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Solvation Structure of Copper(II) Ion in N , N -Dimethylformamide and N , N -Dimethylformamide–Acetonitrile Mixtures Determined by the X-Ray Diffraction Method

1988; Oxford University Press; Volume: 61; Issue: 3 Linguagem: Inglês

10.1246/bcsj.61.945

1348-0634

Kazuhiko Ozutsumi, Shin‐ichi Ishiguro, Hitoshi Ohtaki,

Thermodynamic properties of mixtures

Abstract The solvation structure of copper(II) ion in N,N-dimethylformamide (DMF) and N,N-dimethylformamide–acetonitrile (AN) mixtures has been investigated by means of X-ray diffraction at 25 °C. The X-ray scattering data for the copper(II) perchlorate DMF solution were well-interpreted in terms of the presence of the axially elongated octahedral [Cu(dmf)6]2+ ion in DMF. Among the six DMF molecules, four of them are at the distance of 203(3) pm at the equatorial position and the other two are at 243(5) pm at the axial one. On the other hand, in copper(II) perchlorate DMF–AN solutions with the Cdmf⁄CCu mole ratios of 5.308 and 7.435, where Ci denotes the total concentrations of species i, the copper(II) ion is coordinated with four DMF molecules within the square-plane and with no solvent molecule along the axis of the plane. The equatorial Cu–O bond length is 200(1) pm and practically the same as that within the [Cu(dmf)6]2+ ion in DMF. In copper(II) nitrate DMF solutions (1.086 and 1.500 mol dm−3), a nitrate ion binds to copper(II) ion at the equatoral position and the distorted octahedral [CuNO3(dmf)5]+ complex is formed.