Carboranes properties

Synthesis and properties of carborane-containing organophosphorus compounds 97UK1125. 

Polyary lsiloxanes Carboranes Good thermal stability 400-500°C (752-932°F) coatings, adhesives Stable in air and nitrogen at 400-450°C (752-842°F) elastomeric properties for silane derivatives up to 538°C (1000°F) adhesives. 

Quite a number of silylnickel and silylenenickel compounds have been reported, and only a few can be cited here2305-2309 Bis(silyl)nickel complexes have been implicated as important intermediates in Ni-catalyzed double silylation of various organic substrates. Using an o-bis(dimethylsilyl)carborane ligand, complex (930) could be isolated and structurally characterized 2310 Its unusual thermal stability is attributed to the advantageous steric and electronic properties of the carboranyl unit. (930) undergoes... 

The first examples of DNA metallointercalators containing a 1,2- or 1,7-carborane thiolato ligand have been reported.349 For example, treatment of [Pt(OTf)(terpy)]+ (terpy = 2,2 6, 2 -terpyr-idine) with l-HSCH2-l,2-C2B10Hii leads to the formation of [Pt(l-SCH2-l,2-C2BioHn)(terpy)]+ (143). The DNA-binding properties of several complexes have also been described. 

The preparation of poly(m-carborane-siloxane) polymers has also been successfully achieved directly from the carborane monomer.22 The reaction used is shown in scheme 9. Here, the direct salt elimination reaction between dilithiocarborane and a dichlorosiloxane (e.g., 1,5-dichlorohexamethyltrisiloxane) results in the formation of linear polymers with a molecular-weight (M ) typically of 6800 dalton. However, the reported literature detailing this approach is very limited indeed, and the reaction has not found significant use. This is most probably because only relatively low molecular-weight polymers can be produced, ultimately restricting the flexibility to produce materials of controlled mechanical properties. 

At AWE, the Lewis acid-catalyzed bulk polymerization route has been the main synthesis route to poly(m-carborane-siloxane) elastomers. Our selection has been based on considerations of safety, availability of key reagents, and ease of scale-up operations. An understanding of the physical and chemical properties of these materials, and how these properties can be modified through the synthesis process, is essential in order to develop materials of controlled characteristics. 

BNCT sensitisers are designed with neutron capture in mind, but those that are porphyrin/ phthalocyanine-based may show PDT activity. An example is the disodium (or dipotassium) salt of the tetrakis-carborane ester (58) derived from 3,8-bis(l,2-dihydroxyethyl)deuteroporphyrin.298 This is water soluble and tumor selective, showing high tumor/normal brain ratios.299 Photophysical properties are similar to other water-soluble porphyrins in rat glioma cells, specific localization in mitochondria is observed.300... 

The selective basic degradation of 1,2-dicarbaclovodode-carborane(12) and its C-methyl and C-phenyl derivatives has been recently reported.3 The ethanolic potassium hydroxide degradation of C, C"-dimethyl-l, 2-dicarbaclovododecaborane (12) and the isolation of the trimethylammonium salt of the resulting B9C2Hio(CH3)2 anion are described here as an illustration of this general reaction. The properties of the trimethylam-... 

Building on and extending earlier studies, Schleyer, Najafian, et al. [57] employed computed geometric, energetic, and magnetic properties to quantify the aromaticity of the closo boranes B H 2 (6 < n < 12), and their isoelectronic counterparts, the CB iH and C2B 2H carboranes, and the NB H azaboranes [34]. All possible heteroatom placements were considered. The most stable iso-... 

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