3-CENTER OXIDATIVE ADDITION OF PHOSPHORUS YLIDES TO RU3(CO)12

Phosphorus ylides undergo oxidative addition to Ru3(CO)12 to yield a wide range of RU3 clusters with triply bridging organic ligands derived from the ylides. Ph3P = CH2 forms HRu3(CO)9(mu3-Ph3P-CH-CO) (1) containing a phosphonio enolate. Ph3P = CH - CHO yields a product mixture containing the phosphonio enolate-bridged cluster and its PPh3 derivative 6, the phosphoniomethylidyne-bridged compound H2Ru3(CO)9(mu3-C-PPh3) (5), and the ketenylidene-bridged compound H2Ru3(CO)8(PPh3)(mu3-C-CO) (7). Thermal treatment converts the phosphonio enolate ligand (in 1) into the phosphoniomethylidyne ligand (in 5), and the latter into the ketenylidene ligand (in 7). With Ph3P = CH-C(O)Me and Ru3(CO)12 ortho-metalated Ru3 derivatives 10, 11 of the phosphonio ketone R3P-C-C(O)Me are produced, and likewise with Ph3P = CH-COOEt the ortho-metalated derivative 12 of the phosphonio ester R3P-C-CO2Et. Me3P = CH-COOtBu is oxidatively added to form HRu3(CO)9(mu3-Me3P-C-COOtBu) (13) bearing a phosphonio ester ligand. - The crystal structures of 6 and 13 are reported. The sequence of Ru3 clusters and the bonding modes of the mu3 ligands can be related to the surface reactions during Fischer-Tropsch catalysis.