Surface Organometallic Chemistry on Oxides: Reaction of Trimethylphosphine with Bis(allyl)rhodium Grafted onto Silica.
The reaction of Rh(eta(3)-C(3)H(5))(3) with the surface hydroxyl groups of partially dehydroxylated silica leads to the formation of the surface organometallic complex (&tbd1;SiO)(&tbd1;SiOX)Rh(eta(3)-C(3)H(5))(2), 1 (where X is H or Si&tbd1;), with evolution of propene. The reaction of 1 with PMe(3) was examined, and two major pathways were discovered. Reductive elimination of two allyl ligands as 1,5-hexadiene and coordination of PMe(3) give the surface product (&tbd1;SiO)Rh(PMe(3))(3), 2, which was characterized by elemental analysis, IR and (31)P MAS NMR spectroscopy. We also prepared 2 independently from CH(3)Rh(PMe(3))(3) and partially dehydroxylated silica. The second major reaction pathway is the elimination of propene to give (&tbd1;SiO)(2)Rh(eta(1)-C(3)H(5))(PMe(3))(3), 3. The presence of the sigma-bound allyl ligand was inferred from its characteristic IR spectrum. The reactivity of 3 toward CO was examined: insertion of CO into the Rh-C bond followed by reductive elimination of the silyl ester &tbd1;SiOC(O)C(3)H(5) produces (&tbd1;SiO)Rh(CO)(PMe(3))(2), 4. In static vacuum, 3 decomposes to give allyl alcohol, which is slowly decarbonylated by 2.
Scott
Susannah L.
SL
Laboratoire de chimie organométallique de surface, UMR CNRS-CPE 9986, Ecole Supérieure de Chimie-Physique-Electronique de Lyon, 43 blvd du 11 novembre 1918, 69616 Villeurbanne Cedex, France.
Dufour
Pascal
P
Santini
Catherine C.
CC
Basset
Jean-Marie
JM