DMAP-stabilized bis(silyl)silylenes as versatile synthons for organosilicon compounds

Abstract

DMAP-stabilized silylenes 1a–c, which are convenient, room temperature stable synthetic equivalents for the corresponding highly reactive free bis(silyl)silylenes are reported.

Molecular Main Group Metal Hydrides

“…From the resulting monomeric silylene complexes, Si­(IV) hydrides can be obtained by the direct oxidative addition of H 2 , as outlined in Scheme , ,,, or via NH 3 activation . The donor-stabilized bis­(silyl)­silylenes R 3 Si­(R′ 3 Si)­Si·DMAP (R = t Bu, R′ = Me; 833 ; R = R′ = Si t Bu 2 Me; 834 ; R = R′ = Me; 835 ), react with 1 atm of H 2 at 65 °C to produce the corresponding dihydrosilanes 836 − 838 in quantitative yields, with loss of DMAP in each case . In a similar fashion, the amido­(silyl)­silylene {Me 3 Si­(Dipp)­N}­{(Me 3 Si) 3 Si}­Si: ( 839 ) and in situ generated (IPr=N)­{(Me 3 Si) 3 Si}­Si: ( 841 ) react with H 2 to give the silicon­(IV) dihydrides 840 and 842 (Scheme ).…”

“…), acyclic silylenes with ligands based on the electropositive donor elements B or Si (i.e., boryl, -BR 2 , or silyl -SiR 3 groups) in conjunction with nitrogen-based ligands are often employed; such ligand combinations result in the small HOMO-LUMO energy gaps needed for small molecule activation. 975 From the resulting monomeric silylene complexes, Si(IV) hydrides can be obtained by the direct oxidative addition of H 2 , as outlined in Scheme 133, 67,69,1086,1087 or via NH 3 activation. 1088 The donor-stabilized bis(silyl)silylenes R 3 Si(R′ 3 Si)Si•DMAP (R = t Bu, R′ = Me; 833; R = R′ = Si t Bu 2 Me; 834; R = R′ = Me; 835), react with 1 atm of H 2 at 65 °C to produce the corresponding dihydrosilanes 836−838 in quantitative yields, with loss of DMAP in each case.…”

Acetylene and Ethylene: Universal C2 Molecular Units in Cycloaddition Reactions

“…In 2020, it was reported that silylenes (R 2 Si:), the heavier congeners of carbenes, can also be used in cycloaddition reactions with ethylene. 45 The active species were stabilized with 4-(dimethylamino)pyridine (DMAP), and after the reaction, DMAP was easily isolated through precipitation. As a result, a series of siliranes was obtained (Scheme 12 ).…”

Rapid and Mild Synthesis of an NHC-Coordinated Bis(trimethylsilyl)silylene via Elimination of Halotrimethylsilane

“…40,41 The reaction of 2 with 2,3-dimethylbutadiene at 60 °C provided (1 + 4) cycloadduct 5 (69% yield) and free IMe 4 , while this reaction did not proceed at room temperature. This result indicates that 2 serves as a surrogate of bis(trimethylsilyl)silylene, 42,43 although it is unclear whether 2 dissociates into bis(trimethylsilyl)silylene and IMe 4 in solution at 60 °C. In addition, 2 reacted with Me 3 SiI to provide silylimidazolium 3 (83% yield).…”

“…The molecular structure of 4 obtained by single-crystal XRD analysis (Figure b) indicated that the Si1–C1 distance in 4 [1.9466(13) Å] is close to that in 2 [1.9354(11) Å] and Si1–B distance in 4 [2.1504(14) Å] is slightly longer than those of reported NHC-coordinated silylene-borane complexes [1.999–2.074 Å]. , The reaction of 2 with 2,3-dimethylbutadiene at 60 °C provided (1 + 4) cycloadduct 5 (69% yield) and free IMe 4 , while this reaction did not proceed at room temperature. This result indicates that 2 serves as a surrogate of bis­(trimethylsilyl)­silylene, , although it is unclear whether 2 dissociates into bis­(trimethylsilyl)­silylene and IMe 4 in solution at 60 °C. In addition, 2 reacted with Me 3 SiI to provide silylimidazolium 3 (83% yield).…”