Expanding the applicability of electrostatic potentials to the realm of transition states

Theoretical study of a derivative of chlorophosphine with aliphatic and aromatic Grignard reagents: SN2@P or the novel SN2@Cl followed by SN2@C?

The proposed SN2 reactions of a hindered organophosphorus reactant with aliphatic and aromatic nucleophiles [Ye et al., Org. Lett., 2017, 19, 5384–5387] were studied theoretically in order to explain the observed stereochemistry of the products.

An electrolyte- and catalyst-free electrooxidative sulfonylation of imidazo[1,2-a]pyridines

An electrolyte- and catalyst-free electrooxidative C–H activation reaction is developed to afford 3-sulfonylated imidazo[1,2-a]pyridines in good to excellent yields.

Hemiaminal route for the formation of interstellar glycine: a computational study

Calculations related to two simple two-step paths (path-I: [Formula: see text] path-II: [Formula: see text]) for the formation of glycine have been discussed. Calculations show that at interstellar conditions these two paths are feasible only in hot cores, not in the cold interstellar clouds (cold core formation is possible only if CH₂ = NH, H₂O (excess) and CO of path-II, react in a concerted manner). For the laboratory synthesis of glycine, the possibility suggested is via path-I and the reaction being carried out as controlled temperature one-pot synthesis. This study can also be extended to other α-amino acids and possibly enantiomeric excess can be expected. We think this work will not only be able to enrich our future understanding about the formation of amino acids in interstellar medium but also be able to suggest alternative paths for laboratory synthesis of amino acids using either Strecker's or Miller's ingredients. Graphical abstract Using computational calculations, two different reaction paths which go through a hemiaminal (α-hydroxyamine) intermediate have been proposed. It has been proposed that the reaction [Formula: see text] is a thermodynamically favorable reaction path in the laboratory conditions, if carried out as a controlled temperature one-pot synthesis. On the hand, it has been argued that the reaction[Formula: see text] is a feasible reaction path in the interstellar conditions, if it proceeds not via the hemiaminal route, rather in a concerted reaction path.

Insight into the Effects of Electrostatic Potentials on the Conversion Mechanism of the Hydrogen-Bonded Complexes and Carbon-Bonded Complexes: An Ab Initio and Quantum Theory of "Atoms in Molecules" Investigation

Carbon bond and hydrogen bond are common noncovalent interactions; although recent advances on these interactions have been achieved in both the experimental and computational aspects, little is known about the conversion mechanism between them. Here, MP2 calculations with aug-cc-pVDZ basis set (aug-cc-pVDZ-pp for element Sn) were used to optimize the geometric configurations of the hydrogen-bonded complexes MH₃F···HCN (M = C, Si, Ge, and Sn), carbon-bonded complexes HCN···MH₃F (M = C, Si, Ge, and Sn), and transition states; the conversion mechanism between these two types of interactions has been carried out. The molecular electrostatic potential, especially the σ-hole, is directly related to the flatten degree of intrinsic reaction coordinate (IRC) curve. The energy barriers from the hydrogen-bonded complexes to the carbon-bonded complexes are 6.99, 7.73, 10.56, and 13.59 kJ·mol^-1. The energy barriers from the carbon-bonded complexes to the hydrogen-bonded complexes are 4.65, 7.81, 9.10, and 13.04 kJ·mol^-1. The breakage and formation of the bonds along the reaction paths have been discussed by the topological analysis of electronic density. The energy barriers are obviously related to the width of the structure transition region (STR). For the first derivative curve of IRC energy surface versus reaction coordinate, there is a maximum peak and a minimum peak, reflecting the structural transition states in the ring STRs.

Reactivity of phosphorus mononitride and interstellar formation of molecules containing phospazo linkage: A computational study on the reaction between HSi (X2Π) and PN (X1Σ+)

Phosphorus mononitride (PN) shows some interesting chemistry due to its low dissociation energy (compared to N2) and small dipole moment (zero dipole moment for N2). In this work, a reaction between HSi ([Formula: see text]) and PN ([Formula: see text]) has been studied using various computational methods. Analysis of the doublet surface of the [Formula: see text] reaction indicates that the reaction is exothermic in nature leading to the formation of various products. In view of the barrierless association of the reactants and exothermic nature for the product formation, it is suggested that species like HPNSi, cyclic-SiN(H)P (these two most stable isomers have phosphazo linkage) and HSiNP (third most stable isomer has phosphdiazo linkage) can possibly be detected in the interstellar medium. In view of the potential applications of phosphazo compounds in amide synthesis and pervasive nature of amide linkages in the nature, possible interstellar prebiotic applications can be advocated for these compounds.

Formation of a pre-reaction hydrogen-bonded complex and its significance in the potential energy surface of the OH + SO2→ HOSO2 reaction: A computational study

Using computational calculations, we have revisited the potential energy surface (PES) of the reaction between OH and SO2, which is believed as the rate-limiting step in the atmospheric formation of H2SO4. In this work, we report for the first time the presence of a pre-reaction hydrogen-bonded complex between OH and SO2 in the reaction PES. Based on this finding, it has been shown that the reaction can be considered as a two-step process in which the first step is the formation of the pre-reaction complex and the second step is the transformation of this complex to the product. It was observed that due to the presence of this pre-reaction complex as a potential well in the reaction PES, the barrier height got increased by around two-fold for the second step. Based on this observation, it has been proposed that the kinetics of the reaction is going to be affected. Also based on the analysis of the geometries of this pre-reaction complex and the transition state, it has been argued that the step involving the transformation of this pre-reaction complex to the product via the transition state is going to be the slowest step as this transformation involves large structural changes of the stationary points involved.