30 Questions
What type of chemistry deals with compounds containing metal–carbon bonds?
Organometallic chemistry
Which type of compounds are shown in Figure 13.1?
Sandwich compounds
What is a characteristic of cluster compounds as mentioned in the text?
May have ligands that bridge two or more metal atoms
According to the text, what is the bonding feature of carbide clusters?
Bonded to 5, 6, or more surrounding metals
What is the main focus of organometallic chemistry as conveyed in the text?
Compounds with metal–carbon bonds
What is the molecular orbital structure of CO in square-planar d complexes?
σ-donor and π-acceptor functions
How do CO complexes exhibit interactions with metal orbitals?
Strong frontier orbital donation and π acceptance
What does the lower energy of the C=O stretching band in IR spectra of CO complexes indicate?
Weaker bonds
In CO complex compounds, what causes the increase in C=O bond length?
Weakening of the bond
What effect does the presence of doubly bridging CO have on the C=O stretching band in IR spectra?
It decreases the band energy
What is the 18-electron rule based on in organometallic chemistry?
The number of valence electrons in the central metal atom
Which method considers each ligand as a donor of electron pairs to the metal, taking into account the charge on each ligand and the formal oxidation state of the metal?
The donor pair method
How is CO usually counted when determining electron count in organometallic chemistry?
As a σ donor primarily
What does a metal–metal single bond count as when determining electron count?
One electron per metal
What provides useful guidelines for understanding the electronic structure and stability of many organometallic complexes?
The 18-electron rule
Which of the following is the oldest known organometallic compound?
Zeise's salt
What is the notable feature of ferrocene?
Stable, planar structure
What is the most common ligand in organometallic chemistry after CO?
h5@C5H5 ligand
What type of compounds are Grignard reagents?
Complexes of magnesium and organic compounds
How are the number of bonding positions in organometallic compounds indicated?
By the Greek letter η followed by the number of atoms attached to the metal
What is the total valence electron count for [Fe(CO)4]2–?
18
How many valence electrons does [(η5–C5H5)2Co]+ possess?
16
What factor helps [Zn(en)3]2+ remain stable despite being a 22-electron species?
Weak antibonding effect of ethylenediamine
What determines whether complexes obey or violate the 18-electron rule?
Differences in ligand donor abilities
Which method is used for electron counting in organometallic chemistry?
Method A
What is the role of the bridging CO ligand in organometallic complexes?
Acting as a 2-electron donor overall
What happens to the Mo–Mo bond distance in organometallic complexes upon increasing the bond order from 1 to 3?
It shortens
What is the effect of nearly linear bridging carbonyls, such as those in [(h @C5H5)Mo(CO)3]2, upon heating?
They release CO upon heating
What leads to changes in the IR spectrum of organometallic complexes?
Interaction of metal d orbitals with CO p orbitals
What happens to the Mo–CO bond upon increasing the bond order from 1 to 3 in organometallic complexes?
It weakens
Study Notes
- Organometallic chemistry involves the interaction of metal atoms with a triply bridging CO ligand, which weakens the C=O bond further.
- The IR band for the C=O stretch is lower than in the doubly bridging case.
- In the doubly bridging CO mode, both metals can contribute electron density into CO p orbitals to weaken the C=O bond.
- Organometallic complexes can have a bridging CO ligand, acting as a 2-electron donor overall.
- The electron count for each Re atom in the complex is 5e, with a single electron donated to each metal.
- Nearly linear bridging carbonyls, such as those in [(h @C5H5)Mo(CO)3]2, release CO upon heating and react with it to form a product with an increased Mo–Mo bond order.
- The Mo–Mo bond distance shortens and the Mo–CO bond weakens upon increasing the bond order from 1 to 3.
- The interaction of metal d orbitals with CO p orbitals is an important factor in this reaction, leading to changes in the IR spectrum.
- The observed shifts in the IR bands are consistent with the changes in bond lengths and bond orders.
- The complex [(h @C5H5)Mo(CO)2-]2 undergoes a similar reaction when heated, with the Mo–Mo distance shortening and the Mo–CO bond weakening.
Test your knowledge of organometallic compounds and their nomenclature with this quiz, which includes identifying structures and understanding charge distribution.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
