Ab Initio Study on the Mechanism of Forming a Germanic Hetero-Polycyclic Compound between Alkylidenegermylene and Ethylene

Abstract

The mechanism of the cycloaddition reaction of forming a germanic hetero-polycyclic compound between singlet alkylidenegermylene and ethylene has been investigated with MP2/6-31G* method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by CCSD(T)//MP2/6-31G* method. From the surface energy profile, it can be predicted that the dominant reaction pathway for this reaction consists of three steps: the two reactants first form a three-membered ring intermediate INT1 through a barrier-free exothermic reaction of 35.4 kJ/mol; this intermediate then isomerizes to an active four-membered ring product P2.1 via a transition-state TS2.1 with a barrier of 57.6 kJ/mol; finally, P2.1 further reacts with ethylene to form the germanic hetero-polycyclic compound P3, for which the barrier is only 0.8 kJ/mol. The rate of this reaction path considerably differs from other competitive reaction paths, indicating that the cycloaddition reaction has an excellent selectivity.

Four‐Membered Heterocycles: Structure and Reactivity

“…The structure of 1,1,3,3-tetramethylgermetane has been studied by gas electron diffraction and ab initio molecular orbital calculations (HF/6-31G Ã and MP2/6-31G Ã ) [431]. An ab initio study has been made on the mechanism of formation of germetane by cycloaddition of alkylidenegermylene and ethylene [432].…”

Theoretical study on the mechanism of cycloaddition reaction between dimethyl germylidene and formaldehyde

“…The mechanism of reaction (4) could be explained with the molecular orbital diagram (Figs. 9 and 10) Compared the cycloaddition reaction between dimethyl germylidene and formaldehyde with the cycloaddition reaction [15] between germylidene and ethylene, we can know that, because of asymmetry of p bond in formaldehyde, the cycloaddition reaction between dimethyl germylidene and formaldehyde is more complex than the cycloaddition reaction between germylidene and ethylene. Only in terms of the dominant reaction channel, the cycloaddition reaction between dimethyl germylidene and formaldehyde has two dominant reaction channels, while the cycloaddition reaction between germylidene and ethylene has only one.…”

“…The barrier to germyne isomerization was predicted to be only 7 kcal/mol and no stable linear germyne structures could be found. With regard to the cycloaddition reaction of the unsaturated germylene, we have done some elementary discussion on the mechanism of the cycloadditional reaction between unsaturated germylenes and symmetric pbonded compounds [15]. In order to further explore the rules of cycloadditional reaction between unsaturated germylenes and asymmetric p-bonded compounds, dimethyl germylidene [(CH 3 ) 2 C@Ge:] and formaldehyde were selected as model molecules, and its mechanism was investigated and analyzed theoretically in terms of the four possible pathways of cycloaddition reaction (considering the hydrogen and methyl transfer simultaneously) as follows: …”

Ab initio Study of Mechanism of Forming a Germanic Hetero‐Polycyclic Compound between Germylidene (H2C=Ge:) and Acetone

“…With regard to the cycloadditon reaction of the unsaturated germylene, we have done some elementary discussion on the mechanism of the cycloadditional reaction between unsaturated germylenes and symmetric π-bonded compounds. 6 In order to further explore the rules of cycloadditional reaction between unsaturated germylenes and asymmetric π-bonded compounds, germylidene and acetone were selected as model molecules, and its mechanism was investigated and analyzed theoretically in terms of the four possible pathways of cycloaddition reaction (considering the hydrogen transfer simultaneously) as follows:…”