title: Grafting of peralkylated Ln(II)Al(III) heterobimetallic complexes onto periodic mesoporous silica KIT-6.
abstract: Tetraethylaluminates of the divalent lanthanides ytterbium and samarium were grafted onto large-pore cubic periodic mesoporous silica (PMS) KIT-6, which had been dehydroxylated at 500 degrees C (specific surface area a(s): 500 m(2)g(-1); mesopore volume V(p): 1.06 cm(3)g(-1); main pore diameter: 85 A). The bimetallic materials [Ln(AlEt(4))(2)]@KIT-6(-500) were analysed by DRIFT spectroscopy, elemental analysis, nitrogen physisorption and solid-state NMR. Upon heterogenization the surface area and pore volume of the KIT-6 materials dropped by 30-35% and 25%, respectively. The hybrid materials were compared to AlEt(3)@KIT-6(-500) since reaction of AlEt(3) with surface silanol groups is also a prominent reaction pathway when complexes [Ln(AlEt(4))(2)](n) are immobilized. Reaction of the Ln(II) tetraalkylaluminates with tris(tert-butoxy)silanol HOSi(OtBu)(3) gave complexes Ln[(mu-OSi(OtBu)(3))(mu-R)AlR(2)](2) (Ln = Yb, Sm; R = Et; Ln = Yb; R = Me) which can be seen as molecular model complexes, evidencing alkane elimination, trialkylaluminium adduct formation, and Ln(II)-O(siloxane) bonding.
authors.affiliation: Department of Chemistry, University of Bergen, Allégaten 41, 5007, Bergen, Norway.
authors.forename: Erwan
authors.initials: E
authors.lastname: Le Roux
authors.forename: Olaf
authors.initials: O
authors.lastname: Michel
authors.forename: Hanne-Marthe
authors.initials: HM
authors.lastname: Sommerfeldt
authors.forename: Yucang
authors.initials: Y
authors.lastname: Liang
authors.forename: Cäcilia
authors.initials: C
authors.lastname: Maichle-Mössmer
authors.forename: Karl W
authors.initials: KW
authors.lastname: Törnroos
authors.forename: Reiner
authors.initials: R
authors.lastname: Anwander