Skip to content
Home
About
Meet the Team
Join the team
Alumni
The Principal Investigator
Forschen in Singapur?
Research
Publications
Teaching
CM4212 – Main Group
CM4212 – TM OM
CM1111
Blog
Main Group OM
1. What is the bond order of M-Br-M bridges?
2.0
0.5
1.5
1.0
2. Bridged complexes form due to ...
change in concentration.
steric reasons.
both electronic and steric reasons.
electronic reasons.
Show answer
Bridges only form, when the complex fragments are electronically unsaturated. Electronically saturated complexes do not dimerize, etc. even if their ligands are small.
3. What is the bond order of M-H-M bridges?
1.0
0.5
1.5
2.0
4. Which reaction utilizes Grignard\'s reagent?
Mizoroki-Heck
Kumada-Corriu
Suzuki-Miyaura
Negishi
5. Which are the most reactive main-group organyls?
organolithium compounds
organomercury compounds
organozinc compounds
organomagnesium compounds
Show answer
Organolithium compounds are the most reactive in this series, because they have the highest bond polarity (most ionic bond-character).
6. Which ligands form the most stable bridges between metals?
alkyl
halido
alkoxido
hydrido
Show answer
Alkyl and hydrido bridges are electron-deficient, while alkoxido bridges are sterically less favorable.
7. Which reaction utilizes organozinc species?
Suzuki-Miyaura
Kumada-Corriu
Negeshi
Sonogashira
8. Which reaction utilizes organoboron species?
Mizoroki-Heck
Negishi
Kumada-Corriu
Suzuki-Miyaura
9. Many main-group organyls are ...
moisture sensitive
air stable
pyrophoric
water soluble
Show answer
Many main-group organyls are very strong bases which exothermically react with water (moisture sensitive). The heat released can ignite them (pyrophoric) and/or the organic solvent they are stored in.
10. Carbonyl complexes are favorably formed with low valent metal centers.
True
False
Show answer
Carbonyl ligands are good pi-acceptors. Low valent metal centers provide sufficient electron density for favorable pi-backbonding to bound carbonyl ligands.
11. Aggregation of organolithium compounds occurs preferably in ...
Non-polar, protic solvents
Polar, protic solvents
Non-polar, non-protic solvents
Polar, non-protic solvents
Show answer
Protic solvents decompose organolithium species (acid-base reaction), and polar solvents tend to break higher aggregates apart through coordination to the electron-deficient Li-centers.
12. Which of the statements is true?
Alkyl bridges are favored over hydrido bridges due to steric reasons.
Hydrido bridges are favored over alkyl bridges due to electronic reasons.
Alkyl bridges are favored over hydrido bridges due to electronic reasons.
Hydrido bridges are favored over alkyl bridges due to steric reasons.
Show answer
Alkyl- and hydrido-bridges are both electron-deficient (3c-2e). They only differ in their sterics, and bridges with smaller ligands (hydrido) are preferred.
13. Main group organyls react primarily as ...
Nucleophiles
Acids
Electrophiles
Bases
Show answer
They are essentially "stabilized" carbanions which due to the negative charge react as strong nucleophiles or bases.
14. Homoleptic carbonyl complexes exhibit only one CO band.
True
False
Show answer
The number of carbonyl bands depends on the number of unique carbonyl ligands, which in turn is influenced by geometry and symmetry.
Page 1 out of 1
