Metal cluster fusion

Many novel cluster compounds have now been prepared in this way, including mixed metal clusters. Further routes involve the oxidative fusion of dicarbon metallacarborane anions to give dimetal tetracarbon clusters such as (103) and (104) O (jjg insertion of isonitriles into inetallaborane clusters to give monocarbon meiallacarboranes such as (105) and the reaction of small ii/t/o-carboranes with alane adducts such as Et3NAlH3 to give the commo species (106) ... 

Metal-promoted fusion or linkage of anionic CoC2B3 complexes affords exceedingly rich and varied chemistry. Thus, FeCl2-promoted oxidative face-to-face fusion gave Co2C4B6 clusters 62. With NiBr2, the product was a B-B... 

Note that the common fragment appears to be a 22 eve butterfly fragment (like B4H10) rather than a ring isoelectronic with C4H8. We will encounter this ambiguity for metal clusters as well when cluster fusion involves four common atoms. 

The preliminary studies described above indicate the power of combining molecular-beam techniques for synthesizing metal clusters of known size and composition and techniques for studying individual supported clusters. It is to be expected that this fusion of experimental methods will lead to increased understanding of the complex world of supported metal catalysts. 

For the charged-trimer emission, good agreement with the calculated fusion barriers of alkali metal clusters has been obtained by Garcias et al. [87], using the following parametrization of the bonding potential ... 

Combining the fusion-barrier calculated in this way with the heats of fission AHf (see Eq. 50) obtained from a classical metallic drop model, Garcias et al. obtained the fission barrier heights F for alkali metal clusters with charges... 

In the area of synthesis, the structural and theoretical framework contributed by Lipscomb provided a foundation for the monumental synthetic work of M. F. Hawthorne and his students, who transformed boron cluster chemistry first by their synthesis of the polyhedral borane anions BioHio and Bi2Hi2 (30) and later by the synthesis of metallacarboranes (31). In our own laboratory, considerations of charge distribution in borane anions (14) prompted us to explore reactions of transition metal ions with small borane and carborane anions (32). This, in turn, led to a number of advances including the first closed polyhedral metallaboranes (33), the discovery of metal-induced oxidative cage fusion (34), and the synthesis of B12H16, the only neutral Bi2 hydride, via metal-promoted fusion of BeHQ (35)... 

Of course, valence electron concentration is not only related to the metal atoms but also to the number and valence of the ligands. Ligand deficiency creates vacant coordination sites at metal atoms and results in cluster condensation, which is the fusion of clusters via short M-M contacts into larger units ranging from zero- to three-dimensional. The chemistry of metal-rich halides of rare earth metals comprises both principles, incorporation of interstitial atoms and cluster condensation, with a vast number of examples [22, 23]. 

Structurally, the E2M3 square pyramidal framework 45 is a fusion of two EM3 units (Scheme 1) that share the three metals. These compounds are summarized in Table XVI. Square pyramidal clusters with only one E... 

---