Microwave promoted iodination of anionic borate and carborate clusters
Graham R. Matheson
May 13, 2015
Department or Program
Boron and carborane clusters are promising starting materials for a variety of applications such as weakly coordinating anions, superacidic catalysts and medical imaging agents. Heavily iodinated cages are excellent candidates for X-ray contrast agents because of their low toxicity, metabolic inactivity and high molecular weight ratio of iodine. However, functionalization of these cages has significant synthetic challenges because of their relatively low-reactivity. Known protocols for synthesis of these molecules requires heating for up to 3 days the use of expensive, caustic reagents. In this work, CB₁₁I₆H₆⁽⁻⁾, CHB₁₁I₁₁⁽⁻⁾ and B₁₂I₁₂⁽²⁻⁾ were all prepared in a microwave irradiation (MWI) reactor with improved yields, shorter times of reaction, and less hazardous reaction conditions. Hexabromination of CB₁₁H₁₂⁽⁻¹⁾ and the attempted conjugate acid synthesis of CB₁₁H₆I₆⁽⁻¹⁾ are reported as well. This thesis discusses the natural history of the element boron, reviewing its cosmic origins, historical and modern applications and interesting chemical properties. Special attention is paid to the synthesis and characterization of heavily iodinated cluster compounds.