Disubstituted 1,8-diaminonaphthalene as supporting ligands for high oxidation state early transition metal and lanthanide complexes

Abstract

This work was launched to study the chemistry of disubstituted 1,8-diaminonaphthalene (R2DAN) as a supporting framework for carbene centers, high oxidation state early transition metals and lanthanide centers. R2DAN ligands are dianionic bidentate groups making them good candidates to stabilize high oxidation state complexes. This work focuses on the preparation of early transition metal (Ti, Zr, Hf, Ta, W) and lanthanide complexes. This framework for the preparation of bridging carbenes is also presented. Chapter 1 gives an introduction on ligands found in the literatutre and the importance on amido ligands in catalysis. The second chapter focusses on the use of the disubstituted 1, 8-damiononaphthalene framework in the preparation of bridging carbenes. A dimerization study of a mono carbene is also presented. The third chapter explores the use of the R2DAN ligand to support lanthanide centers. The synthesis of these species and their structural features these complexes are discussed. In the fourth chapter the preparation of group IV complexes bearing R2DAN ligands is presented. A few different approaches to introduce the ligand to a metal centers are outlined and discussed. The influence of the nitrogen substituent on the structure of the complexes is also disscused. Chapter 5 presents the synthesis of tantalum complexes bearing R2DAN ligands along with a structural study of these compounds. A computational study of the structural features of these complexes is presented. The last section of chapter 5 describes the reactivity of the tantalum complexes towards LiNMe2 and MeLi. In Chapter 6 the synthesis of tungsten bis(imido) complexes bearing R2DAN ligands is presented. The fold of the ligands in these complexes is explored using computational chemistry. The reactivity of the tungsten complexes with heterocumelenes and trimethyl aluminum is discussed. The final section of chapter 6 shows the potential of the tungsten complexes as catalysts for cyclotrimerization of isocyanates. Chapter 7 summarizes the work presented in this thesis.