ligand substitution Flashcards
what is ligand substitution
when a ligand is replaced by another ligand
why does ligand substitution occur
other ligands form stronger coordination bonds
or there has been a change in equilibrium leads to formation of coordinate bonds
what are h20 ligands usually replaced by
simmilair sized ligands such as cl-
what happens if similar sized ligands are replaced
if neutral then the oxidation number remains the same so does the coordination number
what happens if the ligand is replaced by a larger ligand
if it is negatively charged it will change the coordination number but not the oxidation state
what are the conditions for partial suibstitution
excess dilute reagent
what is removed in partial substitution
square planar ligands is removed
why is nh3 a better ligand than h20
as the lone pair is held less strongly by nitrogen than in oxygen in h20 therefore lone pair is more readily donated
what is the chelate effect
when the substituation of a monodentate with a multidentate which leads to entropy
why does this occur
because it forms a more stable compound
why is the reaction feasible
as the disorder increases so there is positive entropy change
when do we use edta
to rivers to remove heavy metal ions which is poisonous
added to shampoo to remove calcium
used in medicine
why doesn’t ligand substitution occur because of change in enthalpy
metal ions ligand are broken and reformed so stregnths are simiilair and enthalpy change is negligible so reaction doesn’t occur due t enthalpy
what is haemoglobin
a protein found in the blood which help transport oxygen around the body
what does it contain
iron 2+ with an octahedral shape and coordination number of 6 one ligand is a globin group, 4 are haem porphin ring and one is either taken up by h20 or oxygen
