The discussion centers on the possibility of molecules sharing four pairs of bonded electrons, particularly questioning if this can occur with carbon. It is established that carbon cannot form quadruple bonds due to its tetrahedral geometry, which limits orbital hybridization. However, quadruple, quintuple, and even sextuple bonds have been observed in metal-metal complexes, particularly with heavier metals like tungsten and rhenium, where d-orbitals facilitate the formation of delta bonds necessary for such bonding. The conversation also touches on the existence of compounds with double bonds between rhenium and technetium, suggesting that higher-order bonds are feasible in certain contexts. The highest order bond recorded is a sextuple bond, involving the sharing of 12 electrons. Additionally, there is speculation about the physical properties of such compounds, suggesting they may be ultra-hard and ultra-unreactive.
