A mechanistic investigation on the formation and rearrangement of silaspiropentane: A theoretical study

Abstract

The formation of silaspiropentane from addition of singlet silacyclopropylidene 1 and silacyclopropylidenoid 8 to ethylene has been investigated separately at the B3LYP, X3LYP, WB97XD, and M05-2X theories using the 6-31+G(d,p) basis set. The silacycloproylidenoid addition follows a stepwise route. In contrast, a concerted mechanism occurs for silacyclopropylidene addition. Moreover, the intramolecular rearrangements of silaspiropentane 9 to methylenesilacyclobutane 11 and 2-silaallene + ethylene 12 have been studied extensively. The required energy barrier for the isomerization of 9 to 10 was determined to be 44.0 kcal mol(-1) at the B3LYP/6-31+G(d,p) level. After formation of 10, the rearrangement to methylenesilacyclobutane 12 is highly exergonic by -15.9 kcal mol(-1), which makes this reaction promising. However, the conversion of 9 to 11 is calculated to be quite endergonic, by 26.5 kcal mol(-1).

Cycloaddition reactions of silacyclopropylidenoids to ethylene

“…Collectively, the mechanistic pathway of 1F is appeared to bear a reasonable resemblance to our previous report on 1Br reaction. 18 Figure 1. The proposed addition reaction mechanism of 1F to ethylene.…”

“…12 Despite considerable potential in this regard, 9,14,15 reports on those of cyclic analogues (C 2 H 4 SiLiX, X = F, Cl, or Br) are still rare. [16][17][18] Very recently, we have performed a series of theoretical calculations on the formation and rearrangement of silaspiropentane 2 from addition of lithium-bromosilacyclopropylidenoid 1Br to ethylene (Scheme 1). 18 The nature of the addition reaction of 1 to ethylene is found to be endergonic by ΔG = 33.9 kJ/mol, whereas the formation process of 4 is exergonic by ΔG = -60.6 kJ/mol at the B3LYP/6-31+G(d,p) level of theory.…”

“…[16][17][18] Very recently, we have performed a series of theoretical calculations on the formation and rearrangement of silaspiropentane 2 from addition of lithium-bromosilacyclopropylidenoid 1Br to ethylene (Scheme 1). 18 The nature of the addition reaction of 1 to ethylene is found to be endergonic by ΔG = 33.9 kJ/mol, whereas the formation process of 4 is exergonic by ΔG = -60.6 kJ/mol at the B3LYP/6-31+G(d,p) level of theory. In the present computational study, we would like to distil a general message for the effects of halogen and solvent (Tetrahydrofuran, THF) on the possible cycloaddition reactions of silacyclopropoylidenoids (C 2 H 4 SiLiX, denoted as 1X with X = C, Si, or Ge) to C=C double bond of ethylene.…”

Experimental study on the influence of pore structure on spontaneous imbibition in marine black shale

“…Spontaneous imbibition, also known as capillary filling, occurs naturally without external pressure differences (Cai et al, 2014;Dou et al, 2021). The characteristics of shale play a significant role in influencing this process (Yildiz and Akin, 2016;Shen et al, 2017;Cai et al, 2020). Various techniques are available for studying spontaneous imbibition processes, including X-ray scanning, computed tomography, neutron imaging, low field nuclear magnetic resonance (NMR), and numerical simulations (Yue et al, 2019;Lu et al, 2022).…”

New monodentate and bidentate silylene ligands byDFT

“…[20] Monodentate silylenes [21] are the simplest silylene ligands, which as catalysts show excellent chemo-, regio-, and stereoselective activities. [22][23][24][25] The first example of silylene applied in catalysis was a NHSi, bearing a two-coordinate Si center. [26] Bidentate silylenes constitute another important type of ligands.…”