Questions tagged [organometallic-compounds]

For questions relating to organic compounds which contain a bond between a carbon atom and a metal.

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21
votes
4answers
6k views

Why do Organolithium or Grignard reagents act as nucleophiles and not as bases with aldehydes and ketones

I've read entire Chapter 14: Organometallic Compounds of Francis Carey's "Organic Chemistry" but I still didn't get an answer to my question. Quote from the book: Because of their basicity ...
9
votes
2answers
12k views

Why can't the reaction of grignard reagent with carboxylic acid give a ketone?

I understand that a Grignard reagent can act both as a base and a nucleophile. It acts as a base in the presence of a proton source (eg: alcohols, amine, water, etc). But when reacting with a ketone ...
15
votes
1answer
4k views

Why do halogen-metal exchanges happen?

I'm trying to understand organometallic raegents but am stuck at halogen-metal exchanges. For example if you have $\ce{PhBr + BuLi}$ you get $\ce{PhLi + BuBr}$, I don't understand why $\ce{PhBu + ...
16
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3answers
20k views

Why do Magnesium and Lithium form *covalent* organometallic compounds?

Lithium and magnesium are Group 1 and Group 2 elements respectively. Elements of these groups are highly ionic, and I've never heard of them forming significantly covalent inorganic compounds. Yet ...
11
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1answer
1k views

Inorganic chemistry reaction mechanisms

Are there well developed reaction mechanisms in inorganic chemistry like those in organic chemistry? If yes, please suggest an easy to follow reference.
5
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1answer
5k views

What is the mechanism of formation of Grignard's Reagent?

What is the mechanism of formation of Grignard reagents? I couldn't find much in my book or on the Internet. This page says something which I am unable to understand. Why are the $2$ electrons in the $...
2
votes
2answers
6k views

Predicting bond-strength of metal carbonyls

The metal carbonyls (and similar organometallic compounds) involve a combination of sigma bond, a pi bond and backbonding. The bond strengths under consideration are the metal-carbon bond and the ...
6
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1answer
2k views

What makes R-MgX a more reactive Grignard reagent than R-Cu?

What makes $\ce{R-MgX}$ a more reactive Grignard reagent than $\ce{R-Cu}$? Has it to do with solvation, bond enthalpy, electronegativity?
5
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1answer
2k views

Why do Grignard reagents react with epoxides but not THF?

THF is used as a solvent for Grignard reagents, but epoxides react with Grignard reagents. There is only a small difference between epoxides and THF, what causes the difference in reactivity towards ...
4
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0answers
511 views

Sodium Naphthalenide

The sodium fusion test done in the lab for the systematic identification of a given organic compound is basically fusing sodium metal in a fusion tube, and then adding the compound in a small quantity,...
6
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1answer
2k views

Dissociation rates: trans-effect rule in square planar complexes

In lecture, the trans-effect was described. A ligand $L^t$ with a higher trans-effect as $L$ (cis to $L^t$) leads to a faster dissociation of ligand $L^d$ (trans to $L^t$). I would expect that the ...
13
votes
2answers
745 views

Do eta-4 benzene ligands participate in Diels Alder or other cycloadditions?

While refreshing myself on denticity to answer another question, I started to read about hapticity, which is the coordination of a ligand through multiple continuous atoms. A famous case is ferrocene (...
10
votes
1answer
130 views

How can the solid state structure of cyclopentadienyllithium be explained?

In the solid state, LiCp adopts a polymeric multidecker structure where Li atoms are sandwiched between two Cp rings (shown in this diagram from Organometallics 1997, 16 (17), 3855–3858): If we ...
5
votes
1answer
23k views

Reduction of alkyl halides to alkanes

For all the three parts, only methane has been given as the product in my textbook. In 1) and 2), according to the mechanism I wrote, I get both ethane and methane as products. I think both these ...
3
votes
1answer
2k views

Coordination number of carbon in methyllithium tetramer

According to J. D. Lee's Concise Inorganic Chemistry, the coordination number of carbon in $\ce{Li4(CH3)4}$ is $7$. But the structure of the tetramer is Doesn't carbon have coordination number $6$ ...
2
votes
1answer
6k views

Why does magnesium form covalent bonds with carbon?

According to my professor, magnesium and lithium form covalent bonds with carbon but calcium does not. He did not elaborate. Why is this so? The electronegativities are: Mg — 1.31 Li — 0.98 Ca — 1 ...
8
votes
1answer
209 views

Ketone/aldehyde synthesis from N-acylazetidines or aziridines

A common principle in organic chemistry is to make sure the product is less reactive than the starting material, to prevent overreaction. So, for example, the treatment of an ester with a Grignard ...
3
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1answer
1k views

Why are organolithium and organomagnesium compounds nucleophilic in nature?

My textbook doesn't say anything about this but does say that on addition of organolithium compounds to carbon dioxide, they give ketones and not carboxylic acids like grignard reagents. This has been ...
1
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2answers
1k views

Grignards do transmetallation?

Grignards don't add to alkyl halides to create linear carbon extensions because Grignards do transmetallation rather than SN2 displacement of halide. Is this correct? I thought transmetallation a) ...