Alkaline-Earth Element Metallacarboranes

Recently, we have initiated an investigation of the chemistry of carboranes with alkaline-earth metals with a view to incorporate an alkaline-earth metal into a carborane cage. To date, there is no previous report of a discrete metallacarborane complex containing an aJkaline-earth metal in its structural framework. These molecules would be interesting from 

Rajesh Khattar, Mark J. Manning, and M. Frederick Hmihom 

Tile structure of 8 is illustrated in Fig. 3. The calcium atom asymmetrically caps the open hexagonal face of the nido-1ligand 

The molecular structure of 10 was established crystallographicalh. Suitable single crystals were grown from MeCN/EtjO at room temperature over a period of 3-4 days, mounted in a sealed glass capillary and the data were collected at room temperature. The crystal is composed of two crystallographically independent but structurally similar spiral chains. 

Three units of one of the spiral polymeric chains are shown in Fig. 4. A more detailed view of the metal-to-carborane interactions can be seen in p. j Each carborane fragment serves as a ligand to two strontium atoms. 

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Main Group Element Carborane Derivatives. Main group element carborane derivatives have been reviewed (231). Only a few alkaline-earth element metallacarborane derivatives have been characterized. The icosahedral beryllacarborane, f/ojo-3-[(CH3)3N]-3,l -BeC2B9H11, shown in Figure 24a, has been prepared via the reaction of /< -7,8-C2B9H13 and Be(CH3)2 [0(C2H3)2]2 followed by reaction of the diethyletherate product and trimethylamine (234). 

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