Stable four‐membered cyclosilylenes at theoretical levels

Abstract

We aim to develop novel four‐membered cyclosilylenes that contain one (1 and 2), two (3), three (4), and four (5) numbers of Si atoms at the M06/6–311 + G*, B3LYP/aug‐cc‐PVTZ, and MP2/3–21G levels of theory. These structures show high stability and turn out as minima on their energy surfaces for showing no imaginary frequency. Structural and thermodynamic parameters, including bond length, divalent bond angle, singlet‐triplet energy gap (ΔES‐T), highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gap (ΔEH‐L), proton affinity (PA), complexation energy (ΔECom) with CO molecule, nucleophilicity (N), chemical potential (μ), and natural charges, are assessed. The final order of singlet stability appears in the order 1 > 2 > 3 > 4 > 5 at three levels of theory.

Cyclic and linear germylenes as ligands: DFT study

“…[1][2][3][4][5][6][7][8][9][10] These group 14 analogs show the different electronic and structural properties. [11][12][13][14][15][16][17][18] The 2s and 2p orbitals of carbene show a similar spatial extension, whereas the heavier group 14 analogs represent the spatially separated valence ns and np (n > 3) orbitals, due to Pauli repulsion of inner electrons. Therefore, the possibility of hybridization between ns and np orbitals decreases.…”

Activation of dihydrogen by group‐14 substituted germylenes

“…9 The heavier analogs of carbenes, that is, silylenes, germylenes, stannylenes, and plumbylenes, are so-called metallylene 10 that show the different electronic and structural properties. [11][12][13] It is pointed out that such heavier analogs have a lower ability to form hybrid orbital. 14 The 2s and 2p orbitals of carbene show a similar spatial extension, and the heavier group-14 analogs represent the spatially separated valence ns and np (n > 3) orbitals, due to Pauli's repulsion of inner electrons.…”

“…Carbenes have shifted the pattern in our understanding of the effects of ligands in catalysis and have led to seek innovative moves toward utilizing the heavier group‐14 analogs 9 . The heavier analogs of carbenes, that is, silylenes, germylenes, stannylenes, and plumbylenes, are so‐called metallylene 10 that show the different electronic and structural properties 11–13 . It is pointed out that such heavier analogs have a lower ability to form hybrid orbital 14 .…”