Main Group Elements Supported by pi-Conjugated, Nitrogen-Rich Ligand Frameworks and the Catalytic Formation of Guanidines

Abstract

This thesis investigated the structure and reactivity of group 13 elements boron, aluminum and gallium supported by nitrogen rich ligand systems. The majority of this work deals with N,N',N"-trisubstituted guanidinate ligands and N,N'-disubstituted-1,8-diaminonaphthalene dianionic ligand frameworks. New methods for the catalytic formation of guanidines have also been explored. Chapter 1 outlines the basics of using nitrogen rich compounds as ligands. This includes the introduction of guanidinates as supporting ligands and the description of using a rigid backbone system such as an N,N'-disubstituted-1,8-diaminonaphthalene dianionic ligand. Chapter 2 presents the synthetic routes taken to form a variety of aluminum amide, alkyl and halide complexes using N, N',N"-trisubstituted triisopropyl guanidinates as supporting ligands. The formation of dinuclear guanidinate species was also observed. Chapter 3 investigates the catalytic formation of guanidines using inexpensive, commercially available aluminum compounds as catalysts for the guanylation of various amines with carbodiimide. A full catalytic cycle was calculated using DFT studies for both guanylation of amines and phosphines catalyzed by aluminum amides. Chapter 4 presents the application of N,N'-disubstituted-1,8-diaminonaphthalene ligands for the stabilization of coordinately unsaturated group 13 elements. The formation of boron halides with both diaryl and diisopropyl 1,8-diaminonaphthalene ligands as well as aluminum halides and a dinuclear aluminum complex is presented.