## Chemistry: Molecular Approach (4th Edition)

(a) ${{\left[ Co{{\left( {{H}_{2}}O \right)}_{2}}{{\left( ox \right)}_{2}} \right]}^{-}}$ will exhibit geometrical isomerism. (b) ${{\left[ Cr{{\left( en \right)}_{3}} \right]}^{3+}}$ will exhibit geometrical isomerism. (c) ${{\left[ Co{{\left( {{H}_{2}}O \right)}_{2}}{{\left( N{{H}_{3}} \right)}_{2}}\left( ox \right) \right]}^{+}}$ will exhibit geometrical isomerism. (d) ${{\left[ Ni{{\left( N{{H}_{3}} \right)}_{2}}\left( en \right) \right]}^{2+}}$ will not exhibit geometrical isomerism. (e) $\left[ Ni{{\left( CO \right)}_{2}}C{{l}_{2}} \right]$ will exhibit geometrical isomerism.
Geometrical isomerism is a type of stereoisomerism that results when the ligands bonded to the metal have a different spatial arrangement. Geometrical isomerism (cis–trans isomerism) occurs in the square planar complexes of the type $M{{A}_{2}}{{B}_{2}}$ and octahedral complexes of the $M{{A}_{4}}{{B}_{2}}.$Geometrical isomerism does not occur in tetrahedral complexes because all the bond angles around the central metal are $109.5{}^\circ$ and each comer of a tetrahedron can be considered to be adjacent to all other corners. Similarly, a linear complex cannot exhibit cis–trans isomerism.