Steric modification of beta-diketiminato ligands on low valent chromium towards a better model of ethylene trimerization

Theopold, KlausThis thesis describes an extension of the research conducted on low valent β-diketiminato chromium compounds. The main thrust of this work is the significant increase of steric bulk on the known 2,4 Pentane-N,N’-bis(2,6-diisopropylphenyl) ketiminato (Dipp-NacNac) ligand by the addition of a triphenylmethyl substituent at the 4- position of the phenyl rings. This has the effect of nearly doubling the ligand's mass and significantly increasing its size, with the result that the metal complexes with this ligand show signs of steric effects seeming to play a more significant role in their formation than in complexes of the parent system. Unfortunately, complexes of this ligand tend to suffer from solubility issues, making them somewhat difficult to work with. Although the goal of ethylene trimerization with a monomeric Cr (I) ethylene complex has not been achieved, this work points to possible promising lines of inquiry in the form of easily modified trityl derivatives.University of Delaware, Department of Chemistry and BiochemistryM.S