18
votes
Bonding between rings and iron atom in ferrocene
The "real" structure of ferrocene is an iron atom sandwiched between two flat, parallel, pentagonal C5H5 rings. The diagram above shows the atomic positions from a crystal structure but the ...
- 35.1k
16
votes
Accepted
Negative oxidation states of Si
I am not sure if Silane ($\ce{SiH_4}$) can really be considered.
But there are silicides which silicon forms with strongly electropositive metals. In these compounds, silicon has a negative ...
- 723
16
votes
Accepted
Are there any significant uses of the compound formed by magnesium and anthracene?
It seems like an idea of using magnesium anthracene systems for the $\ce{MgH2}$ production persisted since 1980s [1] till late 2000s, when new more efficient method with better scalability for ...
- 37.3k
13
votes
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Why can't the reaction of grignard reagent with carboxylic acid give a ketone?
Huy Ngo says it all. A Grignard reageant will react first with just about any hydrogen that has even a modicum of proton donation capability, before "resorting" to the slower nucleophilic ...
- 51.1k
12
votes
What do these arrows mean in inorganic chemistry?
These are not arrows, but fragments of the molecule.
We suspect they are supposed to mean the allyl ligands.
This hardly qualifies as inorganic chemistry. Organometallic is probably the right word to ...
- 30.9k
11
votes
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Can ferrocene type sandwich compounds be made with fluorene?
Yes there are, many in fact. One of the examples is having a complex consisting of a fluorene molecule and of cp altogether with iron, described by Decken in Acta Cryst. E (doi: 10.1107/...
- 27.7k
11
votes
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Do organopolonium compounds exist?
As one might expect for an element with no long-lived isotopes, little is known about organopolonium compounds. What is known may be broadly divided into two categories [1,2; cited by Wikipedia]:
...
- 51.1k
10
votes
How does cyclopentadienyl anion act as reducing agent?
Disclaimer: None of this constitutes proof; it's just an informed guess. Any corrections with reputable sources are welcome.
The simplest proposal seems to be single-electron transfer (SET) from $\ce{...
- 70.8k
9
votes
Accepted
Does Grignard reagent on reaction with PbCl2 give PbR4 and not PbR2?
More is involved here than the simple nucleophilic exchange normally associated with Grignard reagents. Essentially, the proposed dialkyl lead disproportionates with displacement of metallic lead. ...
- 51.1k
8
votes
Accepted
Role of Cu in Corey-House synthesis
Copper is used to avoid lithium-halogen exchange. Additional information on that reaction can be found in this discussion. Organolithiums will often, instead of acting as a nucleophile, form a new ...
- 3,265
8
votes
Accepted
Is the term "heteroatom" reserved for exclusive elements?
The IUPAC Goldbook provides no 'official' definition of the term heteroatom,and as such you're somewhat free to use (and abuse) the term as you see fit.
Since no IUPAC definition exists, it may be ...
- 17k
8
votes
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What is the mechanism of this reaction?
Nicco: Of course you can't "see it". If you were given the correct structure, the solution to your post would be straightforward. There should be a double bond in the lactam ring as shown in compound ...
- 15.9k
7
votes
Coordination number of carbon in methyllithium tetramer
TL; DR: coordination number of carbon atom in methyllithium tetramer is indeed 7, arising from 6 intramolecular interactions, as you suggested, and an extra bond with the lithium atom of the next ...
- 37.3k
7
votes
Accepted
Ketone/aldehyde synthesis from N-acylazetidines or aziridines
I think your suggestion about the stability of the tetrahedral intermediate is correct, but it's not that the tetrahedral intermediate itself has stability. I think it's because the collapse of the ...
- 17.2k
7
votes
How to name this quintuply-bonded chromium dimer?
It was a great effort. However, in the proposed name
bis[(μ-2,6-{[2,6-di(1-methylethyl)]diphenyl}phenyl-1κC1,2κC7)chromium](5 Cr—Cr)
I can see several issues:
In you point 12: Forcing the ...
- 6,084
7
votes
Accepted
How does the Wurtz reaction produce alkynes?
@tox123: You have generated two radicals on the same carbon by a two-electron reductive α-elimination (1 --> 2). So far, so good. In other words, you have created a carbene (2). Carbenes can ...
- 15.9k
7
votes
Accepted
Why are tri-organotin chloride compounds so dangerous?
To get the gravity of how toxic organotin compounds can be, let us compare it with inorganic tin compounds. Most of the inorganotin compounds are non-toxic because of their low solubility and low ...
- 24.9k
6
votes
Why do the protons in pentacarbonylmethylmanganese show up at –0.21 ppm?
Unfortunately, you don't give an indication of what you expect the chemical shift for the -Me to be, other than higher than is observed. However, you are correct in your assumption; the π back ...
- 11.9k
6
votes
Is there a reaction between ethanol and aluminum?
The reaction of aluminum and ethanol forms aluminum triethoxide, $\ce{ Al(OC2H5)3}$, but the reaction is fairly slow at room temperature, particularly if the aluminum is anodized. In the presence of ...
- 29.6k
6
votes
Why do Organolithium or Grignard reagents act as nucleophiles and not as bases with aldehydes and ketones
Technically, you are comparing apples and oranges. Grignards and organolithium compounds are good nucleophiles (with the caveat permeakra highlighted) towards carbonyl groups. But they cannot attack ...
- 66.9k
6
votes
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Why are 3 equivalents of organolithium needed in synthesis of ketone from carboxylic acid?
The text box you are quoting from (p 219) refers to this specific reaction. The compound in question possesses an α-hydroxyl group, which needs to be deprotonated too.
Notice that three equivalents ...
- 70.8k
6
votes
Accepted
N-heterocyclic carbene metal complexes. Question about the delocalization of the nitrogen lone pairs
Some parts of this answer probably border a bit on personal opinion, but I will at least try to justify having such an opinion.
The first thing to do is to actually examine the heterocycle. What kind ...
- 17.2k
6
votes
Accepted
Will ferrocene undergo electrophilic aromatic substitution?
Due to the aromatic character of the cyclopentadienyl ligands, ferrocene can undergo electrophilic aromatic substitution reactions typical of aromatic compounds such as benzene. Ferrocene shows very ...
- 21.1k
6
votes
Effect of metal identity on CO bond length in carbonyl complexes
Let's look at the molecular orbital diagram calculated with JSmol.
As you know, the principal effect is back-donation from the metal to the π-antibonding orbitals of the carbon monoxide. But not all ...
- 51.1k
5
votes
Best reagents state for air free chemistry. Choosing halide for grignard synthesis
The chloride can be a bit slow to react, particularly if the aryl halide is hindered. You might need a small amount of iodine to get the reaction started. (Maybe you ran into this already?)
Once you ...
- 17.2k
5
votes
Reduction of alkyl halides to alkanes
Your answer for question #3 is correct. However, there is a fundamental misconception you used in #1 and #2 that led to an incorrect answer.
In your notes, it seems that electrons from the metal ($\...
- 1,331
5
votes
Do eta-4 benzene ligands participate in Diels Alder or other cycloadditions?
Coordinated benzene as a dienophile
It would be logical to suggest that an η4-benzene ligand could behave as a dienophile. The reason why benzene is characteristically unreactive, both as a ...
- 70.8k
5
votes
Accepted
Why does mercury in mercuric acetate have a lone pair?
TLDR:
Mercury in its (+2) salts does not have lone pairs readily accessible for covalent bonding. However, its 5d electrons do affect its properties, resulting in a relatively high polarisability.
...
- 21.3k
5
votes
Noyori hydrogenation and the Curtin–Hammett principle
There's no way to predict this.
Mnemonics are just rules, and rules are just rules. There will be exceptions, and you won't know when you should apply them a priori. If you could, it would be part of ...
- 17.2k
5
votes
Mechanism of a gold catalyzed addition to triple bond
In their 2005 The Journal of the American Chemical Society publication, Genêt, et al. have reported a gold-promoted cyclization reaction of bis-homopropagylic diols (see Graphical Abstract below), ...
- 39.1k
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