Planar hexacoordinate carbon
# Planar hexacoordinate carbon

Planar hexacoordinate carbon in chemistry describes a molecular geometry featuring a planar arrangement of carbon with six surrounding atoms. No actual chemical compounds having this particular hexacoordinate configuration have been reported but quantum mechanical methods have demonstrated that these molecules are a possibility. Examples of molecules investigated with computational methods are the $B_6C$ dianion, the $CN_3Be_3^+$ ion, the $CO_3Li_3^+$ ion and the $CN_3Mg_3^+$ ion. A simulated $Be_2C$ monolayer is reported to consist of quasi-planar hexacoordinate carbon atoms.

On the other hand, experimental research has confirmed that the pentagonal-pyramidal hexamethylbenzene ion, $C_6(CH_3)_6^{2+},$ contains a hexacoordinate carbon atom. Furthermore, a heptacoordinate carbon atom has been predicted to be involved in a stable hexagonal-pyramidal configuration of tropylium trication, $(C_7H_7)^{3+}.$

