2 is built by double μ-κO:κO bridged bis[aquamanganese(ii)] entities which are linked to six other dimanganese(ii) units through oxo- and anti-syn carboxylate bridges. These dinuclear entities also occur in 4 and 5. They are interconnected by anti-anti and anti-syn carboxylate bridges to four other units, leading to neutral layered structures. Finally, compound 3 consists of aqua-bridged chains of manganese(ii) ions connected through tetrakis(monodentate) Et2mal ligands leading to a sheet-like structure. The topological representation of the crystal structures shows the of four different nets: (10,3)-d utp (1), 6-connected crs (2), gek2 (3) and the square-grid sql topology (4-5). The magnetic properties of 1-5 were investigated in the temperature range 2.0-300 K. Overall antiferromagnetic behavior occurs in 1, 2, 4 and 5 with susceptibility maxima in the range 3.6-17.0 K. Compound 3 exhibits an overall antiferromagnetic behaviour in the high temperature range with a weak spin canting in the low temperature domain and magnetic ordering below ca. 32 K. This journal is © 2014 The Royal Society of Chemistry.Financial support from the Spanish Ministerio de Ciencia e Innovación through projects MAT2010-16981, CTQ2010-15364, MAT2011-27233-C0-02, “Factoría de Cristalización” (Consolider Ingenio2010 CSD2006-0015), Gobierno de Canarias (PIL2070901) and Generalitat Valenciana (ISIC/2012/002) is gratefully acknowledged. M. Déniz and J. Pasán thank the Spanish Ministerio de Ciencia e Innovación for a predoctoral fellowship (M. D.) and the “Factoría de Cristalización” (Consolider Ingenio2010 CSD2006-0015) for a postdoctoral contract (J. P.).Peer Reviewe

Synthesis, structural analysis, and magnetic properties of ethylmalonate-manganese(II) complexes

12 páginas, 10 figuras, 6 tablas.-- et al.Five manganese(II) complexes of formulas [Mn2(Etmal)2(H2O)2(L)]n (1–4) and {[Mn(Etmal)2(H2O)][Mn(H2O)4]}n (5) with H2Etmal = ethylmalonic acid (1–5) and L = 1,2-bis(4-pyridyl)ethane (bpa) (1), 4,4′-azobispyridine (azpy) (2), 4,4′-bipyridyl (4,4′-bpy) (3), and 1,2-bis(4-pyridyl)ethylene (bpe) (4) were synthesized and structurally characterized by single crystal X-ray diffraction. Their thermal behavior and variable-temperature magnetic properties were also investigated. The structure of the compounds 1–4 consists of corrugated layers of aquamanganese(II) units with intralayer carboxylate-ethylmalonate bridges in the anti-syn (equatorial-equatorial) coordination mode which are linked through bis-monodentate bpa (1), azpy (2), 4,4′-bpy (3), and bpe (4) ligands to build up a three-dimensional (3D) framework. The structure of compound 5 is made up by zigzag chains of manganese(II) ions with a regular alternation of [Mn(H2O)4]2+ and chiral (either Δ or λ enantiomeric forms) [Mn(Etmal)2(H2O)]2– units within each chain. In contrast to the bidentate/bis-monodentate coordination mode of the Etmal ligand in 1–4, it adopts the bidentate/monodentate coordination mode in 5 with the bridging carboxylate-ethylmalonate also exhibiting the anti-syn conformation but connecting one equatorial and an axial position from adjacent metal centers. The manganese–manganese separation through the carboxylate-ethylmalonate bridge in 1–5 vary in the range 5.3167(4)–5.5336(7) Å. These values are much shorter than those across the extended bis-monodentate N-donors in 1–4 with longest/shortest values of 11.682(3) (3)/13.9745(9) Å (4). Compounds 1–5 exhibit an overall antiferromagnetic behavior, where the exchange pathway is provided by the carboxylate-ethylmalonate bridge. Monte Carlo simulations based on the classical spin approach (1–5) were used to successfully reproduce the magnetic data of 1–5.Financial support by the Spanish Ministerio de Ciencia e Innovación through projects MAT2007-60660, MAT2010-16981, CTQ2010-15364, DPI2010-21103-C04-03, “Factoría de Crystalización” (Consolider Ingenio2010 CSD2006-0015), Molecular Nanoscience (Consolider Ingenio CSD2007-00010), ACIISI Gobierno de Canarias and Generalitat Valenciana (PROMETEO/2009/108) is gratefully acknowledged. M.D. and J.F.-S. thank the Spanish Ministerio de Ciencia e Innovación (M.D.) and the Generalitat Valenciana (J.F.-S.) for predoctoral fellowships. J.P. also thanks the Proyecto Estructurante NANOMAC (ACIISI-Gobierno de Canarias) for a postdoctoral contract.Peer reviewe