Mikeh Flashcards
What happens to electrons placed in the dxy,dxz, dyz orbitals
These ligands point to the spaces between ligands so electrons experience less repulsion and are therefore stabilised while the others are destablilised. This is for octahedral complexes
In tetrahedral complexes which orbitals are stabilised
The two which lie along the axis are stablilsed and the ones pointing towards ligands are destablised.
In square planar complexes which orbitals are stabilised
The ones with Z components
What three things effect delta Oct
oxidation - higher oxidation higher the value
Row of metal - Down a row delta oct increases
The type of ligand - weak field give rise to small values and strong field gives rise to large values.
How do you find the energy of a peak
E = hc
h is planks and c = speed of light/ wavelength in m
multiply that by avagadros and divide by 1000
Why is the peak so large on aabsorption graph
molecules are vibrating, Different lenght of M - L cause different values in delta Oct. If its a long bond then there is less repulsion felt between ligands and electrons so delta oct is less and absorption will move to lower energy (longer wavelenght)
and vice versa
Why is there a peak going up at the beginning of the spectra
Charge transfer absorption
why is there a shoulder
2 possible transitions from dxy to either dx2-dy2 dx2, so you get absorption of light of two different wavelenghts anf hence two peaks.
What is tetragonal compression
if electrons are put into dx2-dy2 then electrons on x and y axis feel extra repulsion and move out along the x and y axis. Ligans on z axis feel less and move in a bit, so you get 4 long and 2 short bonds.
dxy and dx2-dy2 move down in energy as they are stabilised.
What is tetragonal elongation
putting electrons in dz2 means elctrons in the z axis are repelled and move out along axis. ligands on x and y aixs feel less and move in.
orbtials containing a z component are stabilised and move down in energy while the others are destablised.
what is jahn teller distortion
A molecule in a degenerate electronic state will undergo a geometrical distortion to remove the degeneracy
what is hydration energies
Enthalpy change for the reaction of a mole of gaseous M2+ with a infinite number of water molecules to give a hydrated cation.
How does the hydration energies change as you go across the period.
More exothermic beacause the size of the metal gets smaller so higher charge density so interaction gets stronger.
double humped curve. This is because water is a weak field ligand so all high spin except at d3 and d8.
How does the ionic radius change across the period
Gets smaller, d orbitals are occupied and are poor shidlders of nuclear charge.
Why are tetrahedral complexes favoured
6 bonds rather than 4 bonds. Delta oct is bigger than delta tet.
How to form tetrahedral complexes
large negatively charged weak field ligands
use 1st row metals
How to form sqaure planar complexes
Tendacy to form square planar increases as delta tet does. Pt and Pd will from sqaure planar to avoid filling the dx2-dy2.
How do you make complexes
By substitution reactions, replacing one ligand by another
What is the inner coordination sphere
Molecules attached to the metal
What is the outer coordination sphere
loosely bound molecules which surround the complex
What is aquation
replacing a ligand by water
what is anionation
neutral ligand is replaced by an anion
how can you influence which compound you crystalise
by changing counter ions
What does labile and inert mean
Labile - fast and rapid substitution
Inert- slow substitution eg mins,day or weeks
why are hexa aqua ions acidic
the metal is electropositive and take e density from O making the H more acidic.
What is the chelate effect
enhanced stability of complex containing chealting (polydentate) ligands over one similar monodentate ligand.
What is the main contribution to the chelate effect
is entropy as delta H should not change as it is the same metal.
what is the optimum ring number for Sp3 carbons
5 and 6
Name the irving williams series for M2+ and why are the more stable as the series goes along
Ba>Sr>Ca>Mg>Fe>Co>Ni>Cu>Zn
due to electrostatic effects and ligand field effects
what are hard acids
small non polarisble, highly charged metals. for example Al3+, Cr3+, Ti4+, VO2+
what are soft acids
larger, highly charged. Moslty in groups 2 and 3 and are cations of less electropositive metals
What are soft bases
large and more polarisable. most second row elements excpet for CO and CN.
What are hard bases
small and not polarisable. first row elements.
Give an example of when HSAB goes bad
Be2+ should be hardest cation and therefore be a hard acid but its small charge means its bery polarisable and distorts e clouds.
what is hydrometallurgy
seperate one metal from a mixture of metal ores using the methods of solvent extraction.
How are complexes used in detergents
Remove unwanted metal ions in hard water.
what is chealtion therapy
Remove unwanted toxix metal ions from the body without affecting the beneficial ones.
How does changing the Fe from high spin to low spin allows it to fit into the porphryin ring
High spin - the radius is too large to allow it to fit into the plane of porphyrin but low spin the radius is smaller and iron can fit into the plane. This cascade of conformational changes allows oxygen to bind.
How is cis platin made
The trans effect.
What is the trans effect
he trans effect is the labilization (making unstable) of ligands that are trans to certain other ligands
