Copper(II) Complexes with Subnormal Magnetic Moments

Kato, Michinobu; Jonassen, Hans B.; Fanning, James C.

doi:10.1021/cr60228a003

Cited by 683 publications

(151 citation statements)

References 88 publications

Supporting

Mentioning

137

Contrasting

Unclassified

Order By: Relevance

“…3a) [9][10][11][12]. Ils confirment en fait 1'existence de complexes binucl6aires, dans la phase cristalline, pour les savons a chaine paraffinique longue, comme cela avait ddja ete sugg6rd par des dtudes magndtiques rdalisdes sur une sdrie de savons de cuivre [18][19][20][21].…”

Section: To Cite This Versionunclassified

Etude par spectroscopie EXAFS au seuil K du cuivre des phases cristalline et colomnaire du stéarate de cuivre

et al. 1988

View full text Add to dashboard Cite

Résumé. 2014 La spectroscopie EXAFS au seuil K du cuivre a été utilisée pour décrire l'environnement local des atomes de cuivre dans les phases cristalline et mésomorphe colomnaire du stéarate de cuivre. Dans les colonnes de la phase mésomorphe, les groupes polaires s'empilent de manière très régulière ; les molécules de savon y interviennent à l'état dimérisé, formant des complexes binucléaires de géométrie « plan-carré » comme à l'état cristallin. Les atomes de cuivre sont beaucoup plus proches entre eux à l'intérieur d'un même dimère (2,7 Å) qu'entre deux dimères successifs (3,2 Å) le long de l'axe des colonnes de la phase mésomorphe. Abstract. 2014 Copper-K edge EXAFS spectroscopy has been used to probe the local environment of copper atoms in the crystalline and columnar mesomorphic phases of copper stearate. In the columns of the mesophase, polar groups are stacked one over the other very regularly ; the soap molecules are dimerized, and form binuclear complexes like in the crystalline state. The copper atoms are closer within a single dimer (2.7 Å) than between two successive dimers (3.2 Å) along the axis of the column in the mesophase.J. Phys. France 49 (1988) [345][346][347][348][349][350][351][352]

show abstract

Section: To Cite This Versionunclassified

Etude par spectroscopie EXAFS au seuil K du cuivre des phases cristalline et colomnaire du stéarate de cuivre

et al. 1988

View full text Add to dashboard Cite

show abstract

“…For two antiferromagnetically coupled S = 1/2 Cu(II) ions, the susceptibility will be a maximum at a temperature that is simply related to the energy difference, J, between the diamagnetic ground state and the paramagnetic excited state (7). Antiferromagnetic coupling between two copper ions has been observed in a wide variety of dimeric Cu(II) complexes (8) and in the four-copper derivative of bovine superoxide dismutase (9). We have focused our efforts on oxyhemocyanin and laccase.…”

mentioning

confidence: 99%

Magnetic susceptibility studies of laccase and oxyhemocyanin.

Dooley¹,

Scott²,

Ellinghaus³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

(1,2), and the oxidases laccase, ascorbate oxidase, and ceruloplasmin (3). Additionally cytochrome c oxidase has been proposed to contain a coupled heme ironcopper pair as the site of dioxygen binding and reduction (4). In no case has any electron paramagnetic resonance (EPR) signal attributable to a binuclear site been observed in the native protein (5). Although other structural possibilities are consistent with this observation, it is generally thought that the metal ions involved are strongly antiferromagnetically coupled, resulting in a diamagnetic or even spin ground state (5, 6). The temperature dependence of the magnetic susceptibility of such systems is distinctive and may be used to distinguish antiferromagnetic coupling from a truly diamagnetic structure-e.g., a Cu(I) dimer. For two antiferromagnetically coupled S = 1/2 Cu(II) ions, the susceptibility will be a maximum at a temperature that is simply related to the energy difference, J, between the diamagnetic ground state and the paramagnetic excited state (7). Antiferromagnetic coupling between two copper ions has been observed in a wide variety of dimeric Cu(II) complexes (8) and in the four-copper derivative of bovine superoxide dismutase (9). We have focused our efforts on oxyhemocyanin and laccase. It is generally accepted that the dioxygen binding site in oxyhemocyanin is a binuclear copper(II) peroxo complex, the evidence coming mainly from resonance Raman (10) and other spectroscopic (11,12) experiments. The four copper atoms in laccase are distributed in types 1 (paramagnetic), 2 (paramagnetic), and 3 (binuclear; EPR nondetectable) sites. The type 3 coppers apparently function as a two-electron acceptor and are thought to be the site of interaction with dioxygen (3).Previous magnetic susceptibility measurements showed oxyhemocyanin to be diamagnetic over the temperature range 35-250 K (13,14). Over this same range, the susceptibility of Rhus laccase showed, in addition to the Curie law paramagnetism of copper types 1 and 2, non-Curie paramagnetism at temperatures above 80 K that was consistent with an antiferromagnetically coupled Cu(II) pair with J = 170 ± 30 cm1 (13).Owing to the fact that the fit of theory to the observed deviation from Curie law in laccase was not entirely satisfactory (due in part to the low precision of the measurements) and realizing the importance of these observations to understanding the copper-site electronic structure of hemocyanin and laccase, we have remeasured the susceptibilities over a wider temperature range by using susceptometers recently developed at SHE Corporation, San Diego, CA. Although oxyhemocyanin was again observed to be essentially diamagnetic over the entire temperature range, laccase, in contrast to our previous results, displayed only the Curie law behavior of copper types 1 and 2 over the temperature range examined. MATERIALS AND METHODSRhus vernidfera laccase was purified by the method of Reinhammar (15) from the acetone powder (Saito & Co., Ltd., Japan) to a A2o/A614 value <15. A sample w...

show abstract

“…[1][2][3] There seems to be correlations between the magnetic properties of the systems and the dihedral angle between the bridging plane and the coordination square around copper, as well as with the Cu-O-Cu bridging angle. As a contribution of our previous work 4-7 on dimeric Cu complexes, this structure determination was performed to obtain more information about the stereochemistry around the copper atom.…”

mentioning

confidence: 99%

Crystal Structure of Dimeric [4-{(2-Oxybenzyl)imino}-2-penten-2-olato-O,O′,N]copper(II) Complex

et al. 1998

View full text Add to dashboard Cite

Due to the super exchange mechanism over the O atoms, dimeric copper(II) complexes with double oxygen bridges show subnormal magnetic moments. [1][2][3] There seems to be correlations between the magnetic properties of the systems and the dihedral angle between the bridging plane and the coordination square around copper, as well as with the Cu-O-Cu bridging angle. As a contribution of our previous work 4-7 on dimeric Cu complexes, this structure determination was performed to obtain more information about the stereochemistry around the copper atom.The crystalline ligand 4-[(2-hydroxybenzyl)imino]-2-hydroxy-2-penten was prepared from the mixture of 2-hydroxybenzylamine (1.23 g; 0.01 mol) and acetylacetone (1.0 g; 0.01 mol) in 30 ml of hot ethanol after 24 h in air. To a solution of the ligand (0.205 g; 1 mmol) in 40 ml DMF above 130˚C, a solution of Cu(CH 3 COO) 2 · H 2 O (0.199 g; 1 mmol) in 20 ml hot methanol was added dropwise and the mixture was set aside. The crystals were obtained after allowing the solution to stand for 36 h at room temperature. The chemical reaction of the title compound is shown in Fig. 1.The complex includes two Cu(C 12 H 13 NO 2 ) structure units linked via phenolic O atoms (Fig. 2)

show abstract

Copper(II) Complexes with Subnormal Magnetic Moments

Cited by 683 publications

References 88 publications

Etude par spectroscopie EXAFS au seuil K du cuivre des phases cristalline et colomnaire du stéarate de cuivre

Etude par spectroscopie EXAFS au seuil K du cuivre des phases cristalline et colomnaire du stéarate de cuivre

Magnetic susceptibility studies of laccase and oxyhemocyanin.

Crystal Structure of Dimeric [4-{(2-Oxybenzyl)imino}-2-penten-2-olato-O,O′,N]copper(II) Complex

Contact Info

Product

Resources

About