Magnetic coupling constants (2J) of hydroxo- and alkoxo-bridged copper binuclear compounds have been evaluated to determine the accuracy of different density functional methods and to study the magnetic behavior of these compounds. Comparison between the calculated and experimental coupling constants for the complete structures of five compounds shows that the most successful computational strategy is the combination of the B3LYP method with the broken-symmetry approach. Calculations for model compounds of both families yield reasonable approximations to the values of magnetic coupling constants calculated for the full molecular structures. Our calculations show a correlation between the magnetic coupling constant and the Cu−O−Cu bridging angle and with the out-of-plane displacement of the hydroxo or alkoxo groups, in agreement with the experimental data. The counterions of the hydroxo-bridged complexes, when hydrogen bonded to the bridging hydroxo group, determine the extent of the out-of-plane displacem...

Toward the Prediction of Magnetic Coupling in Molecular Systems: Hydroxo- and Alkoxo-Bridged Cu(II) Binuclear Complexes

Thiosemicarbazone complexes of copper(II): structural and biological studies

Factors affecting the magnetic properties of dimeric copper(II) complexes

The activation of small molecules by dinuclear complexes of copper and other metals

We have structurally and magnetically characterized a total of 12 complexes based on the Single-Molecule Magnet (SMM) [MnIII6O2(sao)6(O2CH)2(MeOH) 4] (1) (where sao2- is the dianion of salicylaldoxime or 2-hydroxybenzaldeyhyde oxime) that display analogous structural cores but remarkably different magnetic behaviors. Via the use of derivatized oxime ligands and bulky carboxylates we show that it is possible to deliberately increase the value of the spin ground state of the complexes [Mn6O2(Me-sao)6(O2CCPh3)2(EtOH)4] (2), [Mn6O2(Et-sao)6(O2CCMe3)2(EtOH)5] (3), [Mn6O2(Et-sao)6(O2CPh2OPh)2(EtOH)4] (4), [Mn6O2(Et-sao)6(O2CPh4OPh)2(EtOH)4(H2O)2] (5), [Mn6O2(Me-sao)6(O2CPhBr)2(EtOH)6] (6), [Mn6O2(Et-sao)6(O2CPh)2(EtOH)4(H2O)2] (7), [Mn6O2(Et-sao)6{O2CPh(Me)2}2(EtOH)6] (8), [Mn6O2(Et-sao)6(O2C11H15)2(EtOH)6] (9), [Mn6O2(Me-sao)6(O2C-th)2(EtOH)4(H2O)2] (10), [Mn6O2(Et-sao)6(O2CPhMe)2(EtOH)4(H2O)2] (11), and [Mn6O2(Et-sao)6(O2C12H17)2(EtOH)4(H2O)2] (12) (Et-saoH2 = 2-hydroxypropiophenone oxime, Me-saoH2 = 2-hydrox...

Toward a Magnetostructural Correlation for a Family of Mn6 SMMs

Bis(μ-carboxylato-O,O′)-diaquabis(1,10-phenanthroline)dicopper(II) dinitrate tetrahydrates, [Cu(RCOO)(phen)(H2O)]2(NO3)2·4H2O, where R=H, CH3, and (CH3)3C, were prepared and characterized by elemental analyses, electronic spectra, magnetic susceptibilities, and X-ray structure analysis. The magnetic susceptibility data conform to the usual dimer equation. The −2J values are 125 cm−1 for formate, 86 cm−1 for acetate, and 99 cm−1 for 2,2-dimethylpropanoate. The crystal structures of [Cu(HCOO)(phen)(H2O)]2(NO3)2·4H2O (1) and [Cu(CH3COO)(phen)(H2O)]2(NO3)2·4H2O (2) were determined by the single-crystal X-ray diffraction method. The crystallographic data are: Compound 1, monoclinic, I2⁄a, a=18.850(2), b=9.775(2), c=17.752(2) A, β=99.03(1)°, V=3230.4(8) A3, Z=4, R=0.055 for 2511 observed unique reflections; Compound 2, monoclinic, C2⁄c, a=18.563(4), b=14.272(5), c=14.126(3) A, β=106.72(2)°, V=3584(2) A3, Z=4, R=0.082 for 2092 reflections. The complexes consist of dimeric [Cu(RCOO)(phen)(H2O)]22+)] cations with ...

Structural, magnetic and spectroscopic characterization of novel di-μ-carboxylato-bridged binuclear copper(II) complexes with 1,10-phenanthroline

A new series of binuclear copper(II) complexes, [Fsal(=NenNR2)2Cu2X]2+ (R=Me and Et, X=Cl, Br, and OH), were synthesized, where Fsal(=NenNR2)2 indicates the Schiff base prepared from 2,6-diformyl-4-methylphenol and N,N-dialkylethylenediamine (alkyl=methyl(Me) and ethyl(Et)). Two copper(II) ions are connected with the phenolic oxygen and X. The complexes obtained were characterized by elemental analyses, infrared and visible spectra, molar conductivities in methanol, ESR spectra and magnetic susceptibilities. It was found that the stability of the complexes decreases in the order X=OH>>Br>Cl. It was concluded from cryomagnetic measurements that the effect of the bridging group X on spin-coupling decreases in the order OH>>Br>Cl.

Binuclear Metal Complexes. VI. Syntheses and Properties of Binuclear Copper(II) Complexes of 2,6-Bis[N-(β-dialkylaminoethyl)iminomethyl]-4-methylphenol

The reaction of cupric acetate with the reaction mixture of γ-aminopropyl alcohol and substituted salicylaldehydes in ethanol gave dimeric copper(II) complexes. The postulated structure of these complexes makes it possible to test the substituent effect transmitted to the coordinating atoms which are not in the superexchange pathway between copper-(II) ions in a pair. The magnetic moments observed at room temperature were corrected for the temperature variations to those at 25°C by graphic method based on Bleaney and Bowers’ equation. The observed substituent effect on the relation between μeff25°C and λmax is different from that observed for dimeric cupric halides complexes of substituted pyridine N-oxides. In these complexes the substituent effect transmits to the bridging oxygen atom in the superexchange pathway. As compared with the parent complex (H), methyl, chloro and benzo groups weakened the magnetic interaction but nitro group strengthened it. An interpretation of the substituent effect is given...

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Yoneichiro Muto

Papers

Factors affecting the magnetic properties of dimeric copper(II) complexes

Structural, magnetic and spectroscopic characterization of novel di-μ-carboxylato-bridged binuclear copper(II) complexes with 1,10-phenanthroline

Binuclear Metal Complexes. VI. Syntheses and Properties of Binuclear Copper(II) Complexes of 2,6-Bis[N-(β-dialkylaminoethyl)iminomethyl]-4-methylphenol

Magnetic Moments and d–d Bands of N-n-Propanolsalicylaldiminato-copper(II)

Magnetic and spectral studies on copper(II) complexes with N-hydroxyalkylsalicylideneimines