π-Electron systems containing Si=Si double bonds

Abstract

Sterically large substituents can provide kinetic stabilization to various types of low-coordinate compounds. For example, regarding the chemistry of the group 14 elements, since West et al. introduced the concept of kinetic protection of the otherwise highly reactive Si=Si double bond by bulky mesityl (2,4,6-trimethylphenyl) groups in 1981, a number of unsaturated compounds of silicon and its group homologs have been successfully isolated by steric effects using the appropriate large substituents. However, the functions and applications of the Si–Si π-bonds consisting of the 3pπ electrons on the formally sp 2-hybridized silicon atoms have rarely been explored until 10 years ago, when Scheschkewitz and Tamao independently reported the model systems of the oligo(p-phenylenedisilenylene)s (Si–OPVs) in 2007. This review focuses on the recent advances in the chemistry of π-electron systems containing Si=Si double bonds, mainly published in the last decade. The synthesis, characterization, and potential application of a variety of donor-free π-conjugated disilene compounds are described.

The Creation of True Two-Dimensional Silicon Carbide

“…In fact, parameters such as bulkiness of the NMP solvent and i its high surface tension, or hydrogen bonding in IPA and its ability to modify the charge carrier density in materials (via acting as an electron acceptor), could be one of the main driving forces behind the successful isolation of 2D SiC [ 46 , 47 , 48 ]. Earlier studies on silicon/carbon double bonds showed that the sp 3 to sp 2 transitions in Si=C containing materials could be stabilized via mechanisms such as surface depolarization, electronic effects, and steric protection by large substitutes [ 25 , 26 , 49 , 50 , 51 ]. Thus, both NMP and IPA could contribute positively, and even initiate such mechanisms.…”

Two-Dimensional Silicon Carbide: Emerging Direct Band Gap Semiconductor

“…The stability of Si=C bond in such materials is attributed, to a great extent, to the depolarization of the Si=C double bond as a result of the electronic effects of the substituents on the double bond. Such substitutes reduce the natural polarity of the Si=C bond through effects on both the positive charge density at silicon, , and negative charge density, , at carbon [ 21 , 22 ]. In addition to the reduced polarity, steric protection due to bulky substituents, and aromaticity conjugation may also contribute to the stabilization of bonding between Si and C [ 20 , 23 , 24 , 25 , 26 , 27 ].…”

The Different Story of π Bonds

“…At the same time, this allows us to improve our understanding of π-bonding in carbon compounds (by freeing it from misconceptions) and provides new opportunities for applications. Si-Si double bonds, for instance, have been shown to feature rather unique structures [17] (with no analogue in carbon chemistry) that are currently being investigated for integration in carbon π-electronic systems [18]. Si monolayers (a.k.a.…”