Studies of low oxidation state group 13 and 14 metallacycles

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.

本论文主要围绕一价镓的氮杂环卡宾（N-heterocyclic carbene, NHC）类似物[K(四甲基乙二胺, tetramethylethylenediamine, tmeda)][:Ga{[N(Dip)C(H)]₂}]的反应性展开研究，其中Dip代表2,6-二异丙基苯基（2,6-diisopropylphenyl, C₆H₃Pri₂-2,6）。本研究同时探索了首例单核一价锗自由基（Ge(I) radical）的合成路径。全文研究内容共分为五章：

第一章为低价第13族与第14族元素化学的综述性介绍，重点阐述第13族一价金属与第14族二价金属的氮杂环卡宾类似物的合成方法。

第二章综述了[K(tmeda)][:Ga{[N(Dip)C(H)]₂}]与第2族及第12族金属前驱体的反应性研究。本章讨论了镁、钙、锶、钡、锌及镉的卤化物与[K(tmeda)][:Ga{[N(Dip)C(H)]₂}]的反应，并首次报道了经晶体结构表征的镉-镓键合分子配合物。

第三章综述了[K(tmeda)][:Ga{[N(Dip)C(H)]₂}]与选定镧系金属前驱体的反应性研究。二碘化钐、二碘化铕、二碘化镱、二碘化铥及三碘化铈与[K(tmeda)][:Ga{[N(Dip)C(H)]₂}]的反应，得到了一系列新型镧系-镓基物种，其中包含首例经晶体结构表征的Ga-Tm或Ga-Sm键合配合物。

第四章详细阐述了通过还原位阻较大的β-二亚胺合二价锗前驱体，首次合成单核一价锗自由基的过程。本研究通过晶体衍射、电子顺磁共振（Electron Paramagnetic Resonance, EPR）、电子核双共振（Electron Nuclear Double Resonance, ENDOR）光谱及理论分析相结合的手段，验证了该物种中锗的+1氧化态。

第五章介绍了多项零散研究结果，主要来源于尝试合成低氧化态p区元素的位阻型胍基配合物的相关工作。