Approaching through the chronicles of species with low-valent silicon and their transition metal complexes: Structure, bonding and potential catalytic applications

Abstract

Compounds with low-valent silicon characterized by an oxidation state lower than +IV (the most stable oxidation state for silicon) represent one of the fascinating and rapidly emerging fields of research in main-group chemistry. The primary challenge associated with the research involving compounds with low-valent silicon is their synthesis and isolation due to their high reactivity and tendency to attain the most stable oxidation state. Despite the challenges associated with compounds of low-valent silicon, their study is crucial as their unique reactivity can be explored for various catalytic transformations. In addition, compounds of low-valent silicon can serve as ligands to transition metals, which can lead to the formation of metal complexes that may have potential for catalytic applications. The review commences with the highlights of the milestone discoveries in the field of compounds with low-valent silicon. The next section of the review discusses the structure and bonding properties of different classes of compounds with low-valent silicon according to their oxidation state [+II (silylene, disilene, disilyne and silyliumylidene ion) and 0 (silylone)]. The subsequent section provides insights into different binding modes of compounds with low-valent silicon to transition metals. A detailed emphasis is given on some notable examples of transition metal complexes supported compounds with low-valent silicon as ligands, focusing on their synthesis, characterization, and potential catalytic applications.