Clusters naked

Cryophotochemical techniques have been developed that (i) allow a controlled synthetic approach to mini-metal clusters 112), Hi) have the potential for "tailor-making small, bimetallic clusters (mini-alloy surfaces) 114,116), Hi) permit the determination of relative extinction-coefficients for naked-metal clusters 149), and iv) allow naked-cluster, cryophotochemical experiments to be conducted in the range of just a few atoms or so 112,150,151). 

The copper system appears to behave similarly to the silver system, and it may be used here in order to illustrate the idea of "selective, naked-cluster cryophotochemistry 150,151). A typical series of optical-spectral traces that illustrate these effects for Cu atoms is given in Fig. 15, which shows the absorptions of isolated Cu atoms in the presence of small proportions of Cu2, and traces of Cus molecules. Under these concentration conditions, the outcome of 300-nm, narrow-band photoexcitation of atomic Cu is photoaggregation up to the Cus stage. The growth-decay behavior of the various cluster-absorptions allows unequivocal pinpointing of UV-visible, electronic transitions associated with Cuj and Cus 150). With the distribution of Cui,2,3 shown in Fig. 15, 370-nm, narrow-band excitation of Cu2 can be considered. Immediately apparent from these optical spectra is the growth (—10%) of the Cu atomic-resonance lines. Noticeable also is the concomitant... 

Corbett JD (1997) Diverse Naked Clusters of the Heavy Main-Group Elements. Electronic Regularities and Analogies. 87 157-194... 

The potential of naked cluster ions (416), for example Bi53+, for catalysis has been noted (35), but hydrogenations have not yet been reported. 

Table 4.4. Electron count for some typical naked clusters.

Teixidor F, Leutkens ML Jr, Rudolph RW (1983) Transition-metal insertion into naked cluster polyanions. J Am Chem Soc 105 149-150... 

The heavier elements of Group 13, in particular thallium, are able to form discrete naked clusters with alkali metals. Table 13.7.1 lists some examples of Tl - naked anion clusters, and Fig. 13.7.3 shows their structures. 

For example, B5H9 (nidoborane) has 14 skeletal bonding electrons. Wade s rules are applicable to "naked" clusters formed by / -block elements and so in case of [Pb5]2- having 22 valence electrons we expected 10 used lane pairs and 12 skeletal bonding electrons, i.e. a closo structure. 

Metal clusters in zeolites can be regarded as intermediate forms between the naked clusters and clusters which are stabilized chemically by a ligand shell. Fe and Co clusters with diameters of 4-11 A have been prepared from bis(toluol)metal complexes and NaY zeolite93 ). 

Cationic Naked Clusters of Bismuth Reduced Bismuth Halide Phases... 

Anionic Naked Clusters of Bismuth Zintl Ions... 

Net charge of the Si ion in the naked cluster (a) is 2.04 in comparison to the nominal -t-4 value embedding units drastically change the net Si charge. Thus, in cluster (b) the net Sic charge becomes 3.52, which is... 

---