Tamizo Kogane

Structures and characterization of reaction products of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(ii) with 3-methyl- and 3,5-dimethyl-1h-pyrazoles

Abstract The reactions of [Cu(hfac)2] (Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) with 3-methyl- and 3,5-dimethyl-1 H-pyrazoles in light petroleum have been studied. These reactions give the 1 :2 adducts of [Cu(hfac)2(5-Hmpz)2] and [Cu(hfac)2(3,5-Hdmpz)2], respectively. The former adduct changes into complexes [Cu4(tfa)2(μ4-ttpt)2(5-Hmpz)4] (1a) and [Cu(hfac)(tfa)(5-Hmpz)2] (1b) (Htfa = trifluoroacetic acid; H3ttpt = 2,4,6-tris(trifluoromethyl) tetrahydropyran-2,4,6-triol; 5-Hmpz = 5-methyl-1H-pyrazole), while the latter does not change to give similar complexes. The crystal structures of { bd1a} and 1b have been determined. Complex 1a is tetranuclear, and four copper atoms linked together by two tridentate ttpt ligands are arranged in a parallelogram. The geometry about atoms Cu(1) and Cu(2) is distorted square-pyramidal, the coordination type being CuO5 and CuN2O3, respectively. Complex 1b is mononuclear and the geometry about the copper atom is a distorted tetragonal bipyramid. The axial positions are occupied by two oxygen atoms, one from a bidentate hfac ligand and the other from a monodentate tfa ligand. The two axial Cu-O distances are considerably different [2.294(7) and 2.522(6) , respectively] and the O(2)-Cu-O(3) axial bond angle is 162.0(2)°. The structures of 1:2 adducts are also discussed on the basis of IR and UV spectroscopy. Copyright

Magnetic Properties of 4- and 5-Methylpyrimidine-Bridged Copper(II) Complexes

Abstract The magnetic measurements of [L.Cu(hfac)2]n (L = 4- and 5-MPM, MPM = methylpyrimidine) revealed the presence of ferromagnetic interactions among Cu(II) spins. However, Cu spins in di- and trinuclear complexes were proved to be paramagnetic. The crystal structures of [4-MPM.Cu(hfac)2]n and (4- MPM)2.[Cu(hfac)2]3 were determined.

Characterization of reaction products of several bis(β-diketonato)copper(II) compounds with 1H-pyrazoles. Adducts, DI- and tetranuclear complexes, and coordination polymers

Abstract When [Cu(L 1 ) 2 ] (HL 1 = aliphatic β-diketone with branched alkyl groups) and [Cu(L 2 ) 2 ] (HL 2 =aliphatic β-diketone with linear alkyl groups) were allowed to react with 1H-pyrazoles (Hpzl), tetranuclear complexes [Cu 4 (μ 4 -O)(L 1 ) 4 (μ-pzl) 2 ] and dinuclear complexes [Cu 2 (L 2 ) 2 (μ-pzl) 2 ] were produced respectively, but the reactions of [Cu(L 3 2 ] (HL 3 = aroyl- or heteroaroylacetone) with 1H-pyrazole (Hpz) gave coordination polymers [{Cu(L 3 )(μ-pz)} n ] and/or adducts [Cu(L 2 ) 2 (Hpz) n ] ( n = 1 and/or 2). The substituent effects of the β-diketonato ligands on the reaction products are discussed. The structure of one of the tetranuclear products Cu 4 (μ 4 -O)(dibm) 4 (μ-4-mpz) 2 ] (Hdibm = 2,6-dimethylheptane3,5-dione; 4-Hmpz = 4-methyl-1 H-pyrazole) has been determined by X-ray analysis. The structures of some of the other products are estimated on the basis of their IR and diffuse reflectance spectra.

Double half-cubane copper(II) complexes available from copper(II) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate dissolved in formamides

Tetranuclear copper(II) complexes were obtained after simply dissolving [Cu(hfac)2] in formamide-methanol mixed solvents (Hhfac=1,1,1,5,5,5-hexafluoropentane-2,4-dione). X-Ray diffraction studies revealed that they possessed a tetranuclear double half-cubane core sandwiched with two trianionic ligands from 2,4,6-tris(trifluoromethyl)tetrahydropyran-2,4,6-triol (H3ttpt). Complexes [Cu4(ttpt)2(hfac)2(dmf)2.5], [Cu4(ttpt)2(tfa)2(def)4], and [Cu4(ttpt)2(hfac)2(H2O)4](fa) were prepared from N,N-dimethylformamide(dmf)-MeOH, N,N-diethylformamide (def)-MeOH, and formamide(fa)-MeOH (Htfa=trifluoroacetic acid), respectively. A possible mechanism is proposed where a templated aldol-type reaction takes place between hfac and 1,1,1-trifluoroacetonate. Magnetic measurements revealed the presence of antiferromagnetic interaction in the Cu4O6 core.

Preparation and characterisation of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(II) complexes with diazaaromatic compounds. Part 1. Crystal structures and characterisation of several adducts with diazines

The reactions of [Cu(hfac)2](Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) with diazines (tmpyz = 2,3,5-trimethylpyrazine, mpym = 5-methylpyrimidine and mpydz = 3-methylpyridazine) in light petroleum have been studied and the following complexes obtained: [{Cu(hfac)2}3(µ-tmpyz)2]1b, [Cu(hfac)2(tmpyz)]1e, [{Cu(hfac)2(µ-mpym)n}]2a, [{Cu(hfac)2}3(µ-mpym)2]2b, [{Cu(hfac)2}2(µ-mpym)]2c, [Cu(hfac)2(mpym)2]2d, and [Cu(hfac)2(mpydz)2]3d. The crystal structures of 1b, 2b and 3d have been determined. Although 1b and 2b are both trinuclear complexes with bridging diazole molecules, the geometry around atom Cu(2) is trigonal bipyramidal for 1b and tetragonal pyramidal for 2b. The geometry around atom Cu(1) is tetragonal bipyramidal in both complexes. The distance Cu(1)–N(1) is longer in 1b than in 2b, while the Cu(2)–N(2) is somewhat shorter in the former. The steric effects of the ligands on the structural differences between these complexes are discussed. On the basis of the relation between the geometry of the co-ordinated hfac ligands and ν(C–O) values, structures of some of the other complexes are suggested.

Existence and distribution of geometrical isomers of bis(VIC-dioximato)nickel(II) complexes in solution

The existence of geometrical isomers of several bis (vic-dioximato)nickel complexes with non-symmetrical ligands has been clarified by 1H NMR. The general formula of the ligands is CH3C(NOH)C(NOH)R, here R = Et, Prn, Bun, Ph, p-MeC6H4, p-MeOC6H4 and p-ClC6H4. The trans isomer of each complex is predominant in pyridine-d5 solution. The cis-trans equilibrium constants of these complex in pyridine-d5 have been estimated.

An electron spin resonance study on the interactions between bis-(pentane-2,4-dionato)copper(II) and some heterocycles. Part 2. The 1 : 1 adducts with aza-aromatic compounds and azacyclohexanes

E.s.r. spectra of a series of Cu(acac)2 adducts of aza-aromatic compounds and azacyclohexanes (L) were measured. The 1 : 1 adduct Cu(acac)2L is formed almost exclusively in chloroform solution, L occupying an apical site. Their g∥ and |A∥| values were determined in order to investigate the steric and electronic effects on co-ordination. When the frontal steric hindrance of the base is not large, the |A∥| values of Cu(acac)2L are linearly related to the pKa values of L. Since the nitrogen atoms in 2,6-dimethylpyridine, 2- and 8-methylquinoline, acridine, and N-methylazacyclohexanes have considerable frontal steric hindrance, remarkable deviations from the straight line are observed for these compounds. The presence of two 1 : 1 adducts is shown for N-methylmorpholine, the O-adduct being more favourable than the N-adduct because of steric hindrance.