Synthesis and characterisation of η6-arene (halogenidoaluminato)-lanthanoid(II) and alkaline earth(II) complexes

eta(6)-Arene(iodidoaluminato)lanthanoid(II) complexes, {[Ln(eta(6)-C6H5Me)(AlI4)(2)]}(n) [Ln = Sm, 1, Eu, 2, Yb, 3; C6H5Me = toluene] have been prepared by reactions of in situ generated aluminium triiodide with the corresponding lanthanoid metals and 1,2-diiodoethane in toluene (molar ratio: 2:1:1). Compounds 1-3 are polymeric and the lanthanoid(II) atom of 1 and 2 is coordinated by an eta(6)-arene and three chelating kappa (I, I') tetraiodidoaluminate ligands, two of which are also bridging (LnI(2)AlI(2)Ln) and one is terminal. 3 is coordinated by an eta(6)-arene, one terminal chelating kappa (I, I') and one chelating and bridging (YbI2AlI2Yb) tetraiodidoaluminate ligand, and one monodentate tetraiodidoaluminate ligand, which is also bridging (YbIAl(I)I2Yb). These are the first X-ray crystal structures of arene(tetrakisiodidoaluminato)lanthanoid(II) complexes. The first reported alkaline earth(II) (eta(6)-arene)iodidoaluminate complexes, namely [Ca(eta(6)-C6H5Me)(AlI4)(2)](n) (4), {[Sr(eta(6)-C(6)H5Me)(AlI4)(2)](n)middotnPhMe} (5), [Ba(eta(6)-C6H5Me)(2)(AlI4)(2)] (6), [Ca(eta(6)-C6H3Me3-1,3,5)(AlI4)(2)](n) (7) and {[Sr(eta(6)-C6H3Me3-1,3,5)(AlI4)(2)](n)middot0.5n(PhMe3)} (8) have also been obtained in an arene (toluene or mesitylene) solution by a similar method. Complex 4 is isocoordinate with 3, and 5 is isomorphous with 2. Complex 7 has eight coordinate Ca similar to 4, and complex 8 has nine coordinate Sr as in 5. Mononuclear ten coordinate complex 6 is the first example of a monomeric eta(6)-arene sandwich complex of barium. The Eu-II bromidoaluminate complex {[Eu(eta(6)-C6H5Me)(AlBr4)(2)](n)middot0.5nPhMe} (9) has been prepared from Eu metal, AlBr3, and BrCH2CH2Br in toluene and has a unit cell similar to 8 despite the different metal and arene.

Automated summary

Eta(6)-arene(iodidoaluminato)lanthanoid(II) complexes have been synthesized by reacting aluminum triiodide, corresponding lanthanoid metals, and 1,2-diiodoethane in toluene. These complexes are polymeric and the coordination modes of the lanthanoid(II) atoms vary. Alkaline earth(II) (eta(6)-arene)iodidoaluminate complexes have also been obtained using a similar method. The crystal structures of these complexes have been determined for the first time.