Grafted organometallic fragments

Simultaneous measurements of both the amount of butane evolved and the quantity of grafted organometallic fragments at increasing time of reaction allows the stoichiometry of the surface complexes Pts[SnBux] / to be determined (Fig. 7). Furthermore, extrapolation to a low amount of Sn grafted shows that a [BusSnJ Pts species is formed, which then rapidly evolved towards more dealkylated species and finally to Pts[SnBu]jy. 

The reaction proceeds selectively on the host metal surface by successive hydrogenolysis of the Sn-R bonds with evolution of the corresponding saturated hydrocarbons (R-H). There is a formation of partially dealkylated grafted organometallic fragments (Equation (1)). 

Figure 2.14 Schematic representation of the various stages of the grafting of a surface organo-tin complex on a platinum particle (as demonstrated by EXAFS, NMR, chemical analysis, IR). From left to right starting platinum particle with the surface organometallic fragment [(Pts)3(Tl -snBu]i adatoms of Sn, [(Pt4(ri -Sn]) surface PtSn alloy [sphere color-code orange (Pt), blue (H), white (C), green (Sn)].

Organometallic derivatives of polyoxometalates are perfectly characterized at the molecular level and in turn provide models for the grafting of an organometallic catalyst on an oxide surface, especially in the case of the supported derivatives. Beyond, they also display their own reactivity and catalytic activity.Some synergy between the organometallic and oxide parts has been reported in the literature, as well as bifunctional activity. The mobility of organometallic fragments at an oxide surface could also be reproduced on a polyanion. 

At low temperature, there is less than 1.5 Ce evolved by reacted AsPhs on the NiD18 sample and the coverage of the metallic surface does not exceed 1 (table 3). We can conclude that there is formation of grafted surface organometallic fragments which can be formulated as Nis(AsPhx)y. 

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