Synthesis, reactivity, and catalytic applications of compounds with heavier group 14 elements in usual and low oxidation state

Abstract

Abstract: This thesis provides an overview about the fundamental interest and formidable synthetic challenge regarding the synthesis of compounds with heavier low-valent group 14 elements and covering a brief description of important compounds in this research area is provided. The aim and the results presented in this contribution are outlined. However, thesis consists of 5 chapters of which the introduction (Chapter 1) provides an overview of low-valent chemistry of heavier group 14 compounds and their utility in small molecule activation as well as catalytic application in homogeneous application. Chapter 2 describes the synthesis of Ge(II) dication, [(RNC)4Ge:]2+ [:GeCl3]2- in a single step from the reaction of xylyl isocyanide ligand with GeCl2. The dication species characterized by spectroscopic techniques and additionally the formation of the dication species established by the DFT calculations. Chapter 3 demonstrates the activation of C(sp3)-F and C(sp3)-H bonds of trifluoro acetophenone and acetophenone respectively. Also, the oxidative addition of one of the C-F bonds of hexafluorobenzene as well as octaflurotoluene to a Si(II) center has also been examined. Chapter 4 describes the synthesis and characterization of a neutral penta coordinated Si(IV) compound and its potential use as an efficient catalyst for cyanosilylation of aldehydes under mild reaction conditions. Chapter 5 describes the study of amidinate silylene reaction with pinacolborane and resulted in the cleavage of B-H bond across the Si-C atoms amidinate ligand in a cooperative fashion. Similarly, the reaction of silylene with 4-flurobenzaldehdye that led to the formation of 1,3-dioxaosilalone by carbon–carbon bond formation between two aldehydes. In contrast, benzladehyde resulted in the cleavage of the aldehyde C-H bond and subsequently amidinate ring expansion occurred via insertion of the benzoyl moiety into the C-N bond. The amidinate silylene has also been mediated the catalytic hydroboration and cyanosilylation of carbonyl compounds.