PREPARATION AND X-RAY CRYSTAL-STRUCTURES OF TETRAHYDROFURAN-COMPLEXEDRARE-EARTH CHLORIDES - A STRUCTURALLY RICH SERIES

Anhydrous lanthanoid metal chlorides LnCl(3)(thf)(N) (Ln = La, Ce, Nd, Sm, n = 2; Ln = Tb, Ho, n = 2.5; Ln = Dy, Tm, n = 2.7; Ln = Gd, Yb, L u, n = 3; Ln = Er, n = 3.5) have been prepared in excellent yield by t he direct reaction of the lanthanoid metal powders with hexachloroetha ne in tetrahydrofuran (thf), and (Ln = Eu, n = 0.8; Ln = La, n = 1.7; Ln = Pr, n = 2; Ln = Gd: n = 2.5; Ln = Er, n = 3) in good yield except for EuCl3(thf)(0.8) from bulk metal. [YbCL3(thf)(2)](2) was prepared by prolonged treatment of solid YbCl3(thf)(3) with pentane. The X-ray crystal structures of [LnCl(3)(thf)(2)] (Ln = La, Ce or Pr), [LnCL(3)( thf)(3.5)] (Ln = Gd or Er), [YbCl3(thf)(3)] and [LaCl3(thf)(H2O)] have been determined. For [LaCl3(thf)(2)], a square antiprismatic single-s tranded polymer, ...La(mu-Cl)(3)(thf)(2)La(mu-Cl)(3)(thf)(2)..., is th e first eight-coordinate LnCl(3)(thf)(n) complex. The metal is surroun ded by two sets of three bridging chlorines and cis thf oxygens. [LnCl (3)(thf)(2)] (Ln = Ce, Pr) have seven-coordinate structures with doubl y chloride-bridged linear chains, ...LnCl(mu-Cl)(2)(thf)(2)LnCl(mu-Cl) (2)(thf)(2)... where the lanthanoid atom exists in a pentagonal bipyra midal environment, the pentagonal bipyramidal plane being defined by f our chloride atoms and one oxygen atom of the thf ligand, and the axia l positions being occupied by a chloride and a thf oxygen atom. [LnCl( 3)(thf)(3.5)] (Ln = Gd, Er) crystallize as discrete ion pairs, [LnCl(2 )(thf)(5)](+)[LnCl(4)(thf)(2)](-). The lanthanoid atom in the cation d isplays pentagonal bipyramidal geometry with two apical chloride atoms and five equatorial thf ligands while the anion has quasi-regular oct ahedral stereochemistry with trans thf ligands. [LaCl3(thf)(H2O)] disp lays an eight-coordinate two-dimensional polymeric array with six brid ging chlorides per lanthanum atom. Far-infrared spectra have been reco rded for a number of products and used as a basis for structural propo sals, particularly for products with fractional thf.