Adsorption and decomposition of Mo(CO)6 in zeolite NaY

The adsorption and decomposition of Mo(CO)6 in zeolite NaY has been examined gravimetrically and spectroscopically. Saturation adsorption at room temperature is 2.1 Mo(CO)6 per zeolite supercage. Subsequent heating in vacuo at 373 K causes loss of two carbonyl ligands per molybdenum which can be reversed by addition of CO. Heating at or above 473 K causes complete and irreversible decarbonylation, producing zero-valent molybdenum within the zeolite structure. Further uptake of Mo(CO)6 occurs on subsequent exposure to the vapour at room temperature; zeolites containing up to 157 Mo per unit cell have been prepared by repeated adsorption and decomposition cycles.