The mononuclear and dinuclear dimethoxyethane adducts of lanthanide trichlorides [LnCl3(DME)2]n, n = 1 or 2, fundamental starting materials in lanthanide chemistry: preparation and structures

ABSTRACT Some new dimethoxyethane (DME) adducts of lanthanide trichlorides of formula [LnCl3(DME)2]n, n=1 or 2; (n=2, Ln=La, Ce, Pr, Nd; n=1, Ln=Eu, Tb, Ho, Tm, Lu) have been prepared by treating Ln2O3, or LnCl3 · nH2O, or Ln2(CO3)3, in DME as medium, with thionyl chloride at room temperature, eventually in the presence of water in the case of Ln2O3 and Ln2(CO3)3. The complexes from lanthanum to praseodymium included are chloro-bridged dimers. In the case of neodymium, the new results complement the literature data, showing that both the mononuclear and dinuclear species exist: neodymium can therefore be regarded as the turning element from dinuclear to mononuclear structures along the series. Only mononuclear complexes were isolated in the Eu–Lu sequence. The lanthanide contraction has been evaluated on the basis of the Ln–O and Ln–Cl bond distances on the isotypical series of the mononuclear complexes LnCl3(DME)2 covering a range of 12 atomic numbers.