3 ISOMERISM IN TRANSITION ELEMENT COMPLEXES

• What type of isomerism can transition element complexes exhibit despite lacking a double bond?

  Geometrical (cis-trans) isomerism
• Which types of complexes exhibit cis-trans isomerism?

  Square planar and octahedral complexes with two pairs of different ligands
• What is an example of a square planar complex that exhibits cis-trans isomerism?

  cis-platin
• How does cis-platin function as an anti-cancer drug?

  It binds to DNA in cancer cells
• Why is trans-platin ineffective in cancer treatment?

  Because it does not bind effectively to DNA
• What condition must a complex ion meet to display geometric isomerism?

  It must have two ligands attached that are different from the rest
• Provide an example of an octahedral complex that exhibits geometric isomerism.

  [Co(NH3)4(H2O)2]2+
• What is the formula for the octahedral complex that can also be written as [Ni(en)2(H2O)2]2+?

  [Ni(H2NCH2CH2NH2)2(H2O)2]2+
• What does the 'cis' isomer indicate in terms of ligand positioning?

  Two 'different' ligands are next to each other
• What does the 'trans' isomer indicate in terms of ligand positioning?

  Two 'different' ligands are opposite each other
• In the complex [Co(NH3)4(H2O)2]2+, if the two H2O ligands are opposite each other, what is the isomer called?

  Trans isomer
• What type of isomerism do octahedral complexes with bidentate ligands exhibit?

  Optical isomerism
• What are the characteristics of optical isomers?

  They have no plane of symmetry and cannot be superimposed on each other
• How do optical isomers differ in their interaction with polarized light?

  They rotate the plane of polarized light in opposite directions
• What is the ligand H2NCH2CH2NH2 commonly referred to as?

  en
• When was cis-platin discovered?

  In the 1960s
• What types of cancer is cis-platin effective in treating?

  Testicular, ovarian, cervical, breast, lung, and brain cancer
• Why do cancer cells respond better to cis-platin than healthy cells?

  Because cancer cells grow and replicate much faster than normal cells
• What is the mechanism by which cis-platin inhibits DNA replication?

  It binds to nitrogen atoms on the bases in DNA and distorts its shape
• What happens to cis-platin after it passes through the cell membrane?

  It undergoes ligand exchange where chlorines are replaced by water molecules
• Why does cis-platin form dative covalent bonds with DNA?

  Because nitrogen is a better ligand than water
• What is one of the adverse effects of cis-platin on healthy cells?

  It causes hair loss due to its effect on rapidly replicating healthy cells
• What is the therapeutic value of cis-platin compared to its side effects?

  Cis-platin is effective in treating cancer, but research aims to target cancer cells more selectively to minimize harm to healthy cells
• What are the key points regarding cis-platin's mechanism of action?

  • Binds to nitrogen atoms on DNA bases
  • Undergoes ligand exchange with water
  • Forms dative covalent bonds
  • Distorts DNA shape, inhibiting replication
• What are the strengths and weaknesses of cis-platin as a cancer treatment?

  Strengths:

  • Effective against various cancers
  • Targets rapidly dividing cells

  
  

  Weaknesses:

  • Affects healthy cells, causing side effects
  • Hair loss due to impact on rapidly replicating healthy cells