Crystal structure and magnetic properties of bis(2,2′-bipyridine) azido copper(II) perchlorate

The title compound has been synthesized and its crystal structure has been solved at room temperature. It crystallizes in the triclinic system, space groupP, witha=7.853(1) Å,b=10.177(1) Å,c=13.651(4) Å,=74.57(1)°,=88.49(1)°, =80.675(4)°, andZ=2. The structure consists of isolated [Cu(bipy)₂N₃]⁺ cations (bipy=2,2-bipyridine) and perchlorate anions. The metallic cation environment has a distorted trigonal-bipyramidal geometry. The EPR spectrum is rhombic, which indicates that the distortion with respect to the perfect trigonal bipyramid is sufficiently pronounced to mixz ²- andx ²–y ²-type orbitals in the ground state. The temperature dependence of the molar magnetic susceptibility has been investigated in the 300-2.2 K temperature range.     

Caro-Cryptands: Tris-carotenoid macrobicyclic ligands–synthesis,crystal structure,and dinuclear copper(I) complexes

The tris-carotenoid macrobicycles 1 and 2 were obtained in good yields in a one-step macrobicyclisation condensation between the tripode N(CH₂CH₂NH₂)₃ and the polyolefinic dialdehydes 5 and 6 . They form dinuclear cryptates by complexation of two Cu^I ions. The crystal structure of the tris-carotenoid compound 2 confirms that it contains three parallel polyolefinic strands. These substances may formally be considered as prototypes of molecular ‘cables’ formed by three electron-conducting molecular wires.     

Crystal and molecular structures of di-µ-azido-bis-[N,N,N′,N′-tetramethylethylenediamine azido copper(II)]

The title compound has been synthesized and its structure at room temperature has been solved. It crystallizes in the space groupP2₁/c, witha=9.581(5),b=13.746(4),c=8.869(1) Å, β=101.000(5)°, andZ=2. The structure was refined toR=0.029 from 1738 reflections. It consists of centrosymmetric dimeric units with two asymmetric end-to-end azido bridges. Each copper(II) ion is fivefold coordinated in the form of a slightly distorted square-based pyramid CuN₅. The apical position is occuped by a nitrogen atom of the azido bridge with a Cu-N apical bond of 2.456(6) Å. The Cu-N bond with the azido bridge in the basal plane is 1.979(5) Å. The intradimer Cu?Cu distance is 5.004(2) Å. The magnetic properties and the X-band EPR spectrum are interpreted in the light of these structural data.     

Crystal Structures of the Lanthanum(III), Europium(III), and Terbium(III) Cryptates of Tris(bipyridine) Macrobicyclic Ligands

The crystal structures of the La^III, Eu^III, and Tb^III complexes of macrobicyclic [bpy.bpy.bpy] ligands, [La³⁺ ? 1 ]3 Cl^? ( = 3- La), [Tb³⁺ ? 1 ]3 Cl^? ( = 3- Tb), and [Eu³⁺ ? 2 ]3 C1^? ( = 3- Eu), have been determined. They confirm the cryptate nature of these species, the cations being bound to the eight N-sites of the ligand. The macrobicycle presents two open faces, thus allowing additional coordination of two species, Cl^? ions or H₂O molecules, to the bound cations. These data provide structural support for the photophysical studies of the luminescent properties of the Eu^III and Tb^III cryptates, which indicated residual coordination of H₂O molecules.     

Crystal structure of di-μ-chloro-tetrakis(ethane-1,2-diamine)-dinickel(II) bis(tetraphenylboronate); relation between structure and magnetic properties

Summary The crystal structure of the title compound (Ni₂en₄Cl₂)(BPh₄)₂ was solved at room temperature from 3159 independent reflexions. The compound crystallizes in the monoclinic system, space group P2₁/c. The lattice constants area = 13.440(4) Å,b = 11.163(7) Å,c = 18.33(1) Å and = 107.39(5)° with Z = 2. Least squares refinement of the structure led to a conventional weighted R factor of 0.069. The structure consists of centrosymmetric [Ni₂en₄Cl₂]²⁺ dimeric entities and (BPh₄)^– counteranions. This structure is compared to those of (Ni₂en₄Cl₂)Cl₂ and (Ni₂en₄Cl₂)(ClO₄)₂ which possess the same dimeric entities. The Ni-Ni distance as well as the mean values of the Ni-Cl bonds vary according to: chloride > perchlorate > tetraphenylboronate. For the three compounds, the intradimer exchange interaction is of ferromagnetic nature and varies according to: chloride < perchlorate < tetraphenylborate. An interpretation of the magnetic behaviour variations in the series is proposed. It is founded on an estimation of the J_F ferromatgnetic contribution from the new concept of overlap density between magnetic orbitals.