Trans Effect and Cisplatin Exercises

These questions deal in part with concepts presented in the paper by Alderden et al., so please make sure you have read this paper before working out your answers.

1. What is the electronic structure attribute that makes CO and C₂H₄ such strong trans effect ligands?
2. What is a distinguishing feature of the reaction coordinate for ligand substitution at square planar platinum in the case of ethylene as the ligand that is trans to the leaving group?
3. What is the distinguishing feature of the reaction coordinate for ligand substitution at square planar platinum in the case of hydride as the ligand that is trans to the leaving group?
4. What is the product of reaction of K₂[PtCl₄] with excess KI?
5. What is the product of reaction of [Pt(NH₃)₄]Cl₂ with 2 equiv HCl?
6. The discovery of cisplatin as an antitumor agent grew out of what initial scientific inquiry?
7. In what year was cisplatin first synthesized, and who was the first to correctly propose its square planar configuration?
8. Explain why it is that transplatin lacks anticancer activity, in contrast with cisplatin.
9. What is the name given to the Pt-OH₂ bond lengthening when it is trans to a hydride (H^-) compared to another H₂O?
10. To which residues of DNA does platinum bind in the most important adduct of platinated DNA? Explore the structure using the Jmol applet.
11. In the most important adduct of platinated DNA, is platinum serving to produce an inter- or an intra-strand DNA crosslink?
12. For octahedral metal complexes [Fe(CN)₆]^4- and Mo(CO)₃(MeCN)₃, what is the most likely substitution mechanism?  Why?
13. Order the rates of substitution for the following complexes: Cr(NH₃)₆³⁺, Co(NH₃)₆³⁺, Rh(NH₃)₆³⁺, Ir(NH₃)₆³⁺, Mn(H₂O)₆²⁺, Ni(H₂O)₆²⁺, Cu(H₂O)₆²⁺, Cr(H₂O)₆³⁺.