Question

Draw the structures of the following:
(a) $cis$ - dichloro tetracyanochromate (III) ion
(b) $mer$ - triammine trichlorocobalt (III)
(c) $fac$ - triaquatrinitro - $N$ - cobalt (III)

Answer 1

The structures of the given complexes are shown:

a) cis-dichlorotetracyano-chromate (III) : the suffix $ate$ shows its an anionic ligand complex. cis- represents that the same ligands are "next to each other" i.e. at 90 degrees in relation to the central metal ion, whereas in the trans- isomer they are "opposite each other", i.e. at 180 degrees relative to the central metal ion.

(b) mer-triamminetrichlorocobalt(III) : placing the 3 same groups around the centre gives rise to the meridional isomer.

(c) fac-triaquatrinitro-N-cobalt(III) : placing the 3 same groups on one face of the octahedral gives rise to the facial isomer.