Study of the Two-Dimensional [MM‘(C₃H₂O₄)₂(H₂O)₄] (M = Ba, Sr and M‘ = Cu, Mn) Systems:  Synthesis, Structure, Magnetic Properties, and Thermal Decomposition

Abstract

Compounds with the general formula [MM‘(C3H2O4)2(H2O)4] (M = Ba, Sr; M‘ = Cu, Mn; C3H2O4 = malonate) have been synthesized and characterized. Single-crystal X-ray diffraction study on the [SrCu(C3H2O4)2(H2O)4] compound indicates that it crystallizes in the orthorhombic space group, Pccn, Z = 4, with unit cell parameters a = 6.719(2), b = 18.513(7), and c = 9.266(4) Å. The structure consists of distorted octahedral copper(II) species which are extended along the ac plane forming a two-dimensional structure. The geometry of the alkaline-earth ions resembles a distorted antiprism. The other compounds are isostructural. The EPR spectra of the [MCu(C3H2O4)2(H2O)4] (M = Ba, Sr) compounds show an orthorhombic g tensor as consequence of a linear combination of the axial symmetry and the exchange interactions between magnetically different centers, but crystallographically equivalent. For the manganese compounds, the EPR spectra of polycrystalline samples show that the intensity of the signal increases with decreasing temperature down to 20 K, and at lower temperatures the intensity decreases, becoming silent below 7 K. Magnetic measurements show two-dimensional (2D) ferromagnetic and antiferromagnetic interactions for the copper and manganese phases, respectively. In all cases, the susceptibility data were fitted by the expression for a Heisenberg square-planar system. The obtained J/k values are 1.44 and 1.15 K, for the SrCu and BaCu compounds, respectively, and −0.65 and −0.59 K for the SrMn and BaMn compounds, respectively. For the manganese compounds, magnetic measurements show a magnetic ordering below 5 K which confirms the presence of a weak ferromagnetism. Thermal analyses of the phases show three different decomposition steps: dehydration, ligand pyrolysis, and evolution of the inorganic residue for all compounds. Taking these results into account, we performed further thermal treatments to obtain mixed oxides. These were obtained at short reaction times and at temperatures lower than those of the conventional ceramic method.

The Use of Malonate Coordination Polymers with CuII and BaII Atoms for Barium Cuprate Preparation

“…[20] However, the use of a fragment with unsubstituted malonate anions {Cu(mal) 2 } 2-(H 2 mal = malonic acid) as a building block under similar conditions did not allow the assembly of high-dimensional structures. [21] It can be assumed that the variation of the substituents of the malonic acid dianion would allow the control of the crystalline architecture of the polymeric molecules with barium ions, which certainly opens up new ways to the directed synthesis of coordination polymers suitable for the synthesis of barium cuprate by the mild thermolysis of precursor molecules.…”

Structural, Spectroscopic, Magnetic and Thermal Properties in the [SrM(C3H2O4)2(H2O)5]· 2 H2O (M = Mn, Fe, Co, Ni) System: Precursors of SrMO3–x Mixed Oxides

“…[6] In the case of the cobalt oxides, the Recently, a series of metal malonate complexes has been named cobaltites have attracted special attention due to reported. [13] In this paper, the synthesis and characteristheir application as low-cost fuel-cell electrodes. [7] ation of the [SrM(C 3 (4) O(2)ϪC(1) 1.249 (7) nation are summarized in Table 1.…”

“…The OϪCoϪO angles are close to 90°, in good agreement with those observed for other related compounds. [13] [14] The cobalt atom is raised by 0.016(1) Å above the square plane in the direction of O(2w). The distortion around the cobalt(II) ion has been calculated by quantification of the Muetterties and Guggenberger description.…”

Layered [BaM(C3H2O4)2(H2O)4] (M = Fe or Co) Complexes − Spectroscopic, Magnetic and Thermal Study

“…[1] It is a useful tool for connecting different metal ions and transmitting different magnetic interactions. In this way, ferromagnetically [2] or antiferromagnetically [3] coupled dimers, alternating chains, [4,5] polymeric trinuclear antiferromagnetic complexes [6,7] and two-dimensional ferromagnetic and antiferromagnetic compounds [8,9] have been obtained and studied.…”

“…4 ]. [8] In this paper we describe the synthesis and the spectroscopic and magnetic properties of the [BaM(C 3 H 2 O 4 ) 2 (H 2 O) 4 ] (M ϭ Fe or Co) compounds, together with their thermal study. These complexes will be abbreviated as BaFe and BaCo.…”