Square Planar Complexes (Edexcel International A Level Chemistry)

Revision Note

Sonny

Author

Sonny

Last updated

Square Planar Complexes

  • Sometimes, complexes with four coordinate bonds may adopt a square planar geometry instead of a tetrahedral one
    • Cyanide ions (CN-) are the most common ligands to adopt this geometry
    • An example of a square planar complex is cisplatin
  • The bond angles in a square planar complex are 90o

Chemistry of Transition Elements - Square Planar Complexes, downloadable AS & A Level Chemistry revision notes

Cisplatin is an example of a square planar complex

  • In the 1960s the drug cis-platin was discovered, which has been extremely effective in treating a number of different types cancer such as testicular, ovarian, cervical, breast, lung and brain cancer
  • Cancer cells grow and replicate much faster than normal cells
  • Cis-platin is a square planar molecule that has a geometric isomer with the side groups in different positions
  • Cis-platin has beneficial medical effects by binding to DNA in cancer cells, trans-platin cannot be used in cancer treatment

Chemistry of Transition Elements - Cis-trans in Square Planar, downloadable AS & A Level Chemistry revision notesCis-platin is an example of a square planar transition element complex that exhibits geometrical isomerism

  • The cis-platin works by binding to the nitrogen atoms on the bases in DNA
  • The cis-platin passes through the cell membrane and undergoes ligand exchange where the chlorines are replaced by water molecules
  • The nitrogen is a better ligand than water and forms dative covalent bonds with the cis-platin
  • The cis-platin distorts the shape of the DNA and prevents the DNA from replicating

Chemistry of Transition Elements - Cis-Platin Mode of Action Current SP, downloadable AS & A Level Chemistry revision notes

The process by which cis-platin binds to DNA and prevents replication

Adverse Effects

  • Cis-platin binds to healthy cells as well as cancerous cells, but affects cancer cells more as they are replicating faster
  • Unfortunately, this means that other healthy cells which replicate quickly, such as hair follicles, are also affected by cis-platin
  • This is why hair loss is a side-effect of people undergoing cancer treatment
  • Despite this drawback, cisplatin is a highly effective drug and society needs to find a balance between the adverse effects of drugs and their therapeutic value
  • New therapeutic pathways are constantly under development that aim to deliver drugs that target cancer cells while leaving healthy cells untouched

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Sonny

Author: Sonny

Expertise: Chemistry

Sonny graduated from Imperial College London with a first-class degree in Biomedical Engineering. Turning from engineering to education, he has now been a science tutor working in the UK for several years. Sonny enjoys sharing his passion for science and producing engaging educational materials that help students reach their goals.