Characterization and photochemistry of surface-confined mononuclear and trinuclear phosphine/carbonyl complexes of ruthenium(0)

The characterization and photochemistry of (SiO/sub 2/)-L3Ru3(CO)/sub 4/ and (SiO/sub 2/)-LRu(CO)/sub 9/ are reported, where (SiO/sub 2/)-represents high surface area (approx.400 m/sup 2//g) SiO/sub 2/. Synthesis of (SiO/sub 2/)-LRu(CO)/sub 4/ and (SiO/sub 2/)-L/sub 3/Ru/sub 3/(CO)/sub 9/ is effected by reaction of Ru(CO)/sub 4/(PPh/sub 2/CH/sub 22/Si(OEt)/sub 3/) or Ru/sub 3/(CO)/sub 9/(PPh/sub 2/CH/sub 2/CH/sub 2/Si(OEt)/sub 3/)/sub 3/ with a hydrocarbon suspension of (SiO/sub 2/)-. Solid-state /sup 13/C, /sup 29/Si, and /sup 31/P CP/MAS NMR, Fourier transform, UV-vis photoacoustic spectroscopy, and elemental analyses establish the nature of the functionalized (SiO/sub 2/-. Typical coverage of -LRu(CO)/sub 4/ or -L/sub 3/Ru/sub 3/(CO)/sub 9/ is approx. 10/sup 10/-10/sup -11/ mol/cm/sup 2/. Photoexcitation (near-UV) of (SiO/sub 2/)-LRu(CO)/sub 4/ suspended in hydrocarbon media results in a chemical reaction consistent with the dissociative loss of CO to give a 16-valence-electron, surface-confined species that reacts with 2-electron P-donors. The light-induced extrusion of CO can be effected and detected spectroscopically by chemical trapping in rigid media at low temperature (approx.90K). Near-UV irradiation of (SiO/sub 2/-LRu(CO)/sub 4/ at 298 K exposed to a gas gives chemistry consistent with dissociative loss of CO also. Complete (>90%) exchange of CO for /sup 13/CO can be effected by irradiation under 1 atm of /sup 13/CO,more » as monitored by FTIR/photoacoustic spectroscopy. The photochemistry of (SiO/sub 2/-L/sub 3/Ru/sub 3/(CO)/sub 9/ involves metal-metal bond rupture; under 1 atm of CO in a solid gas reaction or as a suspension in hydrocarbon solvent saturated with CO, (SiO/sub 2/)-L/sub 3/Ru/sub 3/(CO)/sub 9/ yields (SiO/sub 2/)-(LRu(CO)/sub 4/)/sub 3/. The Ru-P bond is photo-inert. 10 figures, 2 tables.« less