GeCl2 cycloaddition reactions to unsaturated organic compounds taking ethylene, buta-1,3-diene, and hexa-1,3,5-triene as examples: a quantum chemical study

Abstract

The cycloaddition reactions of dichlorogermylene GeCl 2 to ethylene, buta 1,3 diene, and hexa 1,3,5 triene were studied within the framework of the density functional theory (PBE and B3LYP density functionals) and by the ab initio CBS QB3 method. The energy characteristics of the reaction of GeCl 2 with ethylene were refined and non empirical quantum chemical calculations of reaction pathways in the GeCl 2 + buta 1,3 diene and GeCl 2 + hexa 1,3,5 triene systems were carried out for the first time. It was shown that the [2+1] cycloaddition reactions are kinetically hindered and thermodynamically unfavorable, while the [4+1] and [6+1] cyclo addition reactions are characterized by low barriers and result in thermodynamically favorable products. For the [4+1] cycloaddition to buta 1,3 diene and [6+1] cycloaddition to hexa 1,3,5 triene, the most energetically favorable reaction pathways involve a suprafacial and an tarafacial approach of reactants, respectively.