Tadashi Tokii

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

Abstract The magnetic properties over the temperature range from 80°–300°K are reported for a number of copper(II) complexes with N-hydroxyalkylsalicylideneimines having empirical formulae (A) Cu(Sal·N·ROH)X and (B) Cu(Sal·N·RO), where Sal·N = · ·C 6 H 4 · H = N·, ROH = CH 2 CH 2 OH, CH 2 CH(CH 3 )OH, C(CH 3 ) 2 CH 2 OH and CH 2 CH 2 CH 2 OH, and X = Cl − , NO 3− and ClO 4− . Their magnetic properties differ depending upon the attached anion X or the R group. Of the (A) type of complexes, Cu(Sal·N·CH 2 CH 2 OH)Cl, Cu(Sal·N·CH 2 CH 2 OH)ClO 4 ·H 2 O and Cu(Sal·N·CH 2 CH(CH 3 )OH) ClO 4 ·C 2 H 5 OH exhibited antiferromagnetic behavior conforming to the Bleaney-Bowers equation, while the other complexes showed normal paramagnetic properties. For the (B) type of complexes, Cu(Sal·N·CH 2 CH 2 CH 2 O) exhibited antiferromagnetic behavior typical of binuclear copper(II) complexes, whereas the other complexes had ferromagnetic properties. The diffuse reflectance and i.r. spectra of these complexes have been measured in order to obtain information about their structure.

Stereochemistries of three types of bi-nuclear copper(II) chloride complexes with N-substituted salicylideneimines☆

The preparation of some bi-nuclear copper(II) chloride complexes with N-substituted salicylideneimines, [Cu(O2.C6H4.(5X|5).C1H − R)Cl]2, where R = alkyl, substituted phenyl groups and (CH2)3OH; and X = H, Cl, CH3 and NO2; and some addition compounds of these with two moles of dimethylformamide (DMF) and dimethylsulfoxide (DMSO) per one dimeric molecule are reported. Measurements of magnetic moments at room temperatures or for some of them temperature variations of magnetic susceptibilities over a temperature range 76°–320°K, reflection spectra at 2000–2340 mμ, and i.r. spectra in rock salt region were recorded for these complexes. These complexes are classified into three types of different stereochemistries based on color and reflection spectra: (1) B-type, brown in color, pseudo-tetrahedral; (2) YG-type, yellow-green, square pyramidal; and (3) Y-type yellow-orange, trigonal-bipyramidal. The empirical rule, “higher energies of d-d bands — lower magnetic moments”, was valid in the B-type complexes. For the Y-type complexes, the existence of electronegative atom or groups seems to be required.

Magnetic and spectral studies on copper(II) halide complexes with N-ethanolsalicylideneimines☆

Abstract In order to investigate which structural factors cause the antiferromagnetic behavior in copper(II) chloride complexes with N-ethanolsalicylideneimine Cu(Sal·N·EtOH)Cl, where SaI·N·EtOH = · O 2 ·C 6 H 4 · C 1 H = N·CH 2 CH 2 OH , the magnetic and spectral properties of a series of copper(II) halide complexes with N-ethanol-5-substituted-salicylideneimines, (H, CH3, Cl and NO2), have been studied. On the basis of their magnetic, i.r. and diffuse reflectance spectral data, we have assigned a chloride-bridged binuclear structure for Cu(Sal·N·EtOH)Cl and Cu(5-CH3·Sal·N·EtOH)Cl, a phenolic oxygen-bridged binuclear structure for Cu(5-CH3·Sal·N·EtOH)-Br·0·1DMF and a phenolic oxygen-bridged linear trimetric structure for Cu3(Sal·N·EtOH)2Cl4·2C2H5OH, where 5CH 3 ·Sal=· O 2 ( C 5 H 3 )·C 6 H 3 · C 1 H= and DMF = N,N-dimethylformamide. Cu2(5-CH3·Sal·N·EtOH)Cl3·0·5H2O exhibited a higher polymeric behavior of antiferromagnetism. All the other complexes obeyed the Curie-Weiss law with very small Weiss constants, θ ≅ −2 ∼ 6°K.

Antiferromagnetism induced by successive protonation of terminal phenol groups of a bis(μ-phenoxide)-bridged dicopper(II,II) complex

The reaction of a tripodal ligand (H2L = N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine) with Cu(NO3)2·3H2O and Cu(ClO4)2·6H2O in methanol yielded [Cu2(HL)2](NO3)2·H2O (1) and [Cu2(HL)2](ClO4)2 (1′), respectively. When H2L was allowed to react with CuSO4·5H2O in the presence of triethylamine (1 ∶ 1 ∶ 2) in methanol, the neutral dicopper(II,II) complex [Cu2(L)2] (2) was obtained. The monopositive species [Cu2(L)(HL)]ClO4·CH3OH·H2O (3) crystallized on mixing 1′ and 2 (1 ∶ 1) in methanol–dichloromethane. The crystal structures of 1, 2, and 3 were determined by X-ray crystallography. All of the complexes consist of a discrete dinuclear molecule with bis(μ-phenoxide)-bridges. The tripodal ligand functions as a tetradentate ligand and one of the phenolic oxygen atoms serves as a bridging ligand. Protonation/deprotonation takes place at the terminal phenol moiety and as the phenol group is deprotonated the coordination geometry changes from a distorted square pyramid to a distorted trigonal bipyramid. The two copper ions in 1–3 are antiferromagnetically coupled with 2J = −714 (1), −19.9 (2), and −277 cm−1 (3). The results clearly demonstrate that protonation/deprotonation causes a change in coordination geometry, which in turn drastically affects magnetic exchange interactions.

Synthesis and crystal structure of a novel hexanuclear Zr(IV) complex with 1,10-phenanthroline including carboxylato, hydroxo, and oxo bridging

Abstract A novel hexanuclear Zr(IV) complex, [Zr 6 (O) 6 (OH) 2 (Ph 2 CHCOO) 10 (phen) 2 ]·4CH 3 CN ( 1 ), where phen denotes 1,10-phenanthroline, has been prepared and characterized on the basis of elemental analysis, infrared-spectroscopy measurements, and X-ray crystallography. Complex 1 resides on a crystallographic inversion center, thus making only three of the six zirconium ions unique. The six zirconium ions are arranged in apices of an octahedron. One Zr(IV) metal ion (Zr1) is individually joined with two Zr(IV) metal ions (Zr2, Zr3) by one syn–syn bridging carboxylate group, and Zr1 has three μ 3 -O and one μ 3 -OH bridges through Zr2 and Zr3. The Zr2 atom is also connected by one syn–syn bridging carboxylate group through Zr3*. Moreover, Zr1 is coordinated by two nitrogen atoms of a bidentate 1,10-phenanthroline group with eight coordination. Besides these, Zr2 is coordinated by one carboxylate of a bidentate–chelate type, completing the eight coordination. The Zr3 atom is coordinated by one monodentate carboxylate oxygen, consequently has a novel seven coordination.

Magneto-Structural Correlations in Dimeric Copper(II) Carboxylates

Abstract For dimeric copper(II) carboxylates, the most important factor determining the strength of the spin superexchange interactions is the electronic structure of the carboxylato bridge. It also has been revealed that the trigonal bipyramidal deformation of the coordination geometry around the copper atoms, and the bending of the carboxylato bridge decrease the antiferromag-netic interactions.

Synthesis, structure, and characterization of dicopper(II) complex with a new amidate ligand

Abstract The dicopper(II) complex, (NBu4)2[Cu2(L3-H)2] (1), with a new terdentate ONO-ligand (H3L3-H) containing amide nitrogen has been prepared. X-ray crystallographic analysis reveals that the complex has a di-μ-alkoxo-bridged dicopper(II) structure. Magnetic measurements for 1 indicate that a strong antiferromagnetic interaction is operative in the dicopper core with −2J value of 750 cm−1. Cyclic voltammograms of 1 showed irreversible oxidation waves at +0.62 and +0.88 V which was assigned as metal centered oxidations.

Dimeric nickel(II) carboxylates and a silanecarboxylate: [Ni(Me3CCOO)2(2,5-lutidine)]2, [Ni(MePh2CCOO)2(quinoline)]2.2CHCl3, [Ni(Me2PhCCOO)2(quinoline)]2, [Ni(Me3CCOO)2(2-ethylpyridine)]2, [Ni(Me3CCOO)2(2-picoline)]2 and [Ni(MePh2SiCOO)2(Ph3P)]2

Determination structurale de six complexes dimeriques du nickel dont cinq ont un coordinat carboxylate et un a un coordinat silanecarboxylate. Geometrie pyramidale carree autour du nickel. La partie Ni 2 [COO] 4 forme une structure cage legerement deformee. Les distances Ni...Ni sont dans la gamme 2.7079-2.765A

DNA promotes the activation of oxygen molecules by binuclear cobalt(II) compounds

Abstract We have observed that binuclear cobalt(II) compounds with H(HPTP), Co2(HPTP)(CH3COO)(ClO4)2 and Co2(HPTP)Cl(ClO4)2, react with oxygen molecules when DNA is present in the solution, cleaving the DNA (H(HPTP) denotes N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,3-diaminopropane-2- ol).

Cleavage of the C-N bond of a peptide group by a copper(II)-peroxide adduct with an η1-coordination mode

Abstract We have obtained clear evidence that a copper(II)-peroxide adduct with an η1-coordination mode can cleave the C–N bond of a peptide group and hydroxylate the alkyl group nearby; this may provide helpful information for elucidation of the reaction mechanism of PAM, peptidylglycine α-amidating monooxygenase.