A Series of Cu^II-Azide Polymers of Cu₆ Building Units and the Role of Chelating Diamine in Controlling their Dimensionality: Synthesis, Structures, and Magnetic Behavior

Four new neutral copper-azido polymers [Cu6(N3)12(aem)2]n(1), [Cu6(N3)12(dmeen)2(H2O)2]n (2), [Cu6(N3)12(N,N′-dmen)2]n (3), and [Cu6(N3)12(hmpz)2]n (4) [aem = 4-(2-aminoethyl)morpholine; dmeen = N,N-dimethyl-N′-ethylethylenediamine; N,N′-dmen = N,N′-dimethylethylenediamine and hmpz = homopiperazine] have been synthesized by using 0.33 mol equiv of the chelating diamine ligands with Cu(NO3)2·3H2O/CuCl2·2H2O and an excess of NaN3. Single crystal X-ray structures show that the basic unit of these complexes, especially 1−3, contains very similar CuII6 building blocks. But the overall structures of these complexes vary widely in dimensionality. While 1 is three-dimensional (3D) in nature, 2 and 3 have a two-dimensional (2D) arrangement (with different connectivity) and 4 has a one-dimensional (1D) structure. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in all the four complexes. The experimental susceptibility data have been analyzed by some theoretical model equations

A Series of Cu^II-Azide Polymers of Cu₆ Building Units and the Role of Chelating Diamine in Controlling their Dimensionality: Synthesis, Structures, and Magnetic Behavior

Four new neutral copper-azido polymers [Cu6(N3)12(aem)2]n(1), [Cu6(N3)12(dmeen)2(H2O)2]n (2), [Cu6(N3)12(N,N′-dmen)2]n (3), and [Cu6(N3)12(hmpz)2]n (4) [aem = 4-(2-aminoethyl)morpholine; dmeen = N,N-dimethyl-N′-ethylethylenediamine; N,N′-dmen = N,N′-dimethylethylenediamine and hmpz = homopiperazine] have been synthesized by using 0.33 mol equiv of the chelating diamine ligands with Cu(NO3)2·3H2O/CuCl2·2H2O and an excess of NaN3. Single crystal X-ray structures show that the basic unit of these complexes, especially 1−3, contains very similar CuII6 building blocks. But the overall structures of these complexes vary widely in dimensionality. While 1 is three-dimensional (3D) in nature, 2 and 3 have a two-dimensional (2D) arrangement (with different connectivity) and 4 has a one-dimensional (1D) structure. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in all the four complexes. The experimental susceptibility data have been analyzed by some theoretical model equations

Cu^II-Azide Polynuclear Complexes of Three Different Building Clusters with the Same Schiff-Base Ligand: Synthesis, Structures, Magnetic Behavior, and Density Functional Theory Studies

Three copper-azido complexes [Cu₄(N₃)₈(L¹)₂­(MeOH)₂]_<i>n</i> (<b>1</b>), [Cu₄(N₃)₈(L¹)₂] (<b>2</b>), and [Cu₅(N₃)₁₀(L¹)₂]_<i>n</i> (<b>3</b>) [L¹ is the imine resulting from the condensation of pyridine-2-carboxaldehyde with 2-(2-pyridyl)­ethylamine] have been synthesized using lower molar equivalents of the Schiff base ligand with Cu­(NO₃)₂·3H₂O and an excess of NaN₃. Single crystal X-ray structures show that the basic unit of the complexes <b>1</b> and <b>2</b> contains Cu^II₄ building blocks; however, they have distinct basic and overall structures due to a small change in the bridging mode of the peripheral pair of copper atoms in the linear tetranuclear structures. Interestingly, these changes are the result of changing the solvent system (MeOH/H₂O to EtOH/H₂O) used for the synthesis, without changing the proportions of the components (metal to ligand ratio 2:1). Using even lower proportions of the ligand, another unique complex was isolated with Cu^II₅ building units, forming a two-dimensional complex (<b>3</b>). Magnetic susceptibility measurements over a wide range of temperature exhibit the presence of both antiferromagnetic (very weak) and ferromagnetic exchanges within the tetranuclear unit structures. Density functional theory calculations (using B3LYP functional, and two different basis sets) have been performed on the complexes <b>1</b> and <b>2</b> to provide a qualitative theoretical interpretation of their overall magnetic behavior

Cu^II-Azide Polynuclear Complexes of Three Different Building Clusters with the Same Schiff-Base Ligand: Synthesis, Structures, Magnetic Behavior, and Density Functional Theory Studies

Three copper-azido complexes [Cu₄(N₃)₈(L¹)₂­(MeOH)₂]_<i>n</i> (<b>1</b>), [Cu₄(N₃)₈(L¹)₂] (<b>2</b>), and [Cu₅(N₃)₁₀(L¹)₂]_<i>n</i> (<b>3</b>) [L¹ is the imine resulting from the condensation of pyridine-2-carboxaldehyde with 2-(2-pyridyl)­ethylamine] have been synthesized using lower molar equivalents of the Schiff base ligand with Cu­(NO₃)₂·3H₂O and an excess of NaN₃. Single crystal X-ray structures show that the basic unit of the complexes <b>1</b> and <b>2</b> contains Cu^II₄ building blocks; however, they have distinct basic and overall structures due to a small change in the bridging mode of the peripheral pair of copper atoms in the linear tetranuclear structures. Interestingly, these changes are the result of changing the solvent system (MeOH/H₂O to EtOH/H₂O) used for the synthesis, without changing the proportions of the components (metal to ligand ratio 2:1). Using even lower proportions of the ligand, another unique complex was isolated with Cu^II₅ building units, forming a two-dimensional complex (<b>3</b>). Magnetic susceptibility measurements over a wide range of temperature exhibit the presence of both antiferromagnetic (very weak) and ferromagnetic exchanges within the tetranuclear unit structures. Density functional theory calculations (using B3LYP functional, and two different basis sets) have been performed on the complexes <b>1</b> and <b>2</b> to provide a qualitative theoretical interpretation of their overall magnetic behavior

New Structural Topologies in a Series of 3d Metal Complexes with Isomeric Phenylenediacetates and 1,3,5-Tris(1-imidazolyl)benzene Ligand: Syntheses, Structures, and Magnetic and Luminescence Properties

In this article we present the syntheses, characterizations, magnetic and luminescence properties of five 3d-metal complexes, [Co­(tib)­(1,2-phda)]_<i>n</i>­·(H₂O)_<i>n</i> (<b>1</b>), [Co₃(tib)₂­(1,3-phda)₃­(H₂O)]_<i>n</i>­·(H₂O)_2<i>n</i> (<b>2</b>), [Co₅(tib)₃­(1,4-phda)₅­(H₂O)₃]_<i>n</i>­·(H₂O)_7<i>n</i> (<b>3</b>), [Zn₃(tib)₂­(1,3-phda)₃]_<i>n</i>­·(H₂O)_4<i>n</i> (<b>4</b>), and [Mn­(tib)₂­(H₂O)₂]_<i>n</i>­·(1,4-phdaH)_2<i>n</i>­·(H₂O)_4<i>n</i> (<b>5</b>), obtained from the use of isomeric phenylenediacetates (phda) and the neutral 1,3,5-tris­(1-imidazolyl)­benzene (tib) ligand. Single crystal X-ray structures showed that <b>1</b> constitutes 3,5-connected 2-nodal nets with a double-layered two-dimensional (2D) structure, while <b>2</b> forms an interpenetrated 2D network (3,4-connected 3-nodal net). Complex <b>3</b> has a complicated three-dimensional structure with 10-nodal 3,4,5-connected nets. Complex <b>4</b>, although it resembles <b>2</b> in stoichiometry and basic building structures, forms a very different overall 2D assembly. In complex <b>5</b> the dicarboxylic acid, upon losing only one of the acidic protons, does not take part in coordination; instead it forms a complicated hydrogen bonding network with water molecules. Magnetic susceptibility measurements over a wide range of temperatures revealed that the metal ions exchange very poorly through the tib ligand, but for the Co­(II) complexes the effects of nonquenched orbital contributions are prominent. The 3d¹⁰ metal complex <b>4</b> showed strong luminescence with λ_max = 415 nm (for λ_ex = 360 nm)

New Structural Topologies in a Series of 3d Metal Complexes with Isomeric Phenylenediacetates and 1,3,5-Tris(1-imidazolyl)benzene Ligand: Syntheses, Structures, and Magnetic and Luminescence Properties

In this article we present the syntheses, characterizations, magnetic and luminescence properties of five 3d-metal complexes, [Co­(tib)­(1,2-phda)]n­·(H2O)n (1), [Co3(tib)2­(1,3-phda)3­(H2O)]n­·(H2O)2n (2), [Co5(tib)3­(1,4-phda)5­(H2O)3]n­·(H2O)7n (3), [Zn3(tib)2­(1,3-phda)3]n­·(H2O)4n (4), and [Mn­(tib)2­(H2O)2]n­·(1,4-phdaH)2n­·(H2O)4n (5), obtained from the use of isomeric phenylenediacetates (phda) and the neutral 1,3,5-tris­(1-imidazolyl)­benzene (tib) ligand. Single crystal X-ray structures showed that 1 constitutes 3,5-connected 2-nodal nets with a double-layered two-dimensional (2D) structure, while 2 forms an interpenetrated 2D network (3,4-connected 3-nodal net). Complex 3 has a complicated three-dimensional structure with 10-nodal 3,4,5-connected nets. Complex 4, although it resembles 2 in stoichiometry and basic building structures, forms a very different overall 2D assembly. In complex 5 the dicarboxylic acid, upon losing only one of the acidic protons, does not take part in coordination; instead it forms a complicated hydrogen bonding network with water molecules. Magnetic susceptibility measurements over a wide range of temperatures revealed that the metal ions exchange very poorly through the tib ligand, but for the Co­(II) complexes the effects of nonquenched orbital contributions are prominent. The 3d10 metal complex 4 showed strong luminescence with λmax = 415 nm (for λex = 360 nm)

Molecular Marriage through Partner Preferences in Covalent Cage Formation and Cage-to-Cage Transformation

Unprecedented self-sorting of three-dimensional purely organic cages driven by dynamic covalent bonds is described. Four different cages were first synthesized by condensation of two triamines and two dialdehydes separately. When a mixture of all the components was allowed to react, only two cages were formed, which suggests a high-fidelity self-recognition. The issue of the preference of one triamine for a particular dialdehyde was further probed by transforming a non-preferred combination to either of the two preferred combinations by reacting it with the appropriate triamine or dialdehyde

Two Novel Heterometallic Chains Featuring Mn^II and Na^I Ions in Trigonal-Prismatic Geometries Alternately Linked to Octahedral Mn^IV Ions: Synthesis, Structures, and Magnetic Behavior

Two new one-dimensional heterometallic complexes, [Mn₃Na­(L)₄(CH₃CO₂)­(MeOH)₂]­(ClO₄)₂·3H₂O (<b>1</b>), [Mn₃Na­(L)₄(CH₃CH₂CO₂)­(MeOH)₂]­(ClO₄)₂·2MeOH·H₂O (<b>2</b>) [LH₂ = 2-methyl-2-(2-pyridyl)­propane-1,3-diol], have been synthesized and characterized by X-ray crystallography. Both complexes feature Mn^II and Na^I ions in trigonal-prismatic geometries that are linked to octahedral Mn^IV ions by alkoxy bridges. Variable-temperature direct- and alternating-current magnetic susceptibility data indicated a spin ground state of <i>S</i> = ¹¹/₂ for both complexes. Density functional theory calculations performed on <b>1</b> supported this conclusion

Cu^II-Azide Polymers of Cu₃ and Cu₆ Building Units: Synthesis, Structures, and Magnetic Exchange Mechanism

Two new neutral copper-azido polymers [Cu3(N3)6(tmen)2]n (1) and [Cu6(N3)12(deen)2]n (2) [tmen = N,N,N′,N′-tetramethylethylenediamine and deen = N,N′-diethylethylenediamine] have been synthesized by using lower molar equivalents of the chelating diamine ligands with Cu(NO3)2·3H2O and an excess of NaN3. The single crystal X-ray structure shows that in the basic unit of the 1D complex 1, the three CuII ions are linked by double end-on azido bridges with Cu−NEO−Cu angles on both sides of the magnetic exchange critical angle of 108°. Complex 2 is a 3D framework of a basic Cu6 cluster. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in both the complexes. Density functional theory calculations (B3LYP functional) have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the overall ferromagnetic behavior shown by the complex 1

Molecular Marriage through Partner Preferences in Covalent Cage Formation and Cage-to-Cage Transformation

Unprecedented self-sorting of three-dimensional purely organic cages driven by dynamic covalent bonds is described. Four different cages were first synthesized by condensation of two triamines and two dialdehydes separately. When a mixture of all the components was allowed to react, only two cages were formed, which suggests a high-fidelity self-recognition. The issue of the preference of one triamine for a particular dialdehyde was further probed by transforming a non-preferred combination to either of the two preferred combinations by reacting it with the appropriate triamine or dialdehyde