SYNTHETIC ROUTES TO METAL ALKYLIDENE COMPLEXES THAT CATALYZE OLEFIN METATHESIS AND THE UTILIZATION OF [1.1.1]PROPELLANE AS A CARBENE PRECURSOR
Olefin metathesis is a class of reactions utilized in the fine-chemical and commodities industries. Homogenous catalysis of olefin metathesis can be performed by metal alkylidene species, and these compounds have been investigated for decades. In recent years, a focus has been placed on the development of catalysts using metals with lower toxicity and cost when compared to original systems utilizing ruthenium and molybdenum. The purpose of this work is to explore alternative routes towards the generation of metal alkylidene species with the goal of synthesizing first-row transition metal alkylidenes. To achieve this goal, pursuit of novel routes to generation masked alkylidenes was undertaken and new reactive small molecules were considered for use as alkylidene precursors. The study began with the synthesis of a library of PNP chelates of iron featuring various halide and alkyl ligands. The generation of masked alkylidene species through the utilization of a pendant amine group was unsuccessfully targeted by a variety of synthetic routes. [1.1.1]propellane was identified as a carbene precursor capable of generating stable metal alkylidene species with ruthenium, osmium, and vanadium. The reactivity of [1.1.1]propellane was investigated for a wide array of organometallic species and the scope was widened to include other propellane species, namely 1,3-dehydroadamantane. Efforts towards the synthesis of reduced titanium species with the goal of reaction with [1.1.1]propellane led to the identification of a number of interesting complexes and their reactivity was investigated in the final expansion of this work.