Examination of ligand effects on the reactivity and reduction chemistry of trivalent lanthanide metallocene complexes

This dissertation focuses on methods of expanding lanthanide-based reduction beyond those of traditional divalent organometallic complexes. Specifically, the effect ligands have in modifying the reduction chemistry of the lanthanides was probed. Comparisons of ligand-based reactivity in trivalent lanthanide complexes where the metal does not formally participate in the redox process have led to unique modes of reactivity, and as a result, new trivalent lanthanide reduction systems have been identified. This reactivity can be distinct from previously identified lanthanide reduction systems and demonstrates how metal size can lead to variations in the reduction chemistry.;Chapter 1 describes the unusual ligand based reactivity of the allyl complex, (C5Me5)2Y(eta3-C 3H5). The yttrium allyl complex reacts with 9-borabicyclo[3.3.1]nonane (9-BBN) to form two products which were isolated in the same single crystal: one resulted from the addition of 9-BBN to the olefinic portion of the allyl, {(C5Me5)2Y[eta3-C3 H4(BC8H14)]} and the other was an adduct between [(C5Me5)2YH]x, generated in situ, and 9-BBN to give {(C5Me 5)2Y(mu-H)2BC8H14}.;Chapter 2 describes a different aspect of lanthanide hydride chemistry involving the expansion of divalent reductive reactivity to trivalent systems. In this Chapter the capacity of lanthanide hydrides to serve as reductants, providing one electron per equivalent of (H)1- ligand, was identified. These studies demonstrated a new mode of reactivity for the lanthanide hydrides and provide a new system for investigating divalent-like reduction using trivalent metals.;In Chapter 3, the reduction chemistry of [(C5Me4H) 2Ln(THF)]2(mu-eta2:eta2-N 2) with the largest and the smallest lanthanides, La and Lu, was explored in order to investigate the relationship between metal size and reactivity. This system demonstrated that metal size is an important factor in determining the reductive reactivity of lanthanide complexes and resulted in the isolation of an oxalate complex, [(C5Me4H)2Lu] 2(mu-eta2:eta2-C2O 4), formed from the reductive coupling of CO2.;Chapter 4 extends the Ln2(mu-eta2:eta 2-N2) reduction system to the previously uncharacterized [(C5Me4H)2Y(THF)]2(mu-eta 2:eta2-N2) complex. The reactivity of this complex was examined and it was shown to effect an unusual reduction of an azide, Me3SiN3, to form an amide [N(SiMe 3)2]1- ligand, which was then isolated as (C5Me4H)2Y[N(SiMe3)2].