Computational and theoretical aspects of structure and bonding in doubly bonded organogermanium compounds

This chapter reviews the theoretical studies of doubly bonded organogermanium compounds. It highlights the insights that these theoretical studies provide on molecular structures, nature of bonding, stability vs. isomeric forms, and the physical properties, of these intriguing compounds. The chapter discusses homonuclear and heteronuclear organogermanium compounds, R₂ Ge=ER₂, E=C, Si, Ge, and extended doubly bonded organogermanium compounds such as germadienes, germaallenes, and germaaromatic derivatives, i.e., germabenezene analogues. It reviews the rapid development of computational packages for electronic structure calculations in the last three decades. Currently, these software packages apply mainly two theoretical approaches, ab initio wave-function based molecular orbital methods, and electron density based density functional theory methods. The main computational criteria for predicting the degree of aromaticity are: the geometric criterion, the energetic criterion, and the magnetic criterion.