Coordination Chemistry: Geometric Isomers

This exercise involves two examples of geometric isomers. The first example is the square planar Pt(NH₃)₂Cl₂ complex. One of the geometric isomers, cisplatin, is used in chemotherapy to treat cancer. The other geometric isomer, transplatin, shows no useful anticancer activity. Carefully examine the structures of the two isomers.

What is the difference between the two geometric isomers?
Formulate a definition for the term "geometric isomers".
The Latin word cis means "next to" and the word trans means "across". Explain how these prefixes are used to identify the geometric isomer.

cis-diamminedichloroplatinum(II) (cisplatin)	trans-diamminedichloroplatinum(II) (transplatin)

A second type of geometric isomerism is illustrated by the octahedral complex Co(NH₃)₃Cl₃. Carefully examine the structures shown below.

What is the difference between the two geometric isomers in this example?
Is the definition of "geometric isomers" you formulated for the case of Pt(NH₃)₂Cl₂ consistent with geometric isomerism in this example?
The terms fac and mer stand for facial and meridional, respectively. Explain how these prefixes are used to identify the geometric isomer.

fac-triamminetrichlorocobalt(III)	mer-triamminetrichlorocobalt(III)

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