Geometric isomer

Geometric isomers share connectivity but differ in spatial relationships such as cis/trans or facial/meridional coordination. A reflected chiral facial complex instead gives an enantiomer.

In an octahedral meridional isomer, three selected like donors lie in a plane through the metal and include one trans pair. For three unsymmetrical bidentate ligands, this changes both steric contacts and the identity of opposite donor pairs.

In an octahedral facial isomer, three selected like donors occupy one triangular face and are pairwise cis. Unsymmetrical bidentate ligands can give facial and meridional isomers, each with distinct optical configurations.