- THE REACTION OF SCANDIUM TRIFLUORIDE WITH CYCLOPENTADIENYL SALTS AND THE CRYSTAL AND MOLECULAR STRUCTURE OF THE TRIMER OF FLUORODICYCLOPENTADIENYLSCANDIUM
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The reaction of ScF3 with (C5H5)2Mg gives a mixture of (C5H5)3Sc and (η-C5H5)2ScF, not pure (C5H5)3Sc as reported previously.The same mixture is obtained on treating ScF3 with C5H5Na in tetrahydrofuran.The two products can be separated since (η-C5H5)2ScF is soluble in toluene whereas (C5H5)3Sc is not .The structure of (η-C5H5)2ScF shows it to be trimeric with a planar (Sc-F)3 ring (average Sc-F distance 2.046(8) Angstroem, F-Sc-F and Sc-F-Sc angles 86.5(3) and 153.4(4) degree, respectively).Crystal data: monoclinic, Cc, a 17.019(8), b 15.273(7), c 10.359(8) Angstroem, β 92.33(5) degree, Z = 4; Mo-Kα radiation, R = 0.076 for 1238 observed reflection and 325 variables.
- Bottomley, Frank,Paez, Daniel E.,White, Peter S.
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- Multinuclear magnetic resonance study of tris(cyclopentadienyl)scandium: A fluxional dimer with bridging cyclopentadienyl groups
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(C5H5)3Sc is known to be associated via bridging cyclopentadienyl groups in the solid state, but hitherto nothing was known as to the nature of the compound in solution. 1H NMR studies of the compound in THF show that it exhibits two fluxional processes. The first process observed on cooling is an exchange between the π and σ-bonded rings. The second process, which can only be slowed and not completely stopped on the NMR time scale, is a metallotropic 1,5-shift of the Cp2Sc moiety around the σ-bonded cyclopentadienyl ligand. The existence of only one species in THF, over the temperature range +30 to -80°C is shown by 45Sc NMR. In toluene, however, the exchange between σ and π-bonded cyclopentadienyl ligands is complicated by the onset of dimer formation via bridging cyclopentadienyl groups at low temperature. The presence of two different scandium environments at low temperature is shown by variable-temperature 45Sc NMR spectra.
- Bougeard, Peter,Mancini, Mary,Sayer, Brian G.,McGlinchey, Michael J.
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