Antiferromagnetic Coupling In A (μ-Hydroxo)(μ-Pyrazolato)Dicopper(II) Complex. Synthesis, Crystal Structure, Magnetic Properties, And Theoretical Studies

Preparation, crystal structure and magnetic properties of a 3,5-dimethylpyrazolate bridged binuclear copper(II) complex [Cu2(L1)(3,5 prz)] (L1 = 1,3-Bis(2-hydroxy-1-napthylideneamino) propan-2-ol) (1) are reported. Variable-temperature magnetic susceptibility measurements for a powdered sample of the complex were carried out in the temperature range 5 - 350 K and analysed to obtain values of the parameter J in the exchange Hamiltonian H = -2JS1·S2 . In the dicopper(II) complex [Cu2(L2)(3,5 prz)], (L2 = l,3-Bis(2-hydroxy-5-chlorosalicylideneamino) propan-2-ol) (2) reported recently the antiferromagnetic interaction is much less than that of 1 (-27 = 440 cm-1 ), as result which is difficult to explain in terms of structural factors on the basis of widely accepted criteria. The differences in the magnetic behaviour now have been rationalized using the “ligand orbital complementary” concept

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Importance of Orbital Complementarity in Spin Coupling through Two Different Bridging Groups. Synthesis, Crystal Structure, Magnetic Properties and Magneto-Structural Correlations in a Dicopper(II) Complex of Endogenous Alkoxo Bridging Ligand with Exogenous Pyrazolate

Zeitschrift für Naturforschung B ◽

10.1515/znb-2001-1106 ◽

2001 ◽

Vol 56 (11) ◽

pp. 1129-1137 ◽

Cited By ~ 9

Author(s):

Y. Elerman ◽

H. Karab ◽

A. Elmali

Keyword(s):

Crystal Structure ◽

Variable Temperature ◽

Magnetic Behaviour ◽

Spin Coupling ◽

Powdered Sample ◽

Structural Factors ◽

Bridging Ligand ◽

Ligand Orbital ◽

Bridging Groups ◽

Super Exchange Interaction

[Cu2(L3)(3,5-prz)] (L3 = 1,3-bis(2-hydroxy-4-methoxybenzylideneamino)-propan-2-ol) (3) was synthesized and its crystal structure determined. The compound consists of discrete binuclear units, in which copper atoms are linked by the alkoxide oxygen atom of the ligand and the pyrazolate nitrogen atoms. Variable-temperature magnetic susceptibility measurements for a powdered sample of the complex were carried out in the temperature range 4.4 - 308 K and analysed to obtain values of the parameter J in the exchange Hamiltonian H = -2JS1-S2. Recently, the dicopper(II) complexes [Cu2(L1)(3,5-prz)] (L1 = 1,3-bis(2-hydroxy-1-napthylideneamino)- propan-2-ol) (1) and [Cu2(L2)(3,5-prz)], (L2 = 1,3-bis(2-hydroxy-5-chlorosalicylideneamino)- propan-2-ol) (2) were reported. These compounds show antiferromagnetic behaviour (-2J: 444 cm-1 for 1 164 cm-1 for 2, and 472 cm-1 for 3). The strength of the super-exchange interaction (-2J) of 2 is much less than that of 1 and 3, a result which is difficult to explain in terms of structural factors on the basis of widely accepted criteria. The differences in the magnetic behaviour have been rationalized in terms of the bridging ligand orbital complementary / countercomplementary concept.

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Synthesis, Crystal Structure and Magnetic Properties of a (μ-Hydroxo)(μ-Pyrazolato) Dicopper(II) Complex

Zeitschrift für Naturforschung B ◽

10.1515/znb-2000-0903 ◽

2000 ◽

Vol 55 (9) ◽

pp. 796-802 ◽

Cited By ~ 8

Author(s):

H. Kara ◽

Y. Elerman ◽

K. Prout

Keyword(s):

Crystal Structure ◽

Magnetic Properties ◽

Variable Temperature ◽

Powdered Sample ◽

X Ray Diffraction ◽

Triclinic Space Group ◽

X Ray ◽

Present Complex ◽

Square Planar ◽

Super Exchange Interaction

Preparation and magnetic properties of a 3,5-dimethylpyrazolate bridged binuclear copper(II) complex [Cu2(L)(3 ,5 -pyz)] (L = 1,3-Bis(2-Hydroxy-5-Chlorosalicylideneamino)propan- 2-ol) is reported. The crystal structure determined by X-ray diffraction methods. (C22H20N4O3CI2CU2), triclinic, space group P1̄, a = 9.622(3), b = 10.921(2), c = 11.420(3) Å, α = 100.73(2), β = 94.04(2), Υ = 108.08(2)°, V = 1110.2(5) Å3, Z = 2. Two copper(II) ions in a square-planar coordination are bridged via alkoxide oxygen and 3,5-dimethyl pyrozolate nitrogen atoms to form a dinuclear unit. The metal coordination sphere is four-coordinate, planar with an N2O2 donor set. The dihedral angle between the two coordination planes is 166.83°. There are significant intermolecular interactions between neighbouring binuclear entities. The shortest intermolecular Cu (1) ... Cu(1)i distance is 3.383(1) Å and the Cu(1) - O ( 1)i distance is 2.666(3) Å (i = 1 -x, -y, 1 - z). The variable-temperature magnetic susceptibility measurement for a powdered sample of the complex was carried out in the temperature range 5 - 350 K and analysed to obtain values of the parameter J in the exchange Hamiltonian ℋ = -2JScu Scu; 2J = -164 cm-1. The magnetic moment at 300 K is about 2.42 μB, and 0.22 μB at 5 K. The weak antiferromagnetism of the present complex is reasonably explained in terms of the orbital countercomplementary effect based on Hoffmann's theory for super-exchange interaction

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