Taming Silicon Congeners of CO and CO₂: Synthesis of Monomeric Si^II and Si^IV Chalcogenide Complexes

Abstract

The synthesis of the unprecedented monomeric Si selenide complex (bis-NHC)Si=Se→GaCl 2 (bis-NHC=bis-N heterocyclic carbene, H C[{NC(H)=C(H)N(Dipp)}C:] , Dipp=2,6-iPr C H ), bearing the elusive SiSe ligand as a heavy CO homologue by the reaction of the silylone-GaCl adduct (bis-NHC)Si→GaCl 1 with elemental selenium in acetonitrile, is reported. The similar conversion of 1 with excess selenium conducted in THF afforded the SiSe complex (bis-NHC)Si(=Se)Se→GaCl 3. Remarkably, the reaction of 1 with Te=P(nBu) as a gentle Te transfer reagent led to the isolation of the monomeric SiTe complex (bis-NHC)SiTe 4, the first structurally characterized Lewis acid free heavy CO homologue complex. The isolated compounds 2, 3, and 4 have been fully characterized, including single-crystal X-ray diffraction analyses. Their electronic structures and spectroscopic data have also been studied by quantum-chemical calculations.

Tetrylones: An Intriguing Class of Monoatomic Zero‐valent Group 14 Compounds

“…The synthesis of the unprecedented momomeric bis(NHC)Si(Se)Se→GaCl 3 complex 35 was accomplished by the reaction of silylone→GaCl 3 adduct 31 with elemental selenium in THF (Scheme ) . The 29 Si{ 1 H} NMR spectrum of 35 displays a signal δ =−69.9 ppm, which is upfield shifted compared to the solid state CP/MAS 29 Si{ 1 H} NMR chemical shift of bis(NHC)Si(S)S→GaCl 3 complex 34 ( δ =−40.0 ppm) .…”

“…To synthesize the heavier chalcogenide complexes of tetrylone, the reaction of silylone→GaCl 3 adduct 31 with elemental tellurium has been attempted . However, elemental tellurium does not react with 31 in acetonitrile and the proceeds very slowly in THF.…”

“… NRT analyses of 35 and 36 , which identified 35A–C and 36A–C as the predominant resonance structures …”

Taming Silicon Congeners of CO and CO2: Synthesis of Monomeric SiII and SiIV Chalcogenide Complexes

“…Right:M olecular structure of 4. [14] Ellipsoids are set at 50 %probability;Hatoms are omitted for clarity.S elected interatomic distances []and angles [8 8]: Si1-Te1 2.389(4), Si1-Te2 2.436(2), Si1-C1 1.926(4), Si1-C2 1.944(3);C 2-Si1-C1 90.4(1), Te1-Si-Te2 128.42-(3). [a] NPA charges (q), [b] and Wiberg bond indices (WBI) [b] for compounds 2' ', 3' ' (E = Se), and 4' ' (E = Te).…”

S–H Bond Activation in Hydrogen Sulfide by NHC-Stabilized Silyliumylidene Ions

“…Key to these developments have been the usage of suitable synthetic methodologies in combination with thermodynamic and kinetic stabilization by appropriately chosen ligands. In particular, for the heavier carbon analogue silicon, a plethora of studies reported new low-valent compounds in recent years [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and the chemistry of silylene base adducts has already been carefully developed [14,[26][27][28][29][30][31][32][33][34][35][36]. Before these findings, silyliumylidene ions, cationic Si(II) species were found to be promising as similar versatile Lewis amphiphiles [37,38].…”