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Reactivity of the Bicyclic Amido‐Substituted Silicon(I) Ring Compound Si 4 {N(SiMe 3 )Mes} 4 with FLP‐Type Character
Author(s) -
Schwedtmann Kevin,
Quest Michael,
Guddorf Benedikt J.,
Keuter Jan,
Hepp Alexander,
Feldt Milica,
Droste Jörn,
Hansen Michael Ryan,
Lips Felicitas
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202103101
Subject(s) - lewis acids and bases , chemistry , adduct , protonation , reactivity (psychology) , carbene , bicyclic molecule , medicinal chemistry , ring (chemistry) , stereochemistry , diphenylacetylene , ion , organic chemistry , catalysis , medicine , alternative medicine , pathology
The bicyclic amido‐substituted silicon(I) ring compound Si 4 {N(SiMe 3 )Mes} 4 2 (Mes=Mesityl=2,4,6‐Me 3 C 6 H 2 ) features enhanced zwitterionic character and different reactivity from the analogous compound Si 4 {N(SiMe 3 )Dipp} 4 1 (Dipp=2,6‐ i Pr 2 C 6 H 3 ) due to the smaller mesityl substituents. In a reaction with the N‐heterocyclic carbene NHCMe4(1,3,4,5‐tetramethyl‐imidazol‐2‐ylidene), we observe adduct formation to give Si 4 {N(SiMe 3 )Mes} 4 ⋅ NHCMe4( 3 ). This adduct reacts further with the Lewis acid BH 3 to yield the Lewis acid–base complex Si 4 {N(SiMe 3 )Mes} 4 ⋅ NHCMe4 ⋅ BH 3 ( 4 ). Coordination of AlBr 3 to 2 leads to the adduct 5 . Calculated proton affinities and fluoride ion affinities reveal highly Lewis basic and very weak Lewis acidic character of the low‐valent silicon atoms in 1 and 2 . This is confirmed by protonation of 1 and 2 with Brookharts acid yielding 6 and 7 . Reaction with diphenylacetylene only occurs at 111 °C with 2 in toluene and is accompanied by fragmentation of 2 to afford the silacyclopropene 8 and the trisilanorbornadiene species 9 .