J. Jaud

Crystal structure and magnetic and EPR properties of the heterobinuclear complex CuNi(fsa)2en(H2O)2.H2O (H4(fsa)2en = N,N'-bis(2-hydroxy-3-carboxybenzylidene)-1,2,-diaminoethane)

The goal of this paper is to investigate the exchange interaction in CuNi(fsa)2en(H2O)2·H2O, denoted [CuNi], where (fsa)2en4− is the bichelating ligand derived from the Schiff base N,N′-(1-hydroxy-2-carboxybenzylidene)-1,2-diaminoethane. For a comparison of the structure of the pair states in [CuNi] with those of Cu(II) and Ni(II) single-ion ground states, CuMg(fsa)2en(H2O)2·H2O and Ni2(fsa)2en(H2O)2·H2O, denoted [CuMg] and [NiNi], have also been investigated. The crystal structure of [CuNi] has been solved at −120 °C from 8428 reflections. [CuNi] crystallizes in the trigonal system, space group P31. The lattice constants are a = 12.8071 (4) A and c = 9.8157 (8) A with Z = 3. The structure is made of [CuNi] binuclear units, in which the copper atom is in a strictly planar −N2O2 environment and the nickel atom in a pseudooctahedral −O2O2(H2O)2 environment. The crystal structure of [NiNi] has been solved at room temperature from 3262 reflections. The space group is P32, and the structure of the binuclear units [NiNi] is very close to that of the units [CuNi]. The temperature dependence of the magnetic susceptibility of [CuNi], studied in the temperature range 4–300 K, has revealed an energy gap of −3J/2 = 213 cm−1 between the 2A1 ground state and the 4A1 excited state. The average values of the g factors for the two pair states have been compared to those of the single ions, as deduced from the magnetic behavior of [CuMg] and [NiNi]. The EPR powder spectrum of [CuNi] is typical of an axial symmetry. The single-crystal spectra at 4 K exhibit only one signal for any orientation, assigned to the ground-pair doublet state. The g tensor is axial with the unique axis perpendicular to the N2CuO2NiO2 pseudo molecular plane. The principal values are g∥ = 2.22 (5) and g⊥ = 2.30 (0). The signal broadens out against the temperature in an inhomogeneous manner, the broadening being more pronounced on the high-field side. The magnetic and the EPR data are compared. The status of the spin Hamiltonian utilized to interpret these data is discussed. Finally, the mechanism of the exchange interaction is specified. The existence of two exchange pathways, namely, [formula omitted] and [formula omitted], the former being antiferromagnetic and the latter ferromagnetic, is emphasized.

Study of new lanthanide complexes of 2,6-pyridinedicarboxylate: synthesis, crystal structure of Ln(Hdipic)(dipic) with Ln=Eu, Gd, Tb, Dy, Ho, Er, Yb, luminescence properties of Eu(Hdipic)(dipic)

Abstract This paper presents the hydrothermal synthesis of a series of new isomorphous bis-dipicolinato lanthanide complexes: Ln(Hdipic)(dipic) with Ln=Eu, Gd, Tb, Dy, Ho, Er, Yb, and dipic=2,6-pyridinedicarboxylate. A structural study has been realised for the Ho3+ complex. It crystallises in a two-dimensional network, where sheets are parallel to the (100) plane. The luminescent properties of the analogous Eu3+ complex have been investigated. The composition of the 7FJ levels is consistent with a true C1 local symmetry: six oxygen and two nitrogen atoms forming a distorted square antiprism. The 5D0 emission lifetime is only slightly shorter than in [Eu(dipic)3]3− in solution, but the ligand to metal energy transfer is much less efficient.

Octahedral μ-oxalato-nickel(II) dinuclear complexes with watet and tridentate amines as blocking ligands: magnetostructural correlations

Abstract Three nickel(II) dinuclear oxalato (ox) bridged compounds: (μ-ox)[Ni(dpt)(H2O)]2(ClO4)2 (1), (μ-ox)[Ni(Medpt)(H2O)]2(ClO4)2·2H2O (2) and (μ-ox)[Ni(ept)(H2O)]2(ClO4)2 (3) have been synthesized and characterized where dpt is bis(3-aminopropyl)amine, Medpt is 3,3′-diamino-N-methyl-dipropylamine and ept is N-(2-aminoethyl)-1,3-propanediamine. The crystal structures of 1 and 2 have been solved. Complex 1 crystallizes in the monoclinic system, space group I2/a, with FW=702.8, a=12.534(4), b=16.871(5), c=13.450(4) A, β=95.28(7)°, V=2831(3) A3, Z=4, R=0.063 and Rw=0.068. Complex 2 crystallizes in the monoclinic system, space group P21/n, with FW=766.9, a=6.404(2), b=13.333(4), c=18.687(4) A, β=97.67(8)°, V=1576(2) A, Z=2, R=0.063 and Rw=0.068. In both complexes the nickel atom is placed in a distorted octahedral environment. The magnetic properties of these compounds have been investigated. The χMT versus T plots for 1–3 exhibit the typical shapes for antiferromagnetically coupled nickel(II) dinuclear complexes. The J values for 1–3 were −24.7, −21.6 and −25.0 cm−1, respectively. These values are significantly lower than those reported for nickel(II) dinuclear complexes when the blocking ligands have four N atoms. The influence of the change in the electronegativity of the peripheral ligand atoms on the magnetic behaviour has been studied by means of extended-Huckel calculations.

Polymeric copper(II)-orotato complexes, [(C5H2N2O4)Cu(H2O)2]n

The compound [(C5H2N2O4)Cu(H2O)2]n has been synthesized and its structure determined at room temperature. The primary coordination sphere at the Cu ion is square planar with the orotate dianion coordinating at the metal through heterocyclic nitrogen atom and adjacent oxygen of the carboxylate group, the remaining coordination sites are occupied by two water molecules. The orotate dianion is tricoordinated to one copper via N1 and one oxygen of the carboxylato group and to another copper atom via the other oxygen of the carboxylato group. The coordination at copper is extended to five by the other oxygen of the carboxylate group of another orotate molecule. Thus, the molecules are associated to form chains, the carboxylato group acting as a bridge between the metal ions, the orotato-group being tridentate. The title compound crystallizes in the monoclinic space group. P21/n1 with a = 9.515(5), b = 6.925(2), c = 11.861(6) Å, β = 95.285(9)°, Dcalc = 2.17 g cm−3, and z = 4.

Crystal structure and magnetic properties of Cu2(fsa)2en, CH3OH, with H4(fsa)2en = N,N′-bis(2-hydroxy, 3-carboxybenzilidene)-1,2-diaminoethane

Abstract The title compound Cu 2 (fsa) 2 en, CH 3 OH was synthesized and its crystal structure solved at room temperature from 3830 independent reflections. It crystallizes in the monoclinic system, space group P2 1 /n. The lattice constants are a = 11.456(5) A, b = 11.425(3) A, c = 14.357(4) A and β = 104.15(3)° with Z = 4. Least squares refinement of the structure led to a conventional weighted R factor of 0.043. The structure is made of non-symmetrical binuclear units in which a copper atom is five-fold coordinated to two nitrogens, two phenolic oxygens and an oxygen of the methanol molecule, the other copper atom being coordinated to two phenolic oxygens and two carboxylic oxygens in a plannar manner. The temperature dependence of the magnetic susceptibility, studied in the range 10–312 K, showed a strong antiferromagnetic coupling with a J singlet-triplet separation of −650 cm −1 . This magnetic behaviour was compared to those of the other binuclear complexes with the same Cu 2 O 2 network and an explanation for such a strong coupling was proposed.

Crystal structure of NH3(CH2)2NH3BiCl5·2H2O

AbstractThe ethylenediammonium pentachlorobismuthate(III) dihydrate salt is monoclinic with the following unit cell dimensions: a = 10.902(8)Å, b = 7.926(6)Å, c = 15.199(6)Å, β = 96.40(1)°, space group P21/n with Z = 4. The structure shows a layer arrangement parallel to the

Crystal structure of NH3(CH2)2NH3(BiI4)2·4H2O

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Crystal and molecular structure of a new allotropic variety of the mega-spiro cyclophosphazene from diethylene glycol bis-(3-aminopropyl)-ether, N3P3Cl4[HN(CH2)3O(CH2)2O(CH2)2O(CH2)3 NH)]

axis: planes of the [Bi2Cl10]4− bioctahedra alternate with planes of [NH3(CH2)2NH3]2+ dications. The [Bi2Cl10]4− bioctahedra are connected through O(W)–H··· Cl hydrogen bonds, so that infinite unidimensional chains of composition [Bi2Cl10(H2O)2]n4n− are formed in the structure parallel to the