Studies of low oxidation state group 13 and 14 metallacycles

Abstract

This thesis is mainly concerned with investigations into the reactivity of the gallium(I) N-heterocyclic carbene (NHC) analogue, [K(tmeda)][:Ga{[N(Dip)C(H)]2}] (Dip = C6H3Pri2-2,6). The preparation of the first monomeric Ge(I) radical was also investigated. Work carried out in these areas is divided into five chapters. Chapter 1 provides a general introduction to sub-valent group 13 and 14 chemistry, with an emphasis on the preparation of group 13 metal(I) and group 14 metal(II) N-heterocyclic carbene analogues. Chapter 2 summarizes investigations into the reactivity of [K(tmeda)] [:Ga{[N(Dip)C(H)]2}] towards groups 2 and 12 metal precursors. Reactions of magnesium, calcium, strontium, barium, zinc, and cadmium halides with [K(tmeda)][:Ga{[N(Dip)C(H)]2}] are discussed, and the first structurally characterized cadmium-gallium bonded molecular complex is reported. Chapter 3 summarizes investigations into the reactivity of [K(tmeda)] [:Ga{[N(Dip)C(H)]2}] towards selected lanthanide metal precursors. Reactions of samarium(II), europium(II), ytterbium(II), thulium(II), and cerium(III) iodides with [K(tmeda)][:Ga{[N(Dip)C(H)]2}] have given rise to a number of novel lanthanide-gallyl species, including the first structurally characterized GaTm or GaSm bonded complexes. Chapter 4 details the preparation of the first monomeric Ge(I) radical via the reduction of a bulky β-diketiminato germanium(II) precursor. The verification of the +1 oxidation state in this species was achieved using a combination of crystallographic, EPR and ENDOR spectroscopic, and theoretical analyses. Chapter 5 describes several miscellaneous results, largely derived from attempts to prepare bulky guanidinato complexes of p-block elements in low oxidation states.