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

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)(n)][AsF6](3). nMeCN (Ln = La, n = I; Ln = Sm, n = 3) show a nine-co-ordinate lanthanoid with a tricapped trigonal prismatic arrangement of N donor atoms. By reaction of LnCl(3) with AlCl3 in acetonitrile the complexes [Ln(MeCN)(9)][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.