File:Chapter 23 - Coordination Chemistry (Geometrical Isomerism) pp 188-196.pdf

Two or more compounds having same molecular formula (same molecular weight) but different structural formula and property are known as isomers and the phenomenon is called isomerism. In metal complex the ligand may occupy different types of positions around the central metal atom which are either adjacent to each other (cis isomer) or opposite to one another (trans isomer). So geometrical isomerism is also known as ‘cis-trans’ isomerism. Geometrical isomerism is very much common in coordination compounds for coordination number 4 and 6.Tetrahedral complexes do not show geometrical isomerism due to all four ligands are equidistant to one another. Square planar complexes with general formula Ma4, Ma3b, Mba3 do not show cis-trans isomerism due to equivalent spatial arrangement. Octahedral complexes with general formula Ma6, Ma5b, Mba5 do not show cis-trans isomerism.