title: Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties.
abstract: This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect.
authors.affiliation: Chemisches Institut der Otto-von-Guericke-Universität Magdeburg , Universitätsplatz 2, 39106 Magdeburg, Germany.
authors.forename: Janek
authors.initials: J
authors.lastname: Rausch
authors.forename: Volker
authors.initials: V
authors.lastname: Lorenz
authors.forename: Cristian G
authors.initials: CG
authors.lastname: Hrib
authors.forename: Vanessa
authors.initials: V
authors.lastname: Frettlöh
authors.forename: Matthias
authors.initials: M
authors.lastname: Adlung
authors.forename: Claudia
authors.initials: C
authors.lastname: Wickleder
authors.forename: Liane
authors.initials: L
authors.lastname: Hilfert
authors.forename: Peter G
authors.initials: PG
authors.lastname: Jones
authors.forename: Frank T
authors.initials: FT
authors.lastname: Edelmann