title: Grafting of [Mn(CH2tBu)2(tmeda)] on silica and comparison with its reaction with a silsesquioxane.
abstract: The reaction of [Mn(CH2tBu)2(tmeda)] (1) and a silica partially dehydroxylated at 700 degrees C (SiO(2/700)) yields a single surface species [([triple bond]SiO)Mn(CH2tBu)(tmeda)] (2a; tmeda = tetramethylethylendiamine), while a mixture of 2a and [([triple bond]SiO)2Mn(tmeda)] (2b) is obtained by using SiO(2/200), SiO(2/300), or SiO(2/500) as evidenced by mass balance analysis, and IR and EPR spectroscopy. The reaction of 1 and (c-C5H9)7Si7O12SiOH (3), a soluble silanol that is a molecular model for a silica support, generates the bis-siloxy complex 4, [[(c-C5H9)7Si7O12SiO]2Mn(tmeda)2], in a quantitative yield; compound 4 was characterized by single-crystal X-ray diffraction. These reactions exemplify the limitation of considering molecular silanol derivatives as straightforward and reliable homogeneous models for silica, and address the need for thorough characterization of surface species by the use of surface-science techniques. These studies show the possibility of preparing coordinatively and geometrically unique surface species that would be difficult to prepare by solution chemistry methods; insights into the chemical and physical properties of these surface species are also gained.
authors.affiliation: Laboratoire de Chimie Organométallique de Surface, UMR 9986 CNRS-CPE Lyon, CPE Lyon, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne Cedex, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Riollet
authors.forename: Elsje Alessandra
authors.initials: EA
authors.lastname: Quadrelli
authors.forename: Christophe
authors.initials: C
authors.lastname: Copéret
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Basset
authors.forename: Richard A
authors.initials: RA
authors.lastname: Andersen
authors.forename: Klaus
authors.initials: K
authors.lastname: Köhler
authors.forename: Rolf-Michael
authors.initials: RM
authors.lastname: Böttcher
authors.forename: Eberhardt
authors.initials: E
authors.lastname: Herdtweck