Transition metal chemistry Flashcards
topic 3
Transition metals
- hard, high melting solids
- conduct heat and electricity
- readily lose electrons to form stable cations
- variety of oxidation states available to most
- form a wide range of coordination compounds with different ligands and molecular geometrics centre on metal ions
- many are highly coloured and/or paramagnetic
Aufbau principle
electrons are added to the lowest energy orbital first
Hund’s rule
electrons fill empty orbitals before pairing and the unpaired electrons adopt the same spin values
Pauli exclusion principle
no two electrons may have the same set of quantum numbers (n, l, mI, ms)
groups 3 to 7 redox
highest oxidation state corresponds to group number
platinum metals - important in catalysis
- Ruthenium
- Osmium
- Iridium
- Palladium
- Platinum
- Rhodium
Form stable cations in water
d block ions
lost s electrons before d electrons
Mn2+ and Fe3+ are d5 ions
lower oxidation states what compound type
ionic
higher oxidation states what compound type
covalent
f-block/group 3/elements of the first transition series (not Cu) react with aqueous solution of acids to give what?
hydrogen gas and solutions of corresponding salts
Transition metals and halogens form?
anhydrous halides
anhydrous halides reaction from halogen and metal
2Fe + 3Cl2 –> 2FeCl3 iron (III) chloride
anhydrous halide reaction from metal halide and additional metal
Fe + 2FeCl3 –> 3FeCl2 iron (II) chloride
gives metal halide of lower oxidation state
Ox state of product of F + transition metal
highest possible
synthesis of aqueous sol of halides
react with salts of hydrohalic acids
NiCo3 + 2HF –> NiF2(aq) + H2O + CO2
nickel (II) fluoride
Co(OH)2 + 2HBr –> CoBr2(aq) + 2H2O
cobalt (II) bromide
Transition metal + acid
dissolves to halide salt and hydrogen gas
Mn + 2HCl –> MnCl2 +H2
Electronegativity and ox states
transition metals halides with low ox. states are more ionic
heavy d-block elements have significant covalent character
.
oxides and ox. state
low ox = ionic
high ox = covalent
Oxides and ph
low ox = basic
high ox = acids
Soluble hydroxide + aq sol of transition metal
gelatinous precipitate
sometimes the precipitate is a hydrated oxide (composed of metal ion, oxide ions and water of hydration)
transition metal salt + soluble carbonate salt
insoluble carbonate
carbonates + acids
metal salts, CO2 and H2O
Carbonates decompose on heating to form
transition metal oxides
coordinate covalent bond
donation of electrons from lewis base/ligand to lewis acid/central metal atom
Coordination bonding
secondary valence
secondary valence electrons don’t have to be bound to a charged species
Coordination compounds/werner complexes
ligands bond to a metal central atom
lewis acid
metal
lewis base
ligand
Common neutral ligands
water, ammonia, pyridine
common anionic ligands
cyanide, nitrate, carbonate, sulphate
monodentate ligands
connect with the central atom through one ligand
polydentate ligand
same ligand attaches multiple times at different points
chelation
polydentate ligands attaching to central atom
some bidentate ligands
ethylenediamine
macrocylic ligands
polydentate ligands in a ring
macrocycles in biological processes
used to immobilise metal ions and to increase their reactivity
naming coordination complexes
if ionic, name cation then anion
ligand first then central
ligands alphabetically
multiples of a ligand -> di/tri/tetra
if cation/neutral metal name is same with ox state at the end
if anion then add ate
lanthanides
silvery metals abundant
+3 oxidation states mainly
actinides
radioactive
+3 oxidation states mainly
only actinides in nature
thorium and uranium
condensed electron config of lanthanides
[noble gas] ns2 (n - 2)4fx (n - 1)d0
exceptions:
Ce, Gd and Lu have 5d1
crystal field theory
- Occurs for the d-orbitals of transition metals
- The metal ion and the ligand electron pairs are treated as point charges
- The interaction between them is purely electrostatic (ionic)
- If the ligand is charged: ion-ion interaction; if ligand is neutral: ion-dipole interaction
Porphyrins in biology
tetradentate macrocycle
metalloporphyrin e.g. haeme b
vital to life
colours of d0 and d10 transition metals
white solids
i.e. titanium (IV) oxide and copper (I) iodide
how does colour arise in partially filled transition metals
transition of element from t2g to 3g by UV light
relationship between value of delta-o and wavelength max
direct relationship for d1 metals
in Ti (III), delta-o = wavelength max
determining colour transmitted
opposite on colour wheel to whats absorbed
Ti (III) colour transmitted
violet
colour wheel nm
400, 430, 480, 560, 590, 630, 700
spectrochemical series
list of ligands based on the strength of their interactions with metal ions
strong field
high delta-o
low spin
shorter wavelength absorbed
CN
weak field
low delta-o
high spin
longer wavelength absorbed
H2O
F
