Synthesis of chromium guanidinate complexes and their activity in ethylene oligomerizationpolymerization

Abstract

The overall objective in this body of work was to synthesize a new class of chromium complexes containing a bound guanidinate ligand (Chapter 2) and ultimately test these complexes for catalytic activity in ethylene oligomerization/polymerization reactions (Chapter 4). A number of reactions between the chromium guanidinate complexes and alkyl aluminum reagents (Chapter 3) were attempted to gain insight into the nature of the active species in the catalytic cycle. A large majority of the complexes presented in this thesis have been characterized using x-ray crystallography. Additionally a number of dimeric CrII complexes were obtained with bridging guanidinate and alkyl groups. One such complex had an ultra short CrII-Cr II distance of 1.773 A (Steven Horvath, Serge I. Gorelsky, Sandro Gambarotta, Ilia Korobkov Angew. Chem 2008, 47, 9937) and a thorough DFT study was performed on the complex (Chapter 3). The catalytic testing of this new class of chromium guanidinate complexes was very promising and a thorough investigation of the factors that affect the selectivity and activity of the catalysts was performed (Chapter 4).