Chemistry Chapter 4.1 Transition Metals Flashcards
What is the electron configuration of first row transition metal atoms?
[Ar]3d^n 4s^2
What are the exceptions to the electron configuration of the first row transition metals?
Chromium - [Ar] 2d^5 4s^1
Copper - [3d^10 4s^1
What are the post-lanthanide elements? What is their core electron configuration?
Hf-Hg – [Xe]4f^14
What is different about the bonding electrons for the first transition series (elements in the first row of the d-block)?
the electrons in 4s and 3d orbitals can take part in the formation of chemical compounds (not just the highest principal quantum number like the s and p block elements)
What are oxidation states?
The state of an atom when it loses or gains electrons when chemically bonded
What are the implications of unusual ground state electronic configurations?
useful properties or redox reactions
How does an electron move through the electron transport chain in photosynthesis?
passes electron from one molecule to the next changing oxidation states
How do transition metals turn into complexes?
binding with LIGANDS
What is a ligand?
molecule or ion (neutral or anionic) that bonds to a transition mental centre forming a complex
What is a Lewis base?
any substance that can donate a pair of nonbonding electrons
How does a ligand act as a Lewis base?
donates a lone pair to an oxidized transition metal in a complex
What type of bond is between a ligand and a central transition metal ion?
part ionic character (electrostatic attraction between the central metal cation and the NEGATIVE REGIONS of the POLAR ligand molecules) and part polar covalent character (lone pair sharing between ligand and metal centre)
What is a monodentate ligand?
a ligand that has one donor atom
–> NH3 –> N
–> H2O –> O
–> Cl- –> Cl
–> OH- –> O
–> CN- –> N
What is a bidentate ligand?
a ligand that has two donor atoms
–> H2NCH2CH2NH2 –> N+N
C2O4 2- –> C+O
What type of ligand is EDTA?
hexadentate
–> donates with 2 O and 4 N
ethlenediaminetetraacetate
What are polydentate ligands?
more that two potential donor atoms (not all atoms have to be used)
- sometimes represented as only the donor atoms bonded to metal centre)
What is a chelating ligand?
two or more donor atoms of the same ligand are bound to the same central metal - strong bond
What is a bridging ligand? When does it occur?
different donor atoms of the same ligand are bound to different central metal ions. occurs when there are many metal ions in the area
What is a terminal ligand? When does it occur?
one donor atom from a polydentate ligand is bound to one central metal ion. occurs when the central metal ion is already bound to other ligands
What is an ambidentate ligand?
have more than one possible donor atom but only one can be used at a time
Why do ambidentate ligands occur?
charge, resonance, position of electron, space available
What does ambidentate ligands cause?
isomerism
How do the different bonding possibilities of ambidentate ligands compare in molecular formula and molecular shape?
same molecular formula; atoms are connected differently –> linkage isomers
How can you write the formula of a coordination complex?
complex placed in brackets and counterions (not part of complex) are outside
What are counter ions used for? Do they have to be used?
used to balance out charge of complex
–> complexes can also be used to counter the charge
What are coordination isomers?
pairs of complexes that differ by which metal is the cation/anion
–> ligands swap (coordinated with different metals)
–> only works for salts where the cation and anion are complex ions
What are isomers?
molecules have the same composition/molecular formula but may not be the same substance because of different connectivity/bonding
What is linkage isomers? What type of isomerism is it?
two ligands are the same but are bonded at different locations (different donor atoms used to bond to central metal)
– type of constitutional isomer (structural isomer)
What is ionization isomerism? What type of isomerism is it?
differ by which anions are coordinated and ones which are not
–counter ion outside of coordination sphere and coordinated ions inside the coordination sphere swap
- type of constitutional isomer because it is the same molecular formula but the connectivity is different
What is a constitutional isomer?
same molecular formulas, but different connectivities/bonding
What do the properties of transition metal complexes depend on?
coordination number and stereochemistry (how coordinated atoms are arranged in space)
What is a coordination number?
Number of donor atoms bonded to central metal
What is the stereochemistry of a coordination number of 2?
usually linear
What is the stereochemistry of a coordination number of 3?
usually trigonal planar
What is the stereochemistry of a coordination number of 4?
tetrahedral or square planar
What is stereoisomerism?
different, non-interconverting spatial arrangements
In which coordination number does stereoisomerism begin occurring?
coordination #4
When are complexes cationic?
neutral ligands (metal is cationic)
When are complexes anionic?
anionic ligands
What is a cis isomer? What is a trans isomer?
cis same substituent is 90 degrees
trans = same substituent is 180 degrees
–> coordination 4 and 6
What is the stereochemistry of coordination number 5?
square pyramidal or trigonal bipyramidal
What is the stereochemistry of coordination number 6?
octahedral or distorted octahedral
What types of isomerism occur in the octahedral stereochemistry?
cis and trans when there are 4 of one substituents and 2 of the other substituents
fac and mer when there are 3 of each type of substituent
What are the fac and mer isomerisms?
fac - two equatorial and one axial
mer - both axial and one equatorial
What us the metal carbonyl complex?
ligand are carbon monoxide molecules (CO)
What is a hemoglobin?
tetrameric protein containing 4 heme groups (4 ligand porphine and central metal Fe)
– transports oxygen from lungs to the rest of the body
