isomerism in coordination complexes

Is there any difference between geometrical and cis-trans isomerism in coordination complexes, because in my book it is given that complexes of the form [Ma4bc] does not show cis-trans isomerism but shows geometrical isomerism




Geometrical isomers are compounds where all atoms are connected to the same atoms but their arrangement in space differs. This does include *cis-trans* isomers but in the context of coordination compounds also *fac-mer* isomers ($\ce{[MA3B3]}$ cases).


The case of $\ce{[MA4BC]}$ is tricky. In principle, they show the same two possible arrangements that, if $\ce{B}=\ce{C}$ would be termed *cis* and *trans*. In lab practice, most chemists would use *cis* and *trans* to describe them. In IUPAC theory, that response and terminology may or may not be valid.


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