Metallic derivatives of carboranes

Metal derivatives of carboranes. The last group of metal compounds to be mentioned here are those in which one or more carborane ions are rr-bonded to a transition-metal atom to form either a composite ion or a neutral molecule. Examples are shown in the self-explanatory Fig. 24.25, namely, the ions [Co(B9C2Hi 1)2] and [B9C2H1 iRe(CO)3] both studied in their Cs salts,... 

The material reviewed in this Chapter hitherto has focused on metallacarboranes in which the metal atom is a vertex in an icosahedral cage framework. Until recently, monocarbollide metal compounds with core structures other than 12 vertexes were very rare since suitable carborane precursors were not readily available." However, Brellochs recent development of the reaction of decaborane with aldehydes to give 10-vertex monocarboranes permits a considerable expansion in this area of boron cluster chemistry. As a consequence, several intermediate-sized monocarboranes are now easily accessible and we have recently begun to exploit the opportunities that these present. In particular, we have focused thus far on complexes derived from the C-phenyl-substituted species [6-Ph- zJo-6-CBgHii] It is clear from these initial studies that a wealth of new chemistry remains to be discovered in this area, not only from among the metal derivatives of PhCBg car-boranes such as those discussed in this section, but also in the metal complexes of other newly available carboranes. 

The preparation of a series of transition-metal derivatives of monocarbon carborane anions of the type BioHioCNHs, ... 

Metallorganic carborane polymers are synthesized by reaction of group-IV organo-metallic dihalides with dialkali-metal derivatives of meta- and para-carboranes . ... 

A particularly elegant route to metallacarbor-anes is the direct oxidative insertion of a metal centre into a c/oso-carborane cluster the reaction uses zero-valent derivatives of Ni, Pd and Pt in a concerted process which involves a nett transfer of electrons from the nucleophilic metal centre to the cage ... 

Cyclopentadienyl derivatives of ruthenium were first complexes of this metal which were found to be able to catalyze ATRP 1, 7-10). Subsequently carborane (11-12) and alkylidene (13) rathenium complexes were employed as ATRP catalysts. 

Organometallic group 13 species investigated for non-linear optics are essentially limited to derivatives of the metalloid element, boron. A number of different organoboron systems have been used in NLO chromophores. We have described the use of 77-boratobenzene transition metal derivatives as acceptors in Section 12.04.1.2.2.(iii) and 12.04.1.2.2.(iv). In this section, we will discuss three-coordinate boranes, four-coordinate borates, and finally carboranes. 

---