Density Functional Study of Some Germylene Insertion Reactions

Abstract

Complete geometry optimizations were carried out using density functional theory to study potential energy surfaces for the insertion of germylene into C−H bonds of methane. The GeXY + CH4 (GeXY = GeH2, GeCH2, GeH(CH3), Ge(CH3)2, GeHF, GeF2, GeHCl, GeCl2, GeHBr, and GeBr2) systems are the subject of the present study. All the stationary points were determined at the B3LYP/6-311G* level of theory. Our theoretical findings suggest that the computed structures of germylenes are in good agreement with the available experimental results, with the bond lengths and angles in agreement to within 0.04 Å and 1.0°, respectively. A configuration mixing model based on the theory of Pross and Shaik has been used to develop an explanation for the barrier height as well as the reaction enthalpy. Our theoretical findings suggest that the singlet−triplet splitting (ΔE st = E triplet − E singlet) of the GeXY species can be used as a guide to predict its activity for insertion reactions. Thus, the major conclusion that can be drawn from this work is as follows: the more strongly π-accepting, the bulkier, or the more electropositive the substituents, the smaller the ΔE st of GeXY, the lower the activation energy, and the larger the exothermicity for the insertion of GeXY into saturated C−H bonds. In other words, it is the electronic factors, rather than steric factors, that play a decisive role in determining the chemical reactivity of the germylene species.

Theoretical characterization of single-electron iodine-bond weak interactions in CH3…I-Y(Y = BH2, H, CH3, C2H3, C2H, CN, NC) systems

“…The relativistic effective core potential (ECP) basis set of Lanl2dz was used on the iodine atoms, and the 6-311++G(d,p) and aug-cc-pVTZ were used on the other atoms. These methods and basis sets have recently been shown to adequately describe noncovalent interaction systems [13][14][15]. Thus they are reliable for the purpose of our study.…”

“…optimization and transition state calculations [13], and the MP2 method has been used successfully to study weak interactions [15]. The optimized geometric configurations on the potential surfaces of the monomers and CH 3 ···I-Y(Y = BH 2 , H, CH 3 , C 2 H 3 , CCH, CN and NC) complexes are shown in Figure 2, and some important structural parameters obtained at the B3LYP/6-311++G** (in regular type) and MP2/aug-cc-pVTZ (in italics) computational levels are also shown.…”

Theoretical research on the multi-channel reaction mechanism and kinetics of HNCS with OH anions

“…27 The geometries of reactants, intermediates, transition states and products were optimized at the DFT-B3LYP/6-311++G** level. [28][29][30][31] The harmonic vibration frequencies obtained at the corresponding level were used to characterize the stationary points and first-order saddle points. The intrinsic reaction coordinate (IRC) calculation was used to track minimum energy paths from transition structures to stationary points.…”

Theoretical Study of the Reaction Mechanism for SiF2Radical with HNCO

“…32 Geometry optimization at the DFT-B3LYP/6-311++G** level [33][34][35][36] is used to obtain geometries of reactants, intermediates, transition states and products. The harmonic vibration frequencies are also obtained at the corresponding level to characterize the stationary points as local minima or first-order saddle points.…”