Chini clusters

When the irradiation of metal ion solutions is performed in the presence of the ligands CO or PPhs, metal reduction, ligandation, and aggregation reactions compete, leading to reduced metal complexes and then to stable molecular clusters, such as Chini clusters Pt3(CO)6] with m = 3-10 (i.e., 9-30 Pt atoms) [97], or other metal clusters [98]. The synthesis is selective and m is controlled by adjusting the dose m decreases at high doses). The mechanism of the reduction has been determined recently by pulse radiolysis [99]. Molecular clusters [Pt3(CO)6]5 have been observed by STM [100]. 

Figure 8. Transmission electron micrograph of Pt nanoparticles prepared by the controlled removal of CO at 573 K for 5 h from the Chini cluster anion [Pt3(CO)6]5 synthesized in FSM-16. The nanostnictured particles (15-20 nm diameter) were uniformly aligned in the ordered channels of FSM-16 (28 A).

Figure 9. Templating fabrication of Pt nanoparticles prepared by the controlled removal of CO from the Chini cluster anions [Pt3(CO)6]n (n = 5,6) synthesized in FSM-16, and the Pt nanowires by the exposure of H2PtCl6/FSM-16 with 2-propanol and water to y-rays or UV-light.

The closed metal carbonyl clusters. P. Chini, Inorg. Chim. Acta, Rev., 1968, 2,31-51 (223). 

For a summary of synthetic work on large saturated clusters see E. L. Muetterties, Chemical and Engineering News, 30 Aug. 1982, pp. 28-42. Also P. Chini, J. Organometal. Chem. 200, 37 (1980). 

The mechanism for ether formation is quite simple given the recent work of Chini (19) that shows that rhodium clusters can react to give strong acids ... 

Contents P. Chini, B. T. Heaton Tetranuclear Carbonyl Clusters. 

Such a strong analogy between the electronic behavior of the metallic core of large molecular clusters and small metal particles was already suspected by Basset, Primet et al., who had discovered already in 1975 [21] that the extent of back donation from the core of a metal particle to [NO] (a ligand isoelectronic to CO) adsorbed Pt/alumina catalyst was particle size dependent as if the small particles were behaving as molecular clusters, since the extent of back donation on coordinated CO was shown clearly to be dependent on the size of the cluster in the series of molecular [PtsCCOJ j]" (n = 1-5, etc.) clusters made by Chini s group [22]. 

I am pleased to acknowledge many fruitful discussions of cluster chemistry with several cluster chemists, particularly Professor P. Chini and Drs. A. J. Banister and R. E. Williams. 

CHINI ET al. Carbonyl Hydride Clusters and Interstial Hydrides... 

The chemistry of the carbidocarbonyl clusters of cobalt and rhodium (none is known for iridium) is predominantly the work of Italian school of the late Paolo Chini and colleagues. The first rhodium cluster of this type to be reported was [Rh6C(CO)ls]2, 24 (59), isolated as a minor by-product in the synthesis of [Rh7(CO)t6]3- (and originally misformulated as [Rh3(CO)l0]-). The formation of 24 resulted from the reaction of [Rh7(CO)l6]3- with chloroform (the source of the carbon atom), present as an impurity in the reaction solvent, and 24 is now synthesized by this reaction [Eq. (17)]. 

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