inorganic (Benniston) Flashcards
What do Zinc enzymes do?
Alcohol dehydrogenase-
breakdown of ethanol to acetaldehyde.
What do Iron enzymes do?
Haemoglobin- transport of O2 .
What do Copper enzymes do?
Removal of superoxide O 2-.
What do Colbalt enzymes do?
vitamin B12 methylation
reactions.
Define transition metals.
Transition Metal- an element for which
an atom has an incomplete d-subshell or
which gives rise to a cation with an
incomplete d-subshell.
What are the names of the 5 d-orbitals?
dz^2
dx^2-dy^2
dxy
dxz
dxy
when would all of there orbitals be degenerate
when the metal is in it gaseous phase
why are the d orbitals not degenerate
dxy, dxz, dzy orbitals points inbetween the axis whereas dx^2 and dx^2-dy^2 is along the axis so when the ligands bind they will bind along the axis the dx^2-dy^2 and dx^2 will be higher in energy.
which orbitals are degenerate with each other
dxy, dxz, dyz are all degenerate with each other
dx^2 and dx^2-dy^2 are also degenerate with each other
What is the equation for learning number of d electrons
No. of d electrons = Group Number – Oxidation State
What is the first law of thermodynamics
Energy is conserved. It can be transferred from place to place and
converted between different forms, but the total energy of system +
surroundings is always the same
How is the first law of thermodynamics expressed for different systems
Total energy, also called internal energy has the symbol U
Isolated system: ∆U = 0
Closed system: ∆U = q + w
Physical Properties of d-block metals
- Most are hard, ductile and malleable with
*high electrical and thermal conductivities.
define ductile
Ability to be stretched or pressed into a shape without heating
define malleable
Ability to be shaped easily
without breaking
what are typical metal structures
hexagonal closed packed (hcp), cubic closed packed (ccp) or body centred cubic (bcc).
what are the exceptions of the typical metal structures
Mn, Zn, Cd and Hg
trends with metallic radii as you move across a period and why
gradual decrease in metallic radii as we move across the period the
effective nuclear charge increases so a high charge density with relatively similar amounts of shielding pulls electrons closer in the nucleus
what is Lanthanide Contraction and how does it work
the lanthanide contraction refers to the steady descrease in the size of the lanthanide series, this contraction occurs because the additional electrons are poorly shielded by the 4f electrons leading to an increase in effective nuclear charge and a decrease in atomic radius
which orbitals point along the axis and which point between them
dz^2 and dx^2-y^2 along axis
Dxz Dxy and Dyz point in between the axes
what are the assumptions for crystal field theory
- Ligands are point negative charges
- The binding withing a complex is purely ionic
- Metal ion is in the gas phase
- Bring the negatively charged ligands from infinity to generate the complex
outline the crystal field theory
1) the metal ion in the gas phase cannot sense the ligands. All 5 d orbitals have the same energy (degenerate)
2) use a thought experiment and start to move the ligand closer along the axis
3) when ligands get close but not bound all the d-orbitals sense the point negative charges, they all destabilise
4) attach the ligand
What happens to the orbitals in crystal field theory for an octahedral complex
1) As the ligands approach from infinity along the x,y and z axes the electrons in the d-orbitals start to sense them.
2) Since negative charges are being brought closer together the dz2 and dx2-y2 become destabilized and rise in energy +3/5 delta O
3) The other three orbitals are not so affected because they point in between the axes and lower in energy. -2/5 delta O
What happens to the orbitals in crystal field theory for an tetrahedral complex
Ligands do not point along any axis and now actually point between them
Now the three d-orbitals (dxy, dyz and dxz) are better aligned with the ligands and the other two (dz2, dx2-y2) point in between.
1: As the ligands approach from infinity in between the x,y and z axes the electrons in the d-orbitals start to sense them.
2: Since negative charges are being brought closer together the dxz, dyz and dxy become destabilized and rise in energy.
3: The other two orbitals are not so affected because they point along the axes and lower in energy.
4: The splitting term D(tet) is smaller than D(oct). The ratio is ~ D(tet) =4/9 x D(oct) for the same ligand type.
What happens to the orbitals in crystal field theory for an square planar complex
The two ligands along the z axis are pulled away from the metal - tetragonal distortion
1) As the two ligands along the z-axis are removed the d-orbitals with a z component lower in energy.
2) The ligands in the x-y plane are pulled in more and so d-orbitals with a x,y component rise in energy.
Eventually the two ligands are removed to infinity and the dz2 orbital falls in energy to below that of the dxy.
what is delta O
ligand field splitting
what is P
pairing energy, the energy required to pair electrons up in orbitals
what happens if P is larger than delta O
If the pairing energy is greater than delta o a weak field high spin complex is formed
what happens if delta O is greater than the pairing energy
If delta o is greater than the pairing energy then a strong field low spin complex is formed
what happens after d8 in terms of high/low spin
after d8 onward it makes no difference as the electron can only go in one place therefor the high/low spin notation is meaningless
how does the charge effect delta o
The value of ∆o increases with increasing charge on the metal ion.
define diamagnetic
all electrons are spin paired and complexes are repelled by a magnetic field.
define paramagnetic
complexes contain unpaired electrons and are attracted by magnetic fields.
what is the spin only formula and why is it useful
Measurement of effective magnetic moment is useful as it can distinguish between high/spin and low-spin and help determine coordination geometries
effective magnetic moment = square root of n(n+2)
where n is the number of unpaired electrons
Measured in Bohr magnetrons
define paramagnetism
the spins are randomly orientated in the material
what is ferromagnetism
Above a certain temperature (Tc-Curie temperature) the thermal energy is enough to overcome the alignment and normal paramagentic behavior prevails
define antiferromagnetism
the spins become aligned anti-parallel leading to a diamagnetic material
define ferrimagnetism
some spins are aligned anti-parallel to each other but overall there is a finite magnetic moment
what is the Jahn-teller effect
“If a ground-state electronic configuration of a non-linear complex is orbitally degenerate the complex will distort so as to remove the degeneracy and achieve a lower energy” - theory used to explain the distortion of octahedral and tetrahedral complexes
when would square planar complexes be more or less favored
less favored sterically especially for large ligands. Complexes are found for only a few metal ions and dominated by d8 transition metals (e.g., Ni2+, Pd2+ and Pt2+)
Need (i) Non-bulky ligands, (ii) Strong-field
ligands (i.e CN-).
why do complexes have color
Energy is required to move an electron from the t2g level to the eg level a certain frequency of light is required to promote the electron.Only a part of the white light continuum is of
the correct energy and so some of the light is
“left behind.” This gives a complex its colour.
What is the beer-lamber law
Amax = emax .c . l
A = absorbance
e = molar absorption coefficient dm^3mol^-1cm^-1
c = concentration
l = cell path length cm
Knowledge of the molar absorption coefficient is very useful as it gives some indication about how allowed a transition is
what are d-d transitions
a shifting of electrons between the lower energy d orbital to a higher energy d orbital by absorption of energy
what is laporte’s rule
If a system is centro-symmetric, transitions between states with the
same inversion symmetry (g → g, u → u) are
forbidden, but transitions between states of
different inversion symmetry (g → u, u → g)
are allowed.
what is the spin multiplicity rule
Transitions between
states with different spin multiplicities are
forbidden
what does gerade mean
gerade orbitals are symmetric meaning that inversion through the center leaves the orbital unchanged
which complexes are laporte forbidden
octahedral and square planar
how do laporte forbidden transitions occur
Laporte forbidden transitions occur as a result of distortions from centrosymmetry that occur continuously as the complex
vibrates. The vibration-induced breakdown of the Laporte Rule makes the d-d transitions
vibronically allowed
why are tetrahedral complexes laporte allowed
Tetrahedral complexes (Td) have no inversion symmetry
why is titanium good for construction
- excellent corrosion resistance
- high heat transfer efficiency
- good strength to weight ratio
how is titanium extracted and purified
the Kroll process-extraction from titanium ores
TiO 2 + 2C + 2Cl2 → TiCl4 + 2CO2
TiCl4 purified by distillation and then reduced back down to pure titanium
metal.
TiCl4 + 2Mg → Ti + 2MgCl2
how are titanium halides produced TiX4
All the TiX4 compounds can be prepared by the direct reaction of titanium with
halogen gas (X2 )
how can the TiX3 compounds be produced
The TiX3 compounds can also be prepared by the reduction of the corresponding TiX4
compound with H2 .
is TiCl4 a good lewis acid or base
lewis acid and forms adducts on on the reaction with lewis bases
how does solvolysis occur
solvolyis can occur if ionisable protons are present in the ligand
what are the most important oxidation stated of vanadium
+2, +3, +4, +5
+2 and +3 states are reduing
+4 - stable
+5 - slightly oxidising
what is the importance of vanadium +5 oxidation state
The only vanadium (+5) halide complex is VF5 which is a white solid and is based on a trigonal bipyramid in the gas phase.
what are the vanadium oxides
Oxides formed by vanadium are VO (+2), V2O3 (+3), V2O4 (+4) and V2O5 (+5)
what is the importance of V2O5
V2O5 is amphoteric (acts as an acid or base) and its aqueous chemistry is complex and
pH dependent.
how is chromium extracted
FeCr2O4 Chromite is also converted to Cr 2 O 3 which is reduced by aluminium or silicon:
how is CrX3 compounds produced
They can be prepared by reaction of Cr with X2 . When dissolved in water the ion, [Cr(H2 O)6 ] 3+ is produced
what colour [Cr(H2O)6] 3+
violet
what colour is [Cr(H2O)6]2+
sky - blue
How is manganese extracted
Pure manganese is prepared by reducing
MnO2 with Al in a blast furnace.
3MnO2 + 4Al → 3Mn + 2Al2O3
How is iron extracted
Iron is obtained from the oxide by heating it in a blast furnace in the presence of carbon monoxide.
Fe2O3 + 3CO → 2Fe + 3CO2
what is a common problem with materials containing iron and what is the reaction or this
A common problem with materials containing iron is the formation of ‘rust’ when
oxygen and water are present.
2Fe + O2 + 2H2O → 2Fe(OH)2
how is cobalt extracted
Cobalt extracted from its sulphide by conversion to the
oxide followed by reduction with H 2 or C.
2Co2O3 + 3C → 4Co + 3CO2
how are the cobalt dihalides produced
cobalt carbonate reacts with HX
CoCO3 +2HX = CoX2 +CO2 +H2O
how is nickel extracted
nickel occurs as NiS. the sulfides are roasted in air and converted to the oxides which are reduced to the metal by carbon in a smelter
what happens when NiCl2 is added to water
All the nickel (II) halides are known such a NiCl2 which when added to water forms the octahedral [Ni(OH2)6] 2Cl- complex which is green in colour.
what is the oxide of nickel
NiO
what are the coordination complexes of nickel like
The coordination complexes are dominated by nickel in the +II oxidation state. Complexes with NH3 , ethylene diamine are octahedral and blue in colour and paramagnetic. With a strong ligand such as CN - the square planar complex is formed. The square planar complexes are generally red, brown or yellow in colour and are diamagnetic. Nickel (III) complexes are less common.
how is copper extracted
Copper occurs as the ores CuFeS2 and Cu2S and CuS in the earth’s crust. Sulfide ores are concentrated and roasted in airSand is added to remove the iron as Fe2(SiO3) 3 and is removed.
what are the colours of the following copper oxides
copper + oxides are more stable than copper 2+
CuO - black solid
Cu2O - red solid
what are thhe coordination complexes of copper like
In the +I oxidation state the complexes are diamagnetic and colourless as a
consequence of the d 10 configuration.
The +II oxidation state is the most stable and common for copper. The d9
configuration means the complexes are paramagnetic and coloured. The ion,
[Cu(OH)6 ] 2+, is a distorted octahedron with two long Cu-OH 2 and four short Cu-OH 2
bonds (Jahn-Teller distortion)
why is anhydrous CuF2 and CuSO4 white
Anhydrous CuF 2 and CuSO 4 are white because the ligands are weak and do not cause a big ligand field splitting energy. Most other Cu(II) complexes are blue/green.
how is zinc extracted
Zinc occurs in the earth’s crust as ZnFeS, ZnS.
Extraction and purification is carried out by taking the sulphide to the oxide and reduction with carbon
what is the only oxide of zinc and what is the colour due to
The only oxide is ZnO which is yellow when hot and white when cold. Colour is not d-d
transition as there is a complete d shell- colour is due to defects in the solid
structure.
define barycentre
the energy before splitting
what is the CFSE for a d1 high spin complex
-0.4delta
what is the CFSE for a d2 high spin complex
-0.8 delta
what is the CFSE for a d3 high spin complex
-1.2 delta
what is the CFSE for a d4 high spin complex
-0.6 delta
what is the CFSE for a d5 high spin complex
no CFSE for high spin d5 complex
what is the CFSE for a d6 high spin complex
-0.4 delta
what is the CFSE for a d7 high spin complex
-0.8 delta
what is the CFSE for a d8 high spin complex
-1.2 delta
what is the CFSE for a d9 high spin complex
-0.6 delta
what is the CFSE for a d10 high spin complex
0 there is no CFSE
what is the CFSE for d1 to d3 low spin complexes
they are the same as the high spin cases
what is the CFSE for d4 low spin complex
-1.6delta + P
where p is the pairing energy
delta is likely large so there is a probable overall energy gain
what is the CFSE for d5 low spin complex
-2 detla + 2 P
as now there are 2 sets of paired electrons
what is the CFSE for d6 low spin complex
-2.4 delta + 2 p
as we start with one set
of paired electrons and end up with
three sets of paired electrons so one of the pairing energies will cancel
what is the CFSE for d7 low spin complex
-1.8 delta +p
now two of the pairing energies will cancel
what is the CFSE for d8 low spin complex
-1.2 delta as all of the pairing energies cancel
what is the CFSE for d9 low spin complex
-0.6 delta as all of the pairing energies cancel
what is the CFSE for d10 low spin complex
there is no CFSE for a d10 low spin complex
why are chromates and dichromates coloured
In [CrO4]2- and [Cr2O7]2- the metal ion is in the +6 oxidation state. Both are d0, therefore, no d-d transitions. Colour is because of process called charge transfer. Here, an electron from a filled π-orbital is transferred into the empty d orbital
What are the general observation in the d block
Up to Mn the maximum oxidation state = group number. Once d5 electronic configuration is exceeded high oxidation states are not observed. Metal complexes with high oxidation states for example MnO4- so Mn7+ are good oxidising agents
What is tetragonal distortion
The tetragonal distortion lengthens the bonds along the z-axis as the bonds in the x-y plane become shorter. This change lowers the overall energy, because the two electrons in the dz2 orbital go down in energy as the one electron in the dx2-y2 orbital goes up. Also causes the Dxy to go up in energy and the Dzy and Dxz to be lower in energy
Draw and energy level diagram for an octahedral complex
See images
Draw an energy level diagram for a tetrahedral complex
See images
Draw an energy level diagram for tetragonal distortion
See images
Draw an energy level diagram for a square planar complex
See image
What happens when paramagnetic species are very close together
When paramagnetic species are very close together ( i.e. bulk materials) or separated by a bridging species (i.e., oxides) that can transmit magnetic interactions, the metal centres may interact (couple) with each other.
Why would tetrahedral complexes be favoured
Tetrahedral complexes are favoured because ligands are as far apart as possible. This minimizes:
Electrostatic repulsion of charged ligands. Van-der Waals forces between large ligands.
Tetrahderal Complexes- large ligands e.g., Cl-, Br- and I- and small metal ions e.g., Zn2+, Co2+
What are the molar absorption coefficients between for Laporte forbidden transition
5-50 M-1cm-1
