Structure of the solvated yttrium(III) ion in the oxygen donor solventsdimethyl sulfoxide, N,N-dimethylformamide and N,N′-dimethylpropyleneurea and crystal structures of [Y(OSMe2)8]I3 and [Y(OCN2Me2(CH2)3)6]I3

Abstract

The structure of the solvated yttrium(III) ion in the oxygen donor solvents dimethyl sulfoxide, N,N-dimethylformamide and N,N′-dimethylpropyleneurea, OCN₂Me₂(CH₂)₃, has been studied by means of XAFS and large angle X-ray scattering. The yttrium(III) ion co-ordinates eight solvent molecules in dimethyl sulfoxide and N,N-dimethylformamide solution with the mean Y–O bond distance 2.36(1) Å. The slightly asymmetric distribution was modelled by the cumulant expansion method for the XAFS data. The Y⋯S distance of the [Y(OSMe₂)₈]³⁺ ion in dimethyl sulfoxide solution was found to be 3.54(1) Å, corresponding to a mean Y–O–S angle of 132°. For the [Y(OCHNMe₂)₈]³⁺ ion in N,N-dimethylformamide the Y⋯C distance is 3.34(1) Å, giving a Y–O–C angle of 133°. In N,N′-dimethylpropyleneurea solution the steric effect of the bulky solvent molecules reduces the co-ordination number to six and the mean Y–O bond distance to 2.24(1) Å. The mean Y⋯C distance at 3.48(2) Å agrees with an analysis of the angular-sensitive multiple scattering contributions, which gave a Y–O–C angle of about 165°. The crystal structures of [Y(OCN₂Me₂(CH₂)₃)₆]I₃ and [Y(OSMe₂)₈]I₃, determined by X-ray diffraction at room temperature, show the ionic radii of yttrium(III) to increase about 0.12 Å from six to eight co-ordination.