Trivalent scandium, yttrium and lanthanide complexes with thia-oxa and selena-oxa macrocycles and crown ether coordination

Abstract

Complexes of the oxa-thia macrocycles [18]aneO₄S₂, [15]aneO₃S₂ and the oxa-selena macrocycle [18]aneO₄Se₂ (L) of types [MCl₂(L)]FeCl₄ (M = Sc or Y) were prepared from [ScCl₃(thf)₃] or [YCl₂(THF)₅][YCl₄(THF)₂] and the ligand in anhydrous MeCN, using FeCl₃ as a chloride abstractor. The [MI₂(L)]I, [LaI₃(L)] and [LuI₂(L)]I have been prepared from the ligands and the appropriate anhydrous metal triiodide in MeCN. Complexes of type [LaI₃(crown)] and [LuI₂(crown)]I (crown = 18-crown-6, 15-crown-5) were made for comparison. Use of the metal iodide results in complexes with high solubility compared to the corresponding chlorides, although also with increased sensitivity to moisture. All complexes were characterised by microanalysis, IR, ¹H, ⁴⁵Sc and ⁷⁷Se NMR spectroscopy as appropriate. X-ray crystal structures are reported for [ScCl₂([18]aneO₄S₂)][FeCl₄], [ScI₂([18]aneO₄S₂)]I, [YCl₂(18-crown-6)]₃[Y₂Cl₉], [YCl₂([18]aneO₄S₂)][FeCl₄], [LaI₃(15-crown-5)], [LaI₂(18-crown-6)(MeCN)]I, [LuI(18-crown-6)(MeCN)₂]I₂, [Lu(15-crown-5)(MeCN)₂(OH₂)]I₃, [LaI₃([18]aneO₄S₂)], [LaI([18]aneO₄S₂)(OH₂)]I_2, [LaI₃([18]aneO₄Se₂)] and [LuI₂([18]aneO₄Se₂)]I. In each complex all the neutral donor atoms of the macrocycles are coordinated to the metal centre, showing very rare examples of these oxophilic metal centres coordinated to thioether groups, and the first examples of coordinated selenoether donors. In some cases MeCN or adventitious water displaces halide ligands, but not the S/Se donors from La or Lu complexes. A complex of the oxa-tellura macrocycle [18]aneO₄Te₂, [ScCl₂([18]aneO₄Te₂)][FeCl₄] was isolated, but is unstable in MeCN solution, depositing elemental Te. YCl₃ and 18-crown-6 produced [YCl₂(18-crown-6)]₃[Y₂Cl₉], the asymmetric unit of which contains two cations with a trans-YCl₂ arrangement and a third with a cis-YCl₂ group.