Sorption of Metal Carbonyl Complexes

Mononuclear metal carbonyls or small metal carbonyl dusters introduced into zeolite supercages, either by sorption or chemical vapor deposition, may react to form metal carbonyl clusters having nudearities (numbers of metal atoms) greater than those of the precursors. The resultant metal carbonyl dusters can be neutral or anionic, depending on the add-base properties and the degree of hydration of the zeolite. 

Similarly, the formation of [HFe3(CO)u] from [Fe3(CO)i2] sorbed in a NaY zeolite was postulated to result from a nucleophilic attack of OH on the coordinated CO ligand (Eq. 4.2). 

The formation of the anionic cluster was not observed in a dehydrated NaY zeolite, a result that indicates the importance of water or surface hydroxyl groups in the reaction. 

In contrast, Ballivet-Tkatchenko and Coudurier [51] reported that when [Fe3(CO)i2] in dehydrated HY zeolite was heated to 60 °C, [H2Fe3(CO)n] was formed within the supercages and interacted with the zeolite through hydrogen bonding. This difference in the behavior of the iron carbonyls in zeolite Y indicates the importance of the acid-base properties of the zeolite. 

4 Reductive Carbonylation of Mononuclear Metal Carbonyl Complexes 

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