L1 alkali metals organometallics Flashcards
What type of donors do hard M+ cations favour?
Hard donors (O,N)
Are the M+ cations of light elements hard or soft?
Very hard and polarising
eg. Li+, Na+
What is the bonding like for M+ cations?
Essentially ionic
What are M-L interactions like for M+ ions?
Quite weak
The complexes are labile and have rapid ligand exchange
What is the lability like as you move down group 1 M+?
Increases
What is the bonding like in R-M complexes?
Essentially ionic
How does ionic character change down a group?
It increases down the group
How does electropositive character change down a group?
Increases
How does ionic character change with s-character of the carbon atom?
Ionic character increases with increased s-character
What is aggregation?
Formation of M+ ion clusters
Why is aggregation common?
It allows for higher coordination number of M+ to be achieved
What factors affect aggregation?
M+ size Steric demands of R- Solvation + presence of donors Temp Concentration Solvent
How does M+ size affect aggregation?
Larger M+ require higher coordination number and have a greater tendency to aggregate
How do the steric demands of R- affect aggregation?
Larger R- blocks coordination sites which lower the aggregation state
What is the effect of solvation on aggregation?
There is competition between aggregation and solvation (presence of donors)
Donors disfavour aggregation
How does temperature affect aggregation?
Higher temperatures favour disaggregation
How does concentration affect aggregation?
Higher conc favours aggregation
How does solvent affect aggregation?
Strong donors favour disaggregation
