UC Riverside

ABSTRACT OF THE DISSERTATION

Neutral and Anionic Carboranes as Electronically and Sterically Diverse Phosphine Substituents

by

Christopher Alexander Lugo

Doctor of Philosophy, Graduate Program in Chemistry

University of California, Riverside, June 2017

Dr. Vincent Lavallo, Chairperson

The chemistry of carboranes has expanded greatly since their discovery in the 1960’s. Displaying 3D aromaticity, superior thermal and chemical stability, and facile tunability, these molecules have seen a wide range of applications but little has been said for their potential as transition metal catalysts. We sought to remedy this rift by 1) constructing a library of ligands that integrate carboranes into phosphines as R-group substituents, 2) ligating the ligands to an array of transition metal centers, and 3) surveying the reactivity of the isolated metal complexes.

By substituting the inherently bulky ortho-carborane with a terphenyl moiety at the C-2 position, and a phosphine at the C-1 position, a massive ligand was created. The donor and steric properties were analyzed via a rhodium carbonyl complex. A nido version of the above terphenyl carboranyl phosphine was also synthesized and its behavior with iridium was investigated. Through preparation of phosphines of the anionic 12 and 10-vertex carboranes, rhodium carbonyl complexes were synthesized to quantitatively assess their donor properties. Through utilization of a carboranylphosphino iron complex, the ability to cyclically trimerize methylacrylate has been demonstrated through the isolation a phosphonium enolate species. Amongst the vast library of monoanionic carboranyl phosphines there are none containing a dianionic phosphine. Using PCl3 as a launch pad, a variety of monoanionic and dianionic ligands were systematically prepared with ranging electronic and steric profiles.