A Stable Homoleptic Divinyl Tetrelene Series

Abstract

The synthesis of the new bulky vinyllithium reagent (MeIPr=CH)Li, (MeIPr=[(MeCNDipp)2C]; Dipp=2,6‐iPr2C6H3) is reported. This vinyllithium precursor was found to act as a general source of the anionic 2σ, 2π‐electron donor ligand [MeIPr=CH]−. Furthermore, a high‐yielding route to the degradation‐resistant SiII precursor MeIPr⋅SiBr2 is presented. The efficacy of (MeIPr=CH)Li in synthesis was demonstrated by the generation of a complete inorganic divinyltetrelene series (MeIPrCH)2E: (E=Si to Pb). (MeIPrCH)2Si: represents the first two‐coordinate acyclic silylene not bound by heteroatom donors, with dual electrophilic and nucleophilic character at the SiII center noted. Cyclic voltammetry shows this electron‐rich silylene to be a potent reducing agent, rivalling the reducing power of the 19‐electron complex cobaltocene (Cp2Co).

Zinc-Mediated Transmetalation as a Route to Anionic N-Heterocyclic Olefin Complexes in the p-Block

“…Recently, we reported the preparation of ( Me IPrCH)­Li ( Me IPrCH = [(MeCNDipp) 2 CH] − ; Dipp = 2,6- i Pr 2 C 6 H 3 ), a reagent that can be used to install [ Me IPrCH] − ligands onto inorganic group 14 elements via salt metathesis . A highlight of this work was the isolation of the first two-coordinate acyclic diorganosilylene ( Me IPrCH) 2 Si: ( A in Scheme ).…”

“…A highlight of this work was the isolation of the first two-coordinate acyclic diorganosilylene ( Me IPrCH) 2 Si: ( A in Scheme ). While ( Me IPrCH)Li is a useful reagent, it is unstable in THF and has a limited shelf life, even when kept at −35 °C in the solid state (decomposition becomes noticeable after 1 week). As such, we targeted the preparation of ( Me IPrCH) 2 Zn ( 1 ), hoping that this diorganozinc­(II) reagent could be an easy-to-handle source of the bulky anionic N -heterocyclic olefin (aNHO) ligand [ Me IPrCH] − via transmetalation.…”

“…The formally deprotonated analogues of NHOs, termed here as anionic N -heterocyclic olefins (aNHOs; Scheme ), are highly electron-releasing ligands that can act as 2σ,2π-electron donors. Anionic NHOs have been used in our group to stabilize the acyclic silylene A (Scheme ) , and by Kinjo and co-workers to access a stable cyclophosphenium cation ( B in Scheme ). There are three common routes by which an aNHO ligand can be installed onto a main group center: (1) by in situ deprotonation of an NHO using an exogenous base in the presence of the main group center (e.g., see preparation of B in Scheme ), , (2) reaction of an element halide with a terminally silylated NHO (cf.…”

“…formation of the germyl-complex C in Scheme ), or (3) reaction of a preformed lithiated aNHO complex with element halides (e.g., preparation of silylene A in Scheme ). Routes 1 and 2 occasionally do not work due to a low nucleophility of the NHO source, while route 3 is challenging as the known (isolable) lithiated aNHO (Scheme ) is unstable in THF and decomposes over time in solution and even slowly in the solid state at −35 °C . Herein, we describe the synthesis of a thermally stable Zn­(II) source of anionic N -heterocyclic olefin ( Me IPrCH) 2 Zn ( 1 ) and its use as a transmetalating agent with both halide- and hydride-containing main group substrates (Scheme ).…”

Tetrylenes: Electronic Structure, Stability, Reactivity, and Ligand Properties—A Comparative DFT Study

“…However, we believe that these examples describe the spectrum of approaches for stabilization and, respectively, the spectrum of tetrylenes’ properties. Scheme shows a number of tetrylenes that are not considered in this article, but worth noting: sterically shielded diorgano tetrylenes XI , , XII (Tip = 2,4,6-triisopropylphenyl, Tb = 2,4,6-tris­[bis­(trimethylsilyl)­methyl]­phenyl), , and XIII (Dipp = 2,6-diisopropylphenyl); tetrylenes stabilized by a combination of heteroatom and extensive steric bulk XIV ; Lappert’s diamido compounds XV ; , Veith’s cyclic diamido compounds XVI ; various amidinates XVII ; and diiminates XVIII . Chemistry and various applications of heavier tetrylenes as bond activators, ligands, and building blocks for the construction of new chemical entities was extensively reviewed recently. − …”