The Synthesis of Linear and Nonlinear Photosensitive Organometallic Polymers Containing Mo-Mo Bonds: Evaluating the Effectiveness of Click Chemistry
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This dissertation details the use of click chemistry to prepare linear and nonlinear polymers containing metal-metal bonds. The incorporation of metal-metal bonds into the polymer simplfies the degradation mechanism, allowing fundamental mechanistic studies of polymer degradation. Click chemistry offered a brand new route to explore the preparation of these useful but intricate metal-metal bond-containing polymers. Chapter I discusses the utility of these types of polymers for mechanistic studies, the preparation of metal dimers with reactive functionalities, and the previous polymerization methods which have been explored. The need for a new polymerization strategy, such as click chemistry, is described. Chapter II explains the preparation of a new metal dimer click synthon, [(η5-C5H4(CH2)3OC(O)(CH2)2C≡CH)Mo(CO)3]2, and the necessary conditions needed to polymerize the synthon using click chemistry. A high molecular weight linear polymer was prepared, suggesting click chemistry is a viable route to nonlinear polymers. Chapter III presents a second novel metal dimer click synthon, [(η5-C5H4(CH2)3N3Mo(CO)3]2, and attempts to use click chemistry to prepare a star polymer containing metal-metal bonds. A small amount of nonlinear polymer was prepared but several reactivity problems were also discovered and addressed. Due to these problems with click chemistry, Chapter IV details a brand new method for preparing asymmetric metal dimers. CpMo(CO)3-Mo(CO)3Cp(CH2)3CH=CH2 is the first reported example of an asymmetric dimer, and (CH3)3CSi(CH3)2O(CH2)3CpMo(CO)3-Mo(CO)3Cp(CH2)3OC(CH3)2OCH3 is the first example of a bifunctional asymmetric dimer. Chapter V describes the synthesis of a different type of metal dimer, (CH3)2Si[(C5H5)Mo(CO)3]2, which is polymerized by thermal ring opening polymerization. The dimer did not polymerize as expected and yielded an interesting polymer which has both Mo-Mo single bonds and Mo≡Mo triple bonds. Finally, Chapter VI provides a summary of the work as well as an honest perspective of using click chemistry to prepare metal-metal bond-containing polymers. This dissertation includes previously published and unpublished co-authored material.