Synthesis and Crystal Structure of π-Aromatic Chloroaluminate Complexes of Samarium(II) (η6-Arene)Sm(AlCl4)2•nC6H6 and Na[(η6-Arene)Sm(AlCl4)3]•C6H6 (Arene = C6H6 or C6H3Me3)

Samarium(II) pi-aromatic chloroaluminate complexes (eta(6)-C(6)H(6))Sm(AlCl(4))(2)center dot 0.5C(6)H(6) (I), (eta(6)-C(6)H(3)Me(3))Sm(AlCl(4))(2) (II), Na[(eta(6)-C(6)H(6))Sm(AlCl(4))(3)]center dot C(6)H(6) (III), and Na[(eta(6)-C(6)H(3)Me(3))Sm(AlCl(4))(3)]center dot C(6)H(6) (IV) were prepared by reducing SmCl(3) with sodium amalgam (I -IV), metallic aluminum (II), orsamarium (II) in the presence of AlCl(3) and an aromatic ligand. Single-crystal X-ray diffraction analysis showed that the Sm atom in complexes I-IV has a pentagonal-bipyramidal environment comprised of the pi-aromatic ligand and six Cl atoms. The structures of I and II are polymeric: the neighboring complexes are joined by the bridging Cl atoms (Sm-Cl-Al) to form infinite layers (I) or chains (II). Structures III and IV contain the [(eta(6)-C(6)H(6)) Sm(AlCl(4))(3)]-anions and the Na(+) cations weakly bound to them. The average distancesare the following: Sm-Cl 3.02 angstrom, Sm-C 3.03 angstrom, and Na center dot center dot center dot Cl (III and IV) 2.89 angstrom. The structures of the Sm(II) complexes are compared with those of the Yb(II) and Ln(III) pi-aromatic complexes.