Part 1. Surface organometallic chemistry and catalysis involving cyclopentadienyltricarbonyltungstate(1-) on magnesium oxide, aluminum oxide and zinc oxide. Part 2. Characterization of platinum mordenite catalysts for N-hexane hydrocracking/isomerization

Deprotonation of (HCpW(CO){dollar}sb3{dollar}) (Cp = C{dollar}sb5{dollar}H{dollar}sb5){dollar} by adsorption on MgO, {dollar}gamma{dollar}-Al{dollar}sb2{dollar}O{dollar}sb3,{dollar} K/Al{dollar}sb2{dollar}O{dollar}sb3,{dollar} and ZnO yields surface-bound (CpW(CO){dollar}sb3{dollar}) {dollar}sp-.{dollar} On metal oxide surfaces containing hard Lewis acid centers (e.g., K{dollar}sp+,{dollar} Mg{dollar}sp{lcub}2+{rcub},{dollar} and Al{dollar}sp{lcub}3+{rcub}),{dollar} (CpW(CO){dollar}sb3{dollar}) {dollar}sp-{dollar} forms adducts with {dollar}{lcub}{dollar}M{dollar}sp{lcub}rm n+{rcub}{rcub}{dollar} via {dollar}Sigma{dollar}-CO-isocarbonyl ligands, as evidenced by {dollar}nusb{lcub}rm CO{rcub}{dollar} infrared and extended X-ray absorption fine structure (EXAFS) spectroscopies. A novel bis (isocarbonyl) (CpW(CO){dollar}sb3{dollar}) {dollar}sp-{dollar} species is formed on highly dehydroxylated {dollar}gamma{dollar}-Al{dollar}sb2{dollar}O{dollar}sb3{dollar} surfaces. A simple relationship is observed between the CO stretching force constant of the isocarbonyl ligand(s) and the electrostatic potential (n{dollar}sp+{dollar}/r{dollar}sb+){dollar} of {dollar}{lcub}{dollar}M{dollar}sp{lcub}rm n+{rcub}{rcub}.{dollar} On ZnO, the infrared spectrum of surface-bound (CpW(CO){dollar}sb3{dollar}) {dollar}sp-{dollar} is consistent with W-Zn bond formation, paralleling the chemistry of (CpW(CO){dollar}sb3{dollar}) {dollar}sp-{dollar} with soft Lewis acid centers (e.g., transition metals) in solution. Surface-bound (CpW(CO){dollar}sb3{dollar}) {dollar}sp-{dollar} on {dollar}gamma{dollar}-Al{dollar}sb2{dollar}O{dollar}sb3{dollar} was the precursor of a stable propene metathesis catalyst.; The structure of Pt clusters hosted in hydrogen-mordenite (HM) was investigated by in situ X-ray absorption spectroscopy, H{dollar}sb2{dollar} temperature-programmed desorption (H{dollar}sb2{dollar} TPD), and infrared spectroscopy of adsorbed CO. EXAFS spectroscopy evidenced a Pt cluster size of 5-7 atoms after reduction of Pt(II)-M in H{dollar}sb2{dollar} at 350 or 450{dollar}spcirc{dollar}C. A low-Z contribution to the EXAFS spectrum of Pt/HM catalysts reduced at 450{dollar}spcirc{dollar}C in H{dollar}sb2{dollar} was assigned to Al (or Si) atoms at 2.4 A. This metal-support interaction was associated with a suppression of H{dollar}sb2{dollar} chemisorption by the intrazeolitic Pt clusters, as evidenced by H{dollar}sb2{dollar} TPD. XANES spectra contained a feature at 10 eV beyond the Pt L{dollar}sb{lcub}rm III{rcub}{dollar} edge that was assigned to adsorbed H{dollar}sb2{dollar} on the basis of in vacuo H{dollar}sb2{dollar} desorption experiments. The {dollar}nusb{lcub}rm CO{rcub}{dollar} infrared spectrum of CO adsorbed on the Pt clusters had a strong band at 2085 cm{dollar}sp{lcub}1{rcub}{dollar} that was assigned to linear CO on Pt, and smaller bands at 1870 and 2124 cm{dollar}sp{lcub}-1{rcub}{dollar} that were assigned to bridging CO on Pt and CO on isolated Pt centers, respectively.; Normal-hexane hydrocracking/isomerization was used as a test reaction to probe the active sites of Pt/M catalysts. For Pt/HM pretreated in H{dollar}sb2{dollar} at 350{dollar}spcirc{dollar}C, the formation of C{dollar}sb6{dollar} isomerization products at 240-300{dollar}spcirc{dollar}C appeared to be diffusionally limited, as the apparent activation energies (14-16 kcal/mol) are lower than that expected for isomerization via a bifunctional mechanism. Pretreatment of Pt/HM at 450{dollar}spcirc{dollar}C suppressed metal-catalyzed reactions (dehydrocyclization and hydrogenolysis). (Abstract shortened by UMI.)...