| Abstract
| - The reactivity (e.g., toward hydrolysis, alcoholysis, reduction by CO or H2) of [Os3(CO)10(μ-H)(μ-OSiPh2R‘)] (R‘ = Ph, OH, OSiPh2OH) species and the thermal behavior of [Os3(CO)10(μ-H)(μ-OSiEt3)] are reported, clarifying by a molecular approach some aspects of the surface chemistry of [Os3(CO)10(μ-H)(μ-OSi⋮)]. By this approach, molecular models are not only tools to define structural aspects but also springboards to understand the molecular aspects of the reactivity of organometallic species on the silica surface.
- The reactivity (e.g., toward hydrolysis, alcoholysis, reduction by CO or H2) of various [Os3(CO)10(μ-H)(μ-OSiPh2R‘)] (R‘ = Ph, OH, OSiPh2OH) clusters and the thermal behavior of[Os3(CO)10(μ-H)(μ-OSiEt3)] have been studied with the aim of clarifying by a molecularapproach some aspects of the surface chemistry of silica-anchored [Os3(CO)10(μ-H)(μ-OSi⋮)].Their easy and selective reduction to [Os3(CO)12] (under CO) and to [H4Os4(CO)12] (underH2) suggests that [Os3(CO)10(μ-H)(μ-OSi⋮)] does not require, as a reactive intermediate, aprevious hydrolysis to the more reactive molecular species [Os3(CO)10(μ-H)(μ-OH)] in orderto generate different osmium carbonyl clusters in their silica-mediated synthesis startingfrom OsCl3 or [Os(CO)3Cl2]2. The thermal behavior of [Os3(CO)10(μ-H)(μ-OSiEt3)] dissolvedin triethylsilanol (to mimic a silica surface with many available surface silanols) or triglyme(to mimic a highly dehydroxylated silica surface) gives an answer to the controversy on thenature of the products formed by thermal degradation on the silica surface of [Os3(CO)10(μ-H)(μ-OSi⋮)]. In triethylsilanol, oxidation occurs to give a Os(II) hydrido carbonyl specieswhich, on the basis of chemical and spectroscopic evidence, we suggest to be [Os(CO)3(μ-OSiEt3)2(OSiEt3)(H)Os(CO)2]n (n = probably 2), whereas in triglyme an aggregation to high-nuclearity clusters such as [H4Os10(CO)24]2- and [H5Os10(CO)24]- occurs. Therefore, it is shownfor the first time that molecular models not only are a tool to define structural aspects butalso may be a springboard to understand and clarify by a molecular approach aspects of thereactivity of organometallic species on the silica surface.
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