Organometallic compounds containing tris(trimethylsilyl)methyl or related ligands

This review is concerned with compounds containing tris(trimethylsilyl)methyl or closely related ligands in which three organosilyl substituents are attached to the central carbon atom. We refer to the prototype ligand derived from (Me3Si)3CH as 'trisyl' (denoted by Tsi) and the broader class as 'trisyl-type'. Such ligands have been attached to elements of all groups of the Periodic Table except 18. Numerous derivatives have been made of the s, p and some f block elements and there are over 300 relevant references in the literature, but few compounds of the transition metals are known as yet. Many organometallic compounds bearing two silicon substituents at the central carbon, i.e. containing ligands such as (Me3Si)2CH or (Me3Si)2C(C5H4N-2), have been described, but their chemistry is often quite different from that of the tris(triorganosilyl)methyl derivatives. The much greater steric protection at an adjacent metal atom when the third organosilyl group is present significantly affects the structures and reactivity of organometallic derivatives. The emphasis is on the 'inorganic' aspects of trisyl chemistry and on the implications of this new work in organometallic chemistry generally. We discuss mainly our own research but give extensive references to chemistry that has been developed by others.