Decomposition of Metal Carbonyl Clusters

Researchers have attempted to drive off the carbonyl ligands of molecular metal carbonyl clusters in the hope of preparing naked clusters of the same nuclearity. It is now evident, although this assertion contradicts some of the claims in the literature, that most of the attempts have failed and have instead led to increases in cluster nuclearity and loss of structural simplicity. Usually, the lack of sufficient characterization has prohibited the determination of the nudearities of all the resultant spedes, and often only the larger spedes (dusters) have been detected. With the increasing availability of techniques such as high resolution transmission electron microscopy and EXAFS spectroscopy this field is expected to develop rapidly. 

Similarly, [Rh6(CO)i6] in NaY zeolite has been decarbonylated. [65, 126] It was observed that the decarbonylation was reversible, which suggests that the decarbonylated spedes were Rh i. However, this suggestion is speculative as will be discussed below. Rao et al. [65] showed that [Rh6(CO)j4] in NaY zeolite could be 

Nagy et al. [127] used thermal decomposition of [Fe(CO)s] sorbed in HY zeolite to form highly dispersed iron partides, which were observed by transmission electron microscopy to be 10-50 A in size. Photodiemical decomposition gave smaller partides (too small to be observed with transmission electron micros-copy), presumaUy because of the strong interaction between the carbonyl dusters and the surface resulting from the eledronic exdtation of the metal carbonyl during decomposition. 

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