Sharing the Burden of Reactivity: Synthesis, Characterization, and Reactivity of Phosphino-Alkoxide First-Row Transition Metal Complexes

Abstract

Bond activation is both central in many reaction mechanisms and essential to industrial production of chemicals. Many industries, such as pharmaceutical and petrochemical production, use precious metals to perform critical synthetic transformations that rely on bond activation. Due to the scarce nature of these precious metals, alternative approaches to bond activation have been sought. One such alternative approach is the polarization of covalent bonds of the substrate with earth-abundant catalysts. Through careful control of the ligand environment and metal selection, specific substrates can be targeted with precision. This dissertation describes the synthesis of complexes featuring earth-abundant 3d transition metals in monometallic complexes, bimetallic complexes, and frustrated Lewis pairs. Specifically, a phosphino-alkoxide ligand was developed to promote high-spin complex formation, produce unconventional geometries, and enable controlled dimerization. The complexes produced with this ligand were screened for bond activation capabilities, revealing activity for alkyne cyclotrimerization with certain monometallic complexes, both individually and in pairs. Overall, this work demonstrates the promise of earth-abundant 3d transition metal complexes as alternatives to precious metal catalysts for bond activation.