Theoretical Study on the Reactivities of Stannylene and Plumbylene and the Origin of their Activation Barriers

Abstract

The potential energy surfaces corresponding to the reactions of heavy carbenes with various molecules were investigated by employing computations at the B3LYP and CCSD(T) levels of theory. To understand the origin of barrier heights and reactivities, the model system (CH3)2X+Y (X=C, Si, Ge, Sn, and Pb; Y=CH4, SiH4, GeH4, CH3OH, C2H6, C2H4, and C2H2) was chosen for the present study. All reactions involve initial formation of a precursor complex, followed by a high-energy transition state, and then a final product. My theoretical investigations suggest that the heavier the X center, the larger the activation barrier, and the less exothermic (or the more endothermic) the chemical reaction. In particular, the computational results show that (CH3)2Sn does not insert readily into C-H, Si-H, C-H, Ge-H, or C-C bonds. It is also unreactive towards C=C bonds, but is reactive towards C identical with C and O-H bonds. My theoretical findings are in good agreement with experimental observations. Furthermore, a configuration mixing model based on the work of Pross and Shaik is used to rationalize the computational results. It is demonstrated that the singlet-triplet splitting of a heavy carbene (CH3)2X plays a decisive role in determining its chemical reactivity. The results obtained allow a number of predictions to be made.

Computational study of 2-vinylsilirane to silacyclopent-3-ene rearrangement

“…Two factors may facilitate synchronous formation of Sn-C bonds. Those are larger atomic radius of Sn atom and weaker interaction of stannylene with double bond due to decrease of affinity to double bonds on going from silylenes to stannylenes [21]. The latter factor suppresses (2 + 1) cycloaddition and promotes (4 + 1) cycloaddition, which is in accord with experimental observations [22] and conclusions from extended Hückel calculations [7].…”

Kinetics and mechanisms of the reactions of transient silylenes with amines

“…The noncatalytic components of the calculated pathways for the reaction of SiMe 2 with MeNH 2 and MeOH are generally analogous to those reported in previous theoretical studies of the reactions of SiH 2 with ammonia, water, and MeOH . This aspect of the results for the SiMe 2 + MeOH system is also in reasonable agreement with those reported by Su from calculations at the CCSD(T)/LANL2DZdp//B3LYP/LANL2DZ level of theory, but the G4 method predicts a greater stabilization of the SiMe 2 –MeOH complex (C O ) and the transition state for unimolecular H‐migration (TS O ) by 2–3 kcal mol –1 , and of the net insertion product by about 6 kcal mol –1 , compared to the earlier calculations. The free energy barrier for unimolecular H‐migration in the SiMe 2 –MeOH complex is predicted to be Δ G ‡ = 15.9 kcal mol –1 at the G4 level of theory, which can be compared to the value of Δ G ‡ = 29.2 kcal mol –1 predicted for the corresponding process in the SiMe 2 –NH 2 Me complex.…”

Application of computational modeling to analyze reactive organotin(IV) species

“…As was noted in the research from Source #1, this reverse trend may be indicative of energy release due to polymerization of these molecules [7,8,29]. The COT that yields the best COMs for larger organotin(IV) molecules may also be the best choice for a smaller organotin(IV) molecule.…”

“…Hence, being able to rely on the generation of a computational optimization modeling (COM) to examine organotin(IV) molecules would facilitate: safer research, the production of new and better applications, a lesser reliance on trial-and-error laboratory experimentation methods, and hastening successful research results [6][7][8].…”

“…Much of this is laboratory research. Yet, there is significant growth in the usage and application of computational modeling research of organotin(IV) molecules [6][7][8]13].…”