Assembly of [Mn^II₂Mn^III₂] <i>S</i> = 9 Clusters via Azido Bridges: a New Single-Chain Magnet

In the present work, we report a new manganese single-chain magnet built from tetranuclear MnII2MnIII2 mixed-valence units linked by end-on azido and oximato bridges. All of the intra- and intercluster interactions involve end-on azido bridges, resulting in one ferromagnetic chain of ferromagnetic clusters with local ground state S = 9

Assembly of [Mn^II₂Mn^III₂] <i>S</i> = 9 Clusters via Azido Bridges: a New Single-Chain Magnet

In the present work, we report a new manganese single-chain magnet built from tetranuclear MnII2MnIII2 mixed-valence units linked by end-on azido and oximato bridges. All of the intra- and intercluster interactions involve end-on azido bridges, resulting in one ferromagnetic chain of ferromagnetic clusters with local ground state S = 9

New Topology in Azide-Bridged Cobalt(II) Complexes: the Weak Ferromagnet [Co₂(N₃)₄(Hexamethylenetetramine)(H₂O)]_<i>n</i>

A new polynuclear azido-bridged Co(II) compound with formula [Co2(N3)4(HMTA)(H2O)]n (1) (HMTA = hexamethylenetetramine) has been structurally and magnetically characterized. The compound 1 crystallizes in the monoclinic system C2/m space group, and consist of a complex three-dimensional system in which end-to-end and end-on azido bridging ligands between the Co(II) atoms coexist. The HMTA ligand is also linking three different Co(II) atoms. The network analysis shows for 1 a three- and six-connected network topology not previously reported. The magnetic properties of 1 are also reported, and it was found that the magnetic interactions define another new three- and four-connected net assigned as a (6.82)(64.102)-tfo net. In the high temperature region the χM versus T plot can be fitted by using the Curie−Weiss law, and the best fit theta value is −26.6 K. For 1 magnetic ordering and spontaneous magnetization is achieved below Tc = 15.6 K

1D and 2D End-to-End Azide-Bridged Cobalt(II) Complexes: Syntheses, Crystal Structures, and Magnetic Properties

Two new polynuclear azido-bridged Co(II) compounds with formulas catena-[Co(μ1,3-N3)(N3)(py)2(H2O)]n (1) and [Co(μ1,3-N3)2(4-acpy)2]n (2) (py = pyridine, 4-acpy = 4-acetylpyridine) have been structurally and magnetically characterized. Compound 1 crystallizes in the orthorhombic system Fddd space group and consists of a single end-to-end azido-bridged chain with the Co(II) atoms in a CoN5O slightly distorted octahedron. Compound 2 crystallizes in the monoclinic system P21/a space group and shows 2D sheets built up through end-to-end azido bridges with the Co(II) atoms in a CoN6 environment. The magnetic properties of 1 and 2 are reported. In the high-temperature region, the plots of χM or χMT vs T for 1 and 2 compounds can be fitted by using the Curie−Weiss law, and the best-fit ϑ values are −69.1 and −22.6 K, respectively. For 2 magnetic ordering and spontaneous magnetization is achieved below Tc = 25 K

Antiferromagnetic Alternating and Homogeneous Manganese−Azido Chains: Structural Characterization and Magnetic Behavior of Two New One-Dimensional [Mn(L)₂(μ_1,3-N₃)₂]<i>_n</i>Compounds (L = 3-Ethylpyridine and 2-Hydroxypyridine)

The X-ray structures of the two monodimensional systems of formula [Mn(L)2(N3)2]n in which L = 3-ethylpyridine (1) or 2-hydroxypyridine (2) have been determined. Crystal data:  1, formula C14H18MnN8, monoclinic P21/n, a = 10.210(5) Å, b = 15.460(6) Å, c = 10.880(4) Å, β = 95.86(3)°, Z = 4; 2, formula C10H10MnN8O2, triclinic P1̄, a = 5.218(2) Å, b = 6.841(3) Å, c = 9.469(4) Å, α = 79.30(4)°, β = 87.85(4)°, γ = 75.85(4)°, Z = 1. The two compounds consist of chains of manganese atoms bridged by double end-to-end azido bridges. 1 consists of a structurally and magnetically alternated chain whereas 2 is a homogeneous system. Magnetic measurements show antiferromagnetic interaction with J values −13.8/−11.7 and −7.0 cm-1 for 1 and 2, respectively. The deformation of the Mn2(N3)2 eight-membered rings from planarity to chair conformation has been correlated to the magnitude of the antiferromagnetic coupling constant by means of extended Hückel MO calculations

Molecular, 1D, and 2D Systems Built from Phenylcyanamido Ligands. Syntheses, Crystal Structures, and Characterization of Their Magnetic Properties

Several MnII compounds with phenylcyanamido ligands have been synthesized and characterized by means of single-crystal X-ray structural determination. The reported compounds show a wide variety of nuclearity from mononuclear and dinuclear systems to 1D chains and 2D networks in which X-phenylcyanamide (X-pcyd) anions act as the bridging ligand. Mononuclear compound [Mn(H2O)2(4-bzpy)2(3-Cl-pcyd)2] (1) crystallizes in the monoclinic system, P21/a space group, dinuclear compounds (μ1,3-3-Cl-pcyd)2[Mn(2,2‘-bpy)(3-Cl-pcyd)(MeOH)]2 (2) and (μ1,3-3-Cl-pcyd)2[Mn(2,2‘-bpy)(3-Cl-pcyd)(EtOH)]2 (3) crystallize in the triclinic system, P1̄ space group, 1D chain {(μ1,3-4-Cl-pcyd)2[Mn(2,2‘-bpy)]}n (4) crystallizes in the monoclinic system, I2/a space group, and 2D network [Mn(μ-4,4‘-bpy)(μ1,3-3-F-pcyd)2]n (5) crystallizes in the monoclinic system, C2 space group. Susceptibility measurements on compounds 2−4 reveal moderate antiferromagnetic coupling in all cases. MO calculations have been made to elucidate the main factors that control the superexchange pathway for this kind of ligand. Comparison of their magnetic behavior with that of related ligands such as azido and dicyanamido is reported

1D and 2D End-to-End Azide-Bridged Cobalt(II) Complexes: Syntheses, Crystal Structures, and Magnetic Properties

Two new polynuclear azido-bridged Co(II) compounds with formulas catena-[Co(μ1,3-N3)(N3)(py)2(H2O)]n (1) and [Co(μ1,3-N3)2(4-acpy)2]n (2) (py = pyridine, 4-acpy = 4-acetylpyridine) have been structurally and magnetically characterized. Compound 1 crystallizes in the orthorhombic system Fddd space group and consists of a single end-to-end azido-bridged chain with the Co(II) atoms in a CoN5O slightly distorted octahedron. Compound 2 crystallizes in the monoclinic system P21/a space group and shows 2D sheets built up through end-to-end azido bridges with the Co(II) atoms in a CoN6 environment. The magnetic properties of 1 and 2 are reported. In the high-temperature region, the plots of χM or χMT vs T for 1 and 2 compounds can be fitted by using the Curie−Weiss law, and the best-fit ϑ values are −69.1 and −22.6 K, respectively. For 2 magnetic ordering and spontaneous magnetization is achieved below Tc = 25 K

Crystal Structure and Magnetic Behavior of Two New Dinuclear Carbonato-Bridged Copper(II) Compounds. Superexchange Pathway for the Different Coordination Modes of the Carbonato Bridge in Polynuclear Copper(II) Compounds

Four new μ-CO32- copper(II) complexes with different coordination modes for the carbonato bridge have been obtained by fixation of atmospheric CO2:  {(μ3-CO3)[Cu3(ClO4)3(Et3dien)3]}(ClO4) (1), Et3dien = N,N‘,N‘‘-triethylbis(2-aminoethane)amine; {(μ-CO3)[Cu2(H2O)(Et4dien)2]}(ClO4)2·H2O (2), Et4dien = N,N,N‘‘,N‘‘-tetraethyl-bis(2-aminoethane)amine; {(μ-CO3)[Cu2(H2O)2(EtMe4dien)2]} (ClO4)2·2H2O (3), EtMe4dien = N‘-ethyl-N,N,N‘‘,N‘‘-tetramethylbis(2-aminoethane)amine; and {(μ-CO3)[Cu2(H2O)(Me5dien)2]}(ClO4)2·H2O (4), Me5dien = N,N,N‘,N‘‘,N‘‘-pentamethylbis(2-aminoethane)amine. The crystal structures have been solved for 2, monoclinic system, space group P21/n, formula [C25H62Cl2Cu2N6O13] with a = 12.763(6) Å, b = 25.125(8) Å, c = 13.261(4) Å, β = 111.85(3)°, Z = 4, and for 3, triclinic system, space group P1̄, formula [C21H58Cl2Cu2N6O15] with a = 8.412(3) Å, b = 14.667(4) Å, c = 16.555(5) Å, α = 99.66(2)°, β = 102.14(2)°, γ = 104.72(2)°, Z = 2. Susceptibility measurements show ferromagnetic behavior (J = +6.7(6) cm-1) for the trinuclear compound 1 whereas 2−4 are antiferromagnetically coupled with J = −17.8(8), −125.5(9), and −21.2(3) cm-1 respectively. Certain synthetic aspects that may be related to the nuclearity of the copper(II) μ-CO32- compounds and the superexchange pathway for the different coordination modes of the carbonato bridge are discussed

Two New One-Dimensional Compounds with End-to-End Dicyanamide as a Bridging Ligand: Syntheses and Structural Characterization of <i>trans</i>-[Mn(4-bzpy)₂(N(CN)₂)₂]<i>_n</i> and <i>cis</i>-[Mn(Bpy)(N(CN)₂)₂]<i>_n</i>, (4-bzpy = 4-benzoylpyridine; bpy = 2,2‘-bipyridyl)

Two new one-dimensional compounds, trans-[Mn(4-bzpy)2(N(CN)2)2]n (1) and cis-[Mn(bpy)(N(CN)2)2]n (2), have been synthesized and studied from a magnetic point of view (4-bzpy = 4-benzoylpyridine; bpy = 2,2‘-bipyridyl). The crystal structures of 1 and 2 have been solved. Compound 1 crystallizes in the monoclinic system, P21/n group, a = 6.374(2) Å, b = 7.584(2) Å, c = 26.766(5) Å, β = 91.87°, and Z = 2, whereas compound 2 crystallizes in the monoclinic system, C2/c group, a = 6.707(2) Å, b = 17.188(5) Å, c = 13.096(5) Å, β = 90.54°, and Z = 4. The two compounds consist of chains with double μ1,5-dicyanamide bridges between neighboring manganese(II) atoms. The weak antiferromagnetic coupling found for the two compounds (J = −0.3 cm-1 for 1 and −0.4 cm-1 for 2) has been studied by MO analysis, and the superexchange pathway through the μ1,5-(NCNCN-) bridge has been compared with the shorter μ1,3-(NNN-)

Two New One-Dimensional Compounds with End-to-End Dicyanamide as a Bridging Ligand: Syntheses and Structural Characterization of <i>trans</i>-[Mn(4-bzpy)₂(N(CN)₂)₂]<i>_n</i> and <i>cis</i>-[Mn(Bpy)(N(CN)₂)₂]<i>_n</i>, (4-bzpy = 4-benzoylpyridine; bpy = 2,2‘-bipyridyl)

Two new one-dimensional compounds, trans-[Mn(4-bzpy)2(N(CN)2)2]n (1) and cis-[Mn(bpy)(N(CN)2)2]n (2), have been synthesized and studied from a magnetic point of view (4-bzpy = 4-benzoylpyridine; bpy = 2,2‘-bipyridyl). The crystal structures of 1 and 2 have been solved. Compound 1 crystallizes in the monoclinic system, P21/n group, a = 6.374(2) Å, b = 7.584(2) Å, c = 26.766(5) Å, β = 91.87°, and Z = 2, whereas compound 2 crystallizes in the monoclinic system, C2/c group, a = 6.707(2) Å, b = 17.188(5) Å, c = 13.096(5) Å, β = 90.54°, and Z = 4. The two compounds consist of chains with double μ1,5-dicyanamide bridges between neighboring manganese(II) atoms. The weak antiferromagnetic coupling found for the two compounds (J = −0.3 cm-1 for 1 and −0.4 cm-1 for 2) has been studied by MO analysis, and the superexchange pathway through the μ1,5-(NCNCN-) bridge has been compared with the shorter μ1,3-(NNN-)