The surface reactivity of Ir4(CO)12 supported on silica has been investigated by means of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed decomposition techniques. The initial stage of physisorption from a solution results in the deposition of large crystallites (φ > 2μ) of Ir 4(CO)12, unevenly distributed on the surface. By thermal treatment in vacuum at 100°C the complete sublimation of Ir 4(CO)12 occurs. By heating under Ar or O2 at 100°C a disaggregation of the crystallites to single Ir4(CO) 12 units evenly distributed on the surface is observed. Admission of water vapour at 25°C promotes a high surface mobility of the Ir 4(CO)12 units towards reaggregation. The formation of metallic particles is achieved by thermal decomposition of well dispersed Ir4(CO)12 in Ar at 150-200°C or at lower temperatures in H2. The adsorption of CO at 100°C leads to disruption of large metallic particles. This surface process is enhanced by a preliminary study under O2 at 25°C.

SURFACE ORGANOMETALLIC CHEMISTRY - PHYSISORPTION AND THERMAL-DECOMPOSITION OF IR4(CO)12 ON SILICA / R. PSARO, C. DOSSI, A. FUSI, R. DELLAPERGOLA, L. GARLASCHELLI, D. ROBERTO, L. SORDELLI, R. UGO, R. ZANONI. - In: JOURNAL OF THE CHEMICAL SOCIETY. FARADAY TRANSACTIONS. - ISSN 0956-5000. - 88:3(1992), pp. 369-376.

SURFACE ORGANOMETALLIC CHEMISTRY - PHYSISORPTION AND THERMAL-DECOMPOSITION OF IR4(CO)12 ON SILICA

R. PSARO;A. FUSI;L. GARLASCHELLI;D. ROBERTO;R. UGO;
1992

Abstract

The surface reactivity of Ir4(CO)12 supported on silica has been investigated by means of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed decomposition techniques. The initial stage of physisorption from a solution results in the deposition of large crystallites (φ > 2μ) of Ir 4(CO)12, unevenly distributed on the surface. By thermal treatment in vacuum at 100°C the complete sublimation of Ir 4(CO)12 occurs. By heating under Ar or O2 at 100°C a disaggregation of the crystallites to single Ir4(CO) 12 units evenly distributed on the surface is observed. Admission of water vapour at 25°C promotes a high surface mobility of the Ir 4(CO)12 units towards reaggregation. The formation of metallic particles is achieved by thermal decomposition of well dispersed Ir4(CO)12 in Ar at 150-200°C or at lower temperatures in H2. The adsorption of CO at 100°C leads to disruption of large metallic particles. This surface process is enhanced by a preliminary study under O2 at 25°C.
Settore CHIM/03 - Chimica Generale e Inorganica
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/194177
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