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The title compound, [Co(C5H7O2)2(C6H12N2)]n, was obtained as a one-dimensional coordination polymer from bis(acetylacetonato)diaquacobalt(II), [Co(acac)2(OH2)2], and 1,4-diazabicyclo[2.2.2]octane (DABCO), a diamine with good bridging ability and rod-like spacer function. In the chain complex that extends along the c axis, the CoII atom is six-coordinated, the O-donor atoms of the chelating acac ligands occupying the equatorial positions and the bridging DABCO ligands being in trans-axial positions. In the crystal structure, the DABCO ligand is conformationally disordered in a 50:50 manner as a result of its location across a crystallographic mirror plane. The metal–metal distance is very close to that in a related compound exhibiting weak antiferromagnetic exchange between the CoII ions, and the title compound can thus be useful for obtaining more information about the contribution of different bridges to the magnetic coupling between paramagnetic ions.

LiKCuP 2 O 7 compounds were obtained by high temperature solid phase method. The crystal structure, thermal behavior, infrared spectroscopy, and magnetic behavior are discussed. [Display omitted] • The 3D framework of LiKCuP 2 O 7 consists of [CuP 2 O 7 ]2- layers, with Li+ and K+ cations filling between the layers. • Magnetic susceptibility measurements over a wide temperature range suggest that the compound is antiferromagnetic. • The structure comparison of the A–Cu–P–O system and the effect of cation size on its structures have been discussed. By the application of cation substitution with a site in A–Cu–P–O (A = alkali or mixed-alkali metals) system, a mixed-alkaline metal copper-containing phosphate LiKCuP 2 O 7 has been obtained. Single crystal X-ray diffraction analysis shows that LiKCuP 2 O 7 belongs to the P 2 1 / c space group and features a three-dimensional (3D) network constructed by LiO 4 , KO 9 , CuO 5 , P 2 O 7 units. Interestingly, the CuO 5 polyhedra are interlinked with P 2 O 7 units via vertex-sharing O atoms to form two-dimensional (2D) layers, where the Li+, K+ cations reside. In order to understanding the influence of cation size on the 3D networks as well as different dimensions of Cu–P–O frameworks, the structure comparisons in the A–Cu–P–O system have been discussed in detailed. Thermal behavior and infrared spectroscopy have been analysed. What is more, magnetic susceptibility measurements over a wide range of temperature exhibit the presence of antiferromagnetic behaviour. [ABSTRACT FROM AUTHOR]

Spin crossover compounds are a diverse class of switchable materials with applications ranging from data storage devices to sensors. Iron(III) spin crossover complexes have received renewed attention over the last 10 years with an increasing number of abrupt and hysteretic spin crossover systems discovered. This review provides a detailed overview of this exciting and increasingly interdisciplinary area of research with a particular focus on the structures of these materials and how this impacts their magnetic performance. [ABSTRACT FROM AUTHOR]

The title compound, [Co(C5H7O2)2 (C6H12N2)]n, was obtained as a one-dimensional coordination polymer from bis(acetylacetonato)di-aquacobalt(II), [Co(acac)2 (OH2)2], and 1,4-diaza-bicyclo[2.2.2]octane (DABCO), a diamine with good bridging ability and rod-like spacer function. In the chain complex that extends along the c axis, the CoII atom is six-coordinated, the O-donor atoms of the chelating acac ligands occupying the equatorial positions and the bridging DABCO ligands being in trans-axial positions. In the crystal structure, the DABCO ligand is conformationally disordered in a 50:50 manner as a result of its location across a crystallographic mirror plane. The metal-metal distance is very close to that in a related compound exhibiting weak antiferromagnetic exchange between the CoII ions, and the title compound can thus be useful for obtaining more information about the contribution of different bridges to the magnetic coupling between paramagnetic ions. [ABSTRACT FROM AUTHOR]

The title compound, [Co(C5H7O2)2 (C6H12N2)]n, was obtained as a one-dimensional coordination polymer from bis(acetylacetonato)di-aquacobalt(II), [Co(acac)2 (OH2)2], and 1,4-diaza-bicyclo[2.2.2]octane (DABCO), a diamine with good bridging ability and rod-like spacer function. In the chain complex that extends along the c axis, the CoII atom is six-coordinated, the O-donor atoms of the chelating acac ligands occupying the equatorial positions and the bridging DABCO ligands being in trans-axial positions. In the crystal structure, the DABCO ligand is conformationally disordered in a 50:50 manner as a result of its location across a crystallographic mirror plane. The metal-metal distance is very close to that in a related compound exhibiting weak antiferromagnetic exchange between the CoII ions, and the title compound can thus be useful for obtaining more information about the contribution of different bridges to the magnetic coupling between paramagnetic ions. [ABSTRACT FROM AUTHOR]

Abstract: We describe the preparation, crystal structure determination, magnetic and transport properties of two novel Mn-containing perovskites, with a different electronic configuration for Mn atoms located in B site. Ca3Mn3+ 2WO9 and Ca3Mn3+/4+ 2NbO9 were synthesized by standard ceramic procedures; the crystallographic structure was studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD). Both phases exhibit a monoclinic symmetry (S.G.: P21/n); Ca3Mn2WO9 presents a long-range ordering over the B sites, whereas Ca3Mn2NbO9 is strongly disordered. By “in-situ” NPD, the temperature evolution of the structure study presents an interesting evolution in the octahedral size (〈Mn–O〉) for Ca3Mn2NbO9, driven by a charge ordering effect between Mn3+ and Mn4+ atoms, related to the anomaly observed in the transport measurements at T≈160K. Both materials present a magnetic order below T C =30K and 40K for W and Nb materials, respectively. The magneto-transport measurements display non-negligible magnetoresistance properties in the paramagnetic regime. [Copyright &y& Elsevier]

Abstract: The synthesis, X-ray structure and magnetic properties of two new zoledronato complexes are presented: Mn(II)(H3Zol)2(H2O)2, (I) and Fe(III)15(HZol)10(H2Zol)2 (H2O)24 (2/3Cl:1/3H2O)6·7Cl·65(H2O) (II), where H4Zol=zoledronic acid=C5H10N2O7P2. Complex (I) is a dimer, built up around an inversion centre where the cation is located, surrounded by two chelating zoledronate anions and two water molecules. The structure is isomorphous to the Co, Ni and Zn isologues. A quite different structure is the Fe(III) complex which consists of a centrosymmetric cluster with 15 Fe(III) cations (one of them at the inversion centre), 12 zoledronate anions, in different protonation states and 26 coordinated water molecules, 24 of which show full occupancy and the remaining 2 share 6 coordination sites with 4 chlorine anions. There are in addition 7 chlorine counterions and a not well determined number of hydration water molecules, their number being adjusted as to match the chemical and TGA analysis. The general shape of the molecule is that of a 6 arm propeller with a Fe(III) cation at its center and two FeO6 coordination polyhedra sitting above and below, defining some sort of “paddle wheel axis”, perpendicular to the wheel plane. Around this axis there is an almost perfect circular structure formed by other six FeO6 octahedra, to which the “paddles”, defined by the remaining six FeO6 groups attach. The ensemble presents some unusual (Fe···OPO) n loops (n =2,3,4), some of them unreported, and displays a striking non-crystallographic −3 symmetry. The protonation state of the zoledronato ligands were inferred from the counterions effectively found and charge balance considerations. Both compounds present a paramagnetic behaviour at R.T, and obey a Curie Weiss law down to rather low temperatures (15K for (I), 100(K) for (II)) with a tendency to different types of interactions viz., ferromagnetic for (I) and antiferromagnetic for (II). The geometry of the F15 cluster is analyzed. [Copyright &y& Elsevier]

A new iron(II) coordination polymer, [FeCl(NCH)(NCH)], has been synthesized under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction. This material crystallizes in the monoclinic space group C2/c, with a = 11.2850(6), b = 13.8925(7), c = 17.0988(9) Å and β = 94.300(3)º ( Z = 4). The crystal structure consists of neutral zig-zag chains, in which the iron(II) ions are octahedrally coordinated. The infinite polymer chains are packed into a three-dimensional structure through C-H···Cl interactions. Magnetic susceptibility measurements reveal the existence of weak antiferromagnetic interactions between the iron(II) ions. The effective magnetic moment, μ = 5.33 μ, is consistent with a high-spin iron(II) configuration. Graphical Abstract: The crystal structure of the coordination polymer [FeCl(NCH)(NCH)] consists of neutral zig-zag chains, in which the iron(II) ions are octahedrally coordinated.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the crystal structure, magnetic and electrical transport properties of the new ternary compound Eu20Ni42As31, crystallizing in the hexagonal Sm20Ni42P31 structure type, space group P63/m, a =21.1496(7), c =4.0734(2)Å, according to X-ray powder diffraction. From magnetic investigations it is evidenced that in this compound the europium is divalent, Eu2+. The compound orders antiferromagnetically at a Neèl temperature T N =5K. However, in moderate magnetic fields an overall ferromagnetic-like magnetization is observed. The measurements of the electrical resistivity prove this magnetic behaviour as well as the metallic character of the compound Eu20Ni42As31. [Copyright &y& Elsevier]

Abstract: The monoanionic Ni, Au and Cu bisdithiolene complexes based on the 1-(pyridin-4-yl)-ethylene-1,2-dithiolate were prepared and isolated as [PPh4]+, [n-Bu4N]+ and [Na(18C6)]+ salts which were characterised by single-crystal X-ray diffraction, cyclic voltammetry, EPR and magnetic susceptibility measurements. All the complexes adopt a square planar coordination geometry with a trans arrangement of the substituent pyridine rings whose planes are rotated from 13° to 33° relatively to the central MS4 core. The C–C and C–S bond lengths are consistent with ene-1,2-dithiolate form of the ligand and MIII oxidation state. The Ni complexes are paramagnetic with an effective magnetic moment of ∼1.7BM. [Copyright &y& Elsevier]

Abstract: A manganese(II) complex with N,N′-bis(carboxymethyl)dithiooxamide (H4GLYDTO), [Mn(H2GLYDTO)(H2O)2] n , has been synthesized and characterized by elemental analysis and thermogravimetric analysis, as well as by infrared, electronic and EPR spectroscopy and magnetic susceptibility measurements. The crystal and molecular structure of this complex was determined by single-crystal X-ray structure analysis. The compound shows a 3D porous framework with alternate left- and right-handed helical channels where the manganese(II) ions have an octahedral environment. Variable temperature magnetic measurements reveal the existence of very weak antiferromagnetic interactions through the syn-anti carboxylate bridge, with an exchange parameter of J/k =−0.12K. [Copyright &y& Elsevier]

Abstract: The ternary rare-earth nickel arsenides R6Ni15As10 (R=Y, Sm, Gd, Tb, Dy) were synthesized from the elements by reaction at elevated temperatures. They were found to crystallize with a hexagonal structure which was determined from single-crystal X-ray data in case of Tb6Ni15As10, space group P63/m, Z =2, a =17.005(1)Å and c =3.8877(2)Å. The crystal structure for the isostructural compound Gd6Ni15As10 has been determined using X-ray powder diffraction data (full profile refinement: a =17.0350(4)Å and c =3.9183(1)Å). These compounds belong to a large family of hexagonal structures with a metal to metalloid ratio of 2:1. The paramagnetism of these compounds is only due to the lanthanoid 4f magnetic moment, whereas nickel is non-magnetic. At low temperatures the samples undergo magnetic transitions, anti-ferromagnetic in case of the Sm and Gd ternaries with T N =15 and 24K and ferromagnetic for Tb6Ni15As10 with T C =12K, respectively. The temperature dependence of the electrical resistivity, ρ(T), reflects the metallic character of these compounds. Characteristic changes of the slopes of the ρ(T) plots confirm the magnetic transitions. [Copyright &y& Elsevier]