Syntheses and structures of some homoleptic acetonitrile lanthanoid(III) complexes

Abstract

From the reaction of [{Ln(SO₂)_n(AsF₆)₃}_x] (Ln = La or Sm) with acetonitrile the complexes [Ln(MeCN)₉][AsF₆]₃ have been prepared. The crystal structures of [Ln(MeCN)₉][AsF₆]₃·nMeCN (Ln = La, n = l; Ln = Sm, n = 3) show a nine-co-ordinate lanthanoid with a tricapped trigonal prismatic arrangement of N donor atoms. By reaction of LnCl₃ with AlCl₃ in acetonitrile the complexes [Ln(MeCN)_n][AlCl₄]₃ (Ln = Pr, n = 9; Ln = Yb, n = 8) have been synthesized, and they have also been prepared very simply by the reaction of the lanthanoid metal, AlCl₃, and C₂Cl₆ in acetonitrile. The crystal structure of [Pr(MeCN)₉][AlCl₄]₃·MeCN shows nine-co-ordinate praseodymium also with a tricapped trigonal prismatic arrangement of N donor atoms, whilst [Yb(MeCN)₈][AlCl₄]₃ has square dodecahedral YbN₈ eight-co-ordination.