Organometallic Synthesis - Science topic

Yes of course

Dear Eric Täuscher here is another interesting paper by the famous henry Gilman entitled "Color Tests for Some Organolithium Compounds"

Thank you Frank T. Edelmann

Indeed I used 15 years ago meta orto and para. dicarbadodecaborane

However I used as a powder precursor and I got a lot of C within the films. I will try it in toluene

Dichloromethane..

You may find an answer here:

Magnesium ethoxide, once formed then it will not give any color (as you mentioned), even keeping the same in open atomosphere.If you can eleoberate the reaction then more chemistry can be thought upon.

If you are trying to prepare by reacting of magnesium metal with ethanol in the presence of some initiator like iodine then the reaction will start and will complete at higher temperature and if the moisture content is at higher side in the used ethanol then reaction will take more time for completion and if the moisture is very high then reaction will not proceed further and can not be completed even at higher temperature.

what method do you suggest? I attempted to separate on a silica column but the complex was not collected

thanks for your answer d.merola, the solvent was n-decane and the molar ratio of the reaction was (1:1), so there is no excess of ligand.

Thank Hyun-Sue! Do you have any idea about the etching rate of each metal?

You can by choosen strong  ligand more than ammine

You're reducing the Cu, what about starting from 4-formyl benzoic acid? if you make the reaction ie 4-amino aniline, you'll have the schiff bases which can be easily reduced to the amine group, those are very stable with copper in different solutions. Be sure to protect the acid group at the beginning. 

I have found something more later (see links below).

Kamel Landolsi, for Co(II) and Cu(II) NMR spectroscopy is not suitable since they are paramagnetic species (7 and 9 d-electrons). 

I always caution people not to base too much on color.  It may appear green but not be CrBr3 - do you have any other analysis to suggest that is what you have?  Have you tried recrystallizing to see if you have any of your desired material left? The original Collman paper indicated it should be washed with a number of reagents, some of which will eliminate any excess NBS which is probably your biggest problem.  Finally, that paper also indicated that acetic acid as solvent was important - is that what you used?

Thank you everyone

Brahim, do you have access to Google Scholar?  That is just a subset of the normal Google search engine that you can access by searching for "Google Scholar" and selecting it.  If you type copper(I) pyrazine complex" into it, you will see quite a few papers, but most of them deal with things like pyrazine carboxylic acid to make coordination polymers (MOFS).  The best that you can do is compare bond lengths in those compounds but there will be no energy comparisons since they are very different compounds.

OK, thank you very much for your answer :)

Using Zn/HCl, Fe, Sn and other heavy metals as redusing agents in the case of nitroimidazoles offen makes a problems because this metals in molar quantity can form comlex with imidazole moiety. It is better to use catalitic ammounts of active metal and perform the redution in athoshere of hydrogen. The best systems is H2/Ni(Raney) or H2/Pd(on activated carbon). This reactions does not requer high temperature and generally can go under atmospheric pressure. But the equipment and the solvents (methanol or THF) have to be VERY pure, espesially witout any traces of S(II)  compounds, because such catalist can be very easily poisoned

Hi Mr. Abanoub M. Abdallah

There is the only best way to get a single crystal of org or metal complex is TRY UNTIL YOU GET IT. But there are some tips: Make sure that your complex is pure, Keep dilute solution for crystallization, maintain constant room temperature, probably 20 degree C is good, Make sure that there is no vibration around crystallization place...... From my experience, Crystallization techniques for metal complex is Slow evaporation and Vapour diffusion method. If your complex soluble in wayer, better use water as solvent or mixture of solvents like MeCN-H2O or acetone-H2O

All the best  

thankyou for your answer

Dear Ramasamy Raj Kumar

Kindly find this paper of your interest....

Journal of Coordination Chemistry, 2015

Regards

Many reactions going well with absolute ethanol.

Not exactly. one reason of poor adhesion can be the oxide layer formation on the platinum surface.

Yes, but we would need more info to help with specifics. Solvent selection can play a role, and you can also add additives that react with products, thus shifting the equilibrium via Le Chatlier's principle. 

Nadeem, if you could let me know which substrate you are planning to use, I think I would be able to give you more precise advice concerning the conditions - I was among those who have developed these reagents. it depends a lot on whether you take bromide or iodide and is your substrate a heterocycle or a usual arene.

Dear Ahmed,

better to use anhydrous Fe salt for complexing with shiffbase ligand.

Thanks for this hint - nevertheless it is more or less the original ICON program. The Anderson modification includes atom-atom repulsion terms, allowing for geometry-optimization.

Hi - I guess you are learning to work with nickel- the answer of course is that it's quite easy. If you need any advice for coordination chemistry; the tricks the professions use then just ask, best wishes, Ian.

There is actually no syntheis described for tetrakis-(iodophenyl) borate.

But you can try Grignard-Reaction of 1,4-diiodobenzene with Sodium tetrafluoroborate.

A 3-necked, 5000 mL round bottom flask equipped with a magnetic stirrer, thermocouple, nitrogen bubbler, and addition funnel was charged with magnesium turnings (12 g, 0.49 mol) and 500 mL ether. 1,4-dibromobenzene (114 g, 0.48 mol) was dissolved in 500 mL ether and placed in the addition funnel. About 175 mL of the solution was added, but no increase in temperature was seen. About 0.4 mL of 1,2 dibromoethane was added to initiate the reaction. The reaction was then heated to reflux and the temperature seemed to remain constant at 35° C. The rest of the 1,4-dibromobenzene solution was added slowly dropwise and the mixture was allowed to reflux for 30 minutes after the full addition was complete. The mixture was allowed to cool to room temperature once the reaction was complete. The mixture is used without purification or isolation for further reactions.

Sodium tetrakis(4-chlorophenyl)borate (2c; CAS 14644-80-5)

1,2-Dibromoethane (70 μL, 0.81 mmol) was added to a suspension of Mg turnings (1.62

g, 66.6 mmol) in Et2O (10 mL) and the mixture was stirred at room temperature until bubbles

were observed. A solution of 4-bromochlorobenzene (10.6 g, 55.4 mmol) in Et2O (55 mL)

was added to it slowly over 30 min, and the resulting mixture was further stirred for 1 h.

S4

Sodium tetrafluoroborate (1.11 g, 10.1 mmol) was then added to it, and the mixture was

stirred for 32 h at room temperature. The reaction mixture was poured into a solution of

Na2CO3 (25 g) in water (250 mL), and this was stirred for 10 min at room temperature. The

precipitate was filtered off through celite and the phases were separated. The aqueous layer

was extracted with Et2O and the combined organic layer was dried over Na2SO4, filtered, and

concentrated under vacuum. The residue was triturated with CHCl3, washed with

CHCl3/hexane, and dried under vacuum to afford sodium tetrakis(4-chlorophenyl)borate as a

white solid (2.87 g, 5.98 mmol; 59% yield).

Nadeem, check out the following URL: https://www.reddit.com/r/chemistry/comments/31vhpo/how_do_you_verify_how_much_grignard_reagent_you/

Essentially, you can use a small sample of your solution and titrate it.

The most reliable synthesis doesn't use formaldehyde. Combine 23 g PPh3 and 3g RuCl3xH2O in 350 mL of 2-methoxyethanol and reflux overnight. Allow to cool for an hour or so with stirring then filter under air on a sintered funnel. Wash well with ethanol and then petrol and air dry. The product should be about 9 g and may be pale pink or yellow - either is fine. They are different crystal forms of the same complex and so depending on the relative amounts you may get different proportions of the CO band in the solid state IR - not an issue so far as subsequent reactivity. 

The most likely culprits in the formaldehyde approach are either Ru(CO)3(PPh3)2 (substitution inert) or RuH2(CO)(PPh3)3 which also doesn't have particularly labile phosphines. Sadly, all have IR bands in more or less the same region (ca 1910) so you would need 31P NMR to actually check what you have.

Lanl2dz is best as a basis set. One should also add ECP for the same.

I expect that starting with the hexacarbonyl (WCO6, MoCO6) you could react with the olefin. PK Baker wrote several papers describing the formation of W(CO)3(NCMe)3 (72 h reflux in acetonitrile) then react at ice temperature with iodine to obtain the 7 coordinate WI2(CO)3(NCMe)2 complex. MM Meeham and Baker then reported reacting this complex with various olefins, including the one you described to obtain a complex similar to your target. Baker was my original PhD supervisor and wrote many papers in this area.

You could try other solvents (e.g., toluene) and higher starting temperature. You could also try different orders of addition: mixing the ligand precursor with the ruthenium complex first and then add KHMDS. Overall, I would especially recommend that you try another ruthenium starting complex such as the so-called Hoveyda 1st gen catalyst. 

First, please don't call a compound of Hg and S "organometallic" This term is confined to compounds with a direct metal-carbon bond. Naturally a Hg-S compound cannot be "organometallic".

Second, Hg and S can form HgS which has two forms. The red form, known as cinnabar, has a polymeric zigzac chain structure: ... -Hg-S-Hg-S-Hg-S-... with covalent Hg-S bonds with a 236 pm Hg-S bond length. The black form which is metastable, exhibits the sphalerite (zinc blende) structure. The interactions between Hg and S are a bit more ionic in this case. Since the most stable form of HgS is red, the black form is unstable and Hg2S does not exist,  I don't believe that you produce mercury sulfide by this procedure.

Furthermore, the black material you are producing is presumably not even a pure compound, but a mixture of things (Michael is probably very right in this point). Therefore, you cannot seriously discuss "the bond structure". You should first try to determine the different species which occur in this mixture.

Personally, I would guess that the material contains largely elemental Hg in finely divided particles. Most of real mercury compounds such as kalomel Hg2Cl2, HgCl2, HgS (there is no Hg2S or HgS2), HgO are NOT black, many of them are colourless, yellow or red. Hg in elemental form is black.

may u can reduce N=C then prepare a complex and compare with once in present of double bond

Hi James!

Yes, they are different. However, I know that it can be done as I think I have synthesised the complex but as a powder and not as a good crystal. That was done.with another similar method.

All is in Gaussian manual. In this case you need to specify (Root=4) while repeating excited state calculations. With this switch Gaussian will treat 4th exited state as one to optimize. It will not guarantee success though since during optimization energy may change significantly so at the end you get something else.

This is a hard question to answer because so many factors could be at play when it comes to synthesis of MOF crystals. Under the assumption that these results you have seen repetitively (i.e., over multiple trials). I have but one question for you.

You have to ask yourself what are all those -OH doing?  Most likely they are terminating the surfaces of the MOF particle (Zn-OH terminating sites) which will actually encourage aggregration between two or more MOF particles. TEA does not generate -OH ions and hence you have smaller particles due to less or no aggregration (aggregration is encouraged by polar ends on a MOF surface).

At least that's what I can think of. May not necessarily be the case

Btw,

What was the yield and purity for your synthesis in TEA in comparison to your NaOH synthesis "XRD shows the product is pure ZIF-8 with high yield(65% for Zn:Hmim:NaOH= 1:4:1 and nearly 100% for 1:4:2)." ?

Hi Eric, I am not actually trying to obtain epoxide rather I am getting Michael adduct. 

No matter, the change of solvent done a trick for me. I got 51:49 ratio for R and S respectively. 

Thanks for your answers!!!

Dear Maolong,

Please see follow papers:

1. Masoud Mirzaei , V. Lippolis , Hossein Eshtiagh Hosseini , milad mahjoobizadeh , Decaaquabis(μ3-4-hydroxypyridine-2,6-dicarboxylato)bis(4-hydroxypyridine-2,6-dicarboxylato)tetramanganese(II) 3.34-hydrate: a new three-dimensional open metal-organic framework based on a tetranuclear MnII complex of chelidamic acid and undecameric stitching water clusters , Acta Crystallographica Section C: Structural Chemistry , Volume ( 68 ) , 2011-12, Pages 7-11.

2. Masoud Mirzaei Shahrabi , H. Aghabozorg , Hossein Eshtiagh Hosseini , A Brief Review on Structural Concepts of Novel Supramolecular Proton Transfer Compounds and Their Metal Complexes Part(II) , Journal of the Iranian Chemical Society , Volume ( 8 ) , 2011-4, Pages 580-607.

For further papers on di-carboxylic acid transition metal complexes go to this link:

The reference you have provided describes addition of AlkLi to diazabutadiene, not  the metalation. So how you have tried to lithiate? How you wanted to trap the lithiated compound? For these substrate you probably use LDA or LHMDS, as any alkyllithium will give the product of a nucleophilic attack. Most probably,  the lithiation reagent abstracts proton(s) from the methyl groups. Such anion will behave like a deprotonated ketone, differently compared to the typical reactivity of vinyl- or alkyllithium compounds.

Electrochemistry (e.g. cyclic voltammetry) can help you to study some of these properties and stability but sometimes it is not easy to clearly explain results (for some metal complexes can be found studies which operate with different coordination number on central atom). At least there can be obtained information how many kinds of iron (means how many different bonding situations) are present under some conditions in solution and how it changes by addition of other species (or with changing conditions - pH, temperature). It can be studied in situ ofcourse. Coordination can change in solution according to different pH (or other conditions) and this can completly differ from solid state. For pure species, the determination of ratio of Fe mass to organic mass can give you clearly the formation about geometry but I suppose in this case is the ratio given exactly and you are only not sure about interactions. Don't forget that dimeric species (two nuclear) or even more complicated (nonstable) complexes can be formed in solution too. What about color and changes of color under different conditions? Did you try some spectral analysis (UV, VIS)? Maybe some kind of titration and slight changes in titration curves can show you the difference in coordinated/noncoordinated acidic groups too.

 Dear Dr. Kevin,

Please see my RG page. I suggest that ATRC/ATRA reactions are excellent objects for Redox/Organometallic chemistry. 

Hi Ramin,

The main problem is that one can hardly suggest you a solvent for a compound, having no idea about its structure.

As far as I remember you were going to synthesize a metal complex of tetraphenylporphyrin (TPP), although you didn't specify what is the metal ion.

If this is the case, then the problem with the solubility of the product and by-product could be expected from the very beginning.

In fact, you may not find a "good" solvent for this compound. Try benzonitrile under heating. But the best solution is to use a porphyrin with higher solubility, then TPP, e.g. the one containg alkyl groups in the aryl.

By the way it is not clear, why you think the crystalline material is a by-product. It could be a portion of your product, which crystallizes from the reaction mixture.

There are several excellent reviews out there that you can use to find the specific references for the syntheses. For example: http://www.sciencedirect.com/science/article/pii/S0032959203002589

Hi Rajbinder, 

So your compound precipitates in methanol, which is convenient for collecting your product, but not so convenient for running reactions, am I understanding correctly? One resource that I really like using when I'm in a problem like this is this polarity chart. You've probably already seen this, so I apologize if I'm just stating the obvious to you. <http://www.pallavchemicals.com/images/Tech_Center/Solvent%20Miscibility%20Chart.png> Since you're dealing with a peptide, I would assume you would have to deal with solvents that can dissolve amides. It's unfortunate that DMF didn't work, that's the first solvent I would have recommended. Would it be safe to heat your compound in DMF to induce solubility? Or is your metal conjugate too unstable to withstand that kind of energy? In other words, does it need to be kept at a low temperature? When nothing seems to work, and it's safe to do so, heating helps. And in fact, a lot of the reactions I am running depend on the temperature of my solvent. It is convenient, because your starting material will precipitate out when you cool down again, making work up a little easier. A little more information about your reaction conditions would help me answer more helpfully. 

Hope this helps.

Good luck!

Diana 

You should check the composition of the complex. Regardless of the stoichiometry, is not usually the Co (III) complexes are five coordinated. They are typically octahedral.

I would prefer to add the benzaldehyd in solution (dry Ether) to the freshly prepared Grignard reagent slowly (over 1h or longer) at 0°C. In this way the benzaldehyde is always present in very low concentrations.

Formaldehyde is too reactive and so are the imines formed with it. Most methaneimines will either give cyclic trimers or undergo further transformations. Actually, I can't remember any example of stable methaneimine, regardless of the substituent at nitrogen. May be you should try other aldehyde. Also, don't be too wary about the Boc-group - it can survive mildly acidic conditions.

Hi Mer Mercurate

Well there are a lot if things to compare, the first thing is the geometry, they have different geometries where Ir is octahedral while Pt is square planar 

secondly is the solubility, Ir complexes are more soluble and easier to prepare and the synthetic procedures are very well known while for Pt special conditions should be obeyed

third, the quantum yields where cyclomatalated Ir complexes have very high quantum yields probably more than 50% and can reach 100 % (contrary to Pt) and modifying the ligands or substituents you can fullfil all the emission spectra from the blue to green to red to NIR 

fourth, is the stability, Ir complexes can be air and water stable where most of Pt complexes are not and for cyclometalated Pt complexe, Pt(II) complexes can be easily oxidized to Pt(IV) mainly in chlorinated solvents such as DCM or chloroform and thus sometimes you quinch the emission 

and the last thing I want to comment is due to these properties of Ir, it is taking a great interest nowadays in NLO measurements (non linear optics) where very interesting results have been published 

Coupling aryl iodides with sulfur source to form thiol phenol try the reaction with sodium sulphide.

Make the Pt(DMSO)2Cl2 complex first, its easy to make just put PtCl2 into DMSO and you get the complex out as long needles almost immediately. You can collect them via filtration. Then react this complex with your ligand.  The ligated DMSO will be replaced first.

Yes.

The NdFeB magnets are the strongest magnets available. Up to +150 degrees C, they are stronger than the other Rare Earth magnet, SmCo. At around +150 degrees C and above these Neo magnets perform not as strongly as SmCo. The maximum recommended temperature for the NdFeB magnets is +230 degrees C, whereas the SmCo can work at +300 to +350 degrees C.

NdFeB can be used at low temperature but at around 135 Kelvin (-138 degrees C), the direction of magnetisation is said to change from a single axis (easy-axis) to an easy-cone which could cause a fall in output of up to 15% due to this spin reorientation. It is possible to use Neodymium Iron Boron magnets to be used at even colder temperatures but this drop in output will need to be taken into account.

The temperature coefficient of Intrinsic Coercivity (how Hci varies with temperature), b, for Neodymium is approximately -0.6%/degree C (from ambient, but a range of -0.45%/degree C to -0.6%/degree C is possible depending on the Neodymium grade) between +20 and +120 degrees C.

The temperature coefficient of Remanent Induction (how Br varies with temperature), a, for Neodymium is -0.12%/degree C (from ambient, but a range of -0.08%/degree C to -0.12%/degree C is possible depending on the Neodymium grade).

Reference: http://www.ndfeb-info.com/temperature_ratings.aspx

It is only a feeling but I think this compound is probably tetrahedral. This feeling comes from an attempt when we tried to determine the X-ray structure of an analogous Pd(0) compound, Pd(BDPP)2 (BDPP = chiral 2,4-bis-(diphenylphosphino)pentane). A square planar structure was out of question, while with the tetrahedral we came very close to the solution. Probably, we did not play long enough with the chelate conformation then.

PhINTs is soluble in ethanol, DMF, Dichloromethane etc.

To remove water you can use either Dicyclohexylcarbodiimide(DCC) or Ethylene glycol

Schiff bases can be prepared by reacting alpha halogenated  ketone with Amines using either base or acid catalysts under refluxing condition followed by cooling to get  the desired product

Hello Enrico,

Yes. We have worked with such reactions. Many references are also available on Pd catalyzed decarboxylative couplings. Simple thumb-rule is that you will need elevated temperature to cleave CO₂ with ease. I have tried many such reactions in MW, and it works even better.

I've coupled amine hydrochlorides and acid chlorides by adding an excess of triethylamine (~2.5 equiv) in CHCl3 and heating.  

I've made it in a drybox in one step from Ni(COD)2, PPh3 and PhCl.  It was yellow all of the times I made it (maybe 3 or 4 times).  That is one way to avoid isolating Ni(PPh3)4.

The napthyl analog is air- and water stable.  It can be made from NiCl2/PPh3/reducing agent/NapCl.  I haven't made it myself, but one of my former coworkers did.  It can also be purchased from Aldrich.

You can  check the solubility of your complex in deuteriated solvent . If soluble in CdCl3 which will be good solvent or Deuteriated acetone

which cmpos are you targetting?

The previous answers are correct, but if you want a complete understanding, please read:

WATER AND PROTON EXCHANGE PROCESSES ON METAL IONS

LOTHAR HELM, GAE¨ LLE M. NICOLLE and ANDRE´ E. MERBACH

ADVANCES IN INORGANIC CHEMISTRY

2005 Elsevier Inc.

VOLUME 57 ISSN 0898-8838 / DOI 10.1016/S0898-8838(05)57007-7

Hi,

Some papers that might help.

 

Bill

 

Pd/C: an efficient and heterogeneous protocol for oxidative carbonylation of diols to cyclic carbonate

By Chavan, Sujit P.; Bhanage, Bhalchandra M.

From Tetrahedron Letters (2014), 55(6), 1199-1202. DOI:10.1016/j.tetlet.2013.12.116

The present protocol involves highly efficient and practical approach for the synthesis of cyclic carbonate via oxidative carbonylation of diols, glycerol, and its derivs. using Pd/C as a heterogeneous, inexpensive, and recyclable catalyst. The effect of various reaction parameters, such as solvent, base, time, and temp. was investigated and applied for the synthesis of value added cyclic carbonates in a good to excellent yield within shorter reaction time. The developed catalytic system circumvents the use of ligand and dehydrating agent with an addnl. advantage of palladium catalyst recovery and reuse for up to four consecutive cycles.

Cited 0

Scope and mechanism of the PdII-catalyzed arylation/carboalkoxylation of unactivated olefins with indoles

By Liu, Cong; Widenhoefer, Ross A.

From Chemistry - A European Journal (2006), 12(8), 2371-2382. DOI:10.1002/chem.200500787

Treatment of 1-methyl-2-(4-pentenyl)indole (5) with a catalytic amt. of [PdCl2 (MeCN)2] (2; 5 mol %) and a stoichiometric amt. of CuCl2 (3 equiv) in methanol under CO (1 atm) at room temp. for 30 min gives Me (9-methyl-1,2,3,4-tetrahydro-4-carbazolyl)acetate (6), which was isolated in 83 % yield. A no. of 2- and 3-alkenyl indoles undergo a similar palladium-catalyzed cyclization/carboalkoxylation to give the corresponding polycyclic indole derivs. in moderate to excellent yields with excellent regio- and diastereoselectivity. Under similar conditions, vinyl arenes undergo intermol. arylation/carboalkoxylation with indoles to give 3-(1-aryl-2-carbomethoxyethyl) indoles in moderate yield with high regioselectivity. Stereochem. analyses of the palladium-catalyzed cyclization/carboalkoxylation of both 2- and 3-alkenyl indoles are in agreement with mechanisms involving outer-sphere attack of the indole on a palladium-olefin complex followed by α-migratory insertion of CO and methanolysis of the resulting acyl palladium intermediate. CuCl2 functions as the terminal oxidant in this palladium-catalyzed cyclization/carboalkoxylation of alkenyl indoles and also significantly increases the rate of reaction of 2 with the alkenyl indole to form the corresponding acyl palladium complex. Spectroscopic studies are in agreement with the intermediacy of a heterobimetallic Pd/Cu complex as the active catalyst in this reaction.

Cited 35

Oxidative carbonylation of phenol to diphenyl carbonate catalyzed by ultrafine embedded catalyst Pd-Cu-O/SiO2

By Xue, Wei; Zhang, Jingchang; Wang, Yanji; Zhao, Xinqiang; Zhao, Qian

From Catalysis Communications (2005), 6(6), 431-436. DOI:10.1016/j.catcom.2005.03.013

An ultrafine embedded catalyst Pd-Cu-O/SiO2 was prepd. in a water-in-oil (W/O) microemulsion for the direct synthesis of di-Ph carbonate (DPC) by oxidative carbonylation of phenol with carbon monoxide and oxygen. In this catalyst, there are palladium-copper oxide cores surrounded by the silica shell, which provides protection for the active constituents during the reaction. This can reduce the leaching of the active components and then prolong the catalysts' service time. The embedded catalyst shows higher activity than the catalyst prepd. by sol-gel process and longer service time than the catalyst prepd. by impregnation method. The turnover no. reached about 117.50 (mol-DPC/mol-Pd) at certain conditions. But the leaching of Pd and Cu in the embedded catalyst is still serious for some of them are located on the surface of the silica supports and easily enter into the solvent.

Cited 17

Palladium-catalyzed oxidative carbonylation of 1-alkynes into 2-alkynoates with molecular oxygen as oxidant

By Izawa, Yusuke; Shimizu, Isao; Yamamoto, Akio

From Bulletin of the Chemical Society of Japan (2004), 77(11), 2033-2045. DOI:10.1246/bcsj.77.203

A new preparative method to produce alkyl 2-alkynoates from 1-alkynes in alc. under atm. pressure of CO at room temp. was developed with Pd-phosphine catalysts, using O2 as an oxidant. On the basis of the behavior of model complexes such as methoxycarbonylpalladium and alkynylpalladium complexes, the authors propose a mechanism accounting for the catalytic carbonylation of alkynes through an intermediate having both methoxycarbonyl and alkynyl ligands that liberates Me 2-alkynoates and a Pd(0) species on reductive elimination. The oxidn. of Pd(0) to Pd(II) species in the presence of a halide ion proceeds cleanly with O2 as the oxidant. On the basis of the findings on homogeneous catalysts, a heterogeneous catalytic system using Pd/C also was developed.

Cited 35

Oxidative carbonylation of aniline over a polymer-supported palladium-copper catalyst

By Wan, Boshun; Liao, Shijian; Yu, Daorong

From Reactive & Functional Polymers (2000), 45(1), 55-59. DOI:10.1016/S1381-5148(00)00012-2

The polymer-supported bimetallic catalyst PVP-PdCl2 -2CuCl2 (PVP, poly(N-vinyl-2-pyrrolidone), obtained in situ by the addn. of CuCl2 to an alc. soln. of PVP-PdCl2 , exhibits high selectivity and activity for the oxidative carbonylation of aniline with carbon monoxide and oxygen to Et N-phenylcarbamate in the presence of a base (NaOAc) under atm. pressure. The strong synergic effect of Pd-Cu gives rise to a clear increase in the selectivity and activity.

Cited 8

This is often a sign of catalysis of the reaction by heterogeneous metal particles.

Best would be to synthesize such molecules using diffusion method which involves layering of reagent over the substrate or vice versa through the walls of the tube very slowly and leaving it undisturbed for few hours to days until you get crystalline material which may not dissolve readily but one can generate a very dilution solution of the same in a solvent such as dmso-D6 for NMR recording, if it is not paramagnetic.

We have crystallized hundreds of such highly insoluble molecules using this method and obtained single crystal X-ray data and solved the structures.

as an alternative: use soxhlet extraction method to get a saturated solution or

try to sublime it if it is stable. Many organometallic compounds can also be sublimed to get X-ray quality crystals. We succeeded on several occasions.

No, nanostructures are usually stablized via non covalent interactions like the tertiary structures of proteins. In the end, the product is stabilized by these interactions to give the thernodynamicallymost favoured compound, so the size of the final product is usually the result of the most favoured crystal packing arrangement that optimises these interactions. There are no equations to predict this. If we could control size and the final solid state structures of molecules that would be fanastic.I thnk for certain classes of systems you can predict dominating packing motifs but this is about as far as it goes.

Ethynylferrocene(C5H5FeC5H4 CCH(Mol mass=210) is a monobasic acid. So IM(or1N) will be completely neutralized by IN(or1M) of the monoacid NaOH.

In a way, equal volumes of 10^-6 N of the acid and 10^-6 NaOH on mixing will give neutral solution.

So proceed as follows:

Prepare 0.001N NaOH[ rather than 0.5N NaOH] by dissolving 40/1000=0.04 gm (40mg )/L of NaOH

Now 1L of the acid solution will require just

1.10^-6= X.10^-3

X=0.001L=1 mL of this diluted NaOH for complete neutralization.

So add a few drops of NaOH.

Other than what Philip Jessop said, which I agree with, I'd like to emphasize that there is a big gap about the utility of TON and TOF in academia and industry. While TON can be used for the estimation of the longevity of a catalyst system, TOF says nothing about the real kinetics of a reaction. It can only be used for a very rough comparison of a catalytic activity in the same (or a very similar reaction) under very similar reaction conditions only at low conversions. (TOF depends on the rate order !). It is funny to see TOF values given above 90 or even at 100 % conversion! I would not suggest that the rate order and rate constants should be determined for each and every time, but showing the reaction profile (conversion versus reaction time, 3,4 values) at given reaction conditions (not a lot of work) could give more practical information about the rate and usability of the reaction than a vague TOF.

To couple two aryl halides you may use

---Ullmann reaction; see http://www.organic-chemistry.org/namedreactions/ullmann-reaction.shtm

---Iron-Catalyzed Homocoupling of Aryl Halides and Derivatives in the Presence of Alkyllithiums; see Toummini, Dounia et al, Organic Letters, 15, 4690-4693 (2013)

---Palladium-catalyzed synthesis; see Hajipour, Abdol Reza and Rafiee, Fatemeh, Synthetic Communications, 43, 1314-1327 (2013)

Good luck

In addition to activation with iodine and dibromoethane if you are using turnings is push down on them with a glass stir rod until they break. This gives a fresh oxide free surface.

Dear colleagues, please do not be fooled - magnesium oxide does not react with any of these activators - either with iodine nor with methyl iodide nor with dibromoethane.

Activators react with magnesium in those places where the magnesium oxide film has a small thickness or defective, so the mechanical action improves activation. As a result, these places form cavities filled with a magnesium halide (or Grignard reagent by MeMgI-activation), which leaches by solvent in subsequent steps.

Especially, it can be seen in the preparation of magnesium alcoholates.

In complicated cases, such as the preparation of the Grignard reagent from pentafluoro-chlorobenzene, dibromoethane activation is needed addition in stoichiometric amounts - to refresh magnesium surface because blocking by products of side reactions. Of course, this amount is much larger than the amount of magnesium oxide on the metal surface.

In some cases, such as a Grignard reagent obtaining from CF₃(CF₂CF₂)_nCH₂CH₂-I, presence of homologues with n>= 4 as impurities block reaction completely.

I would recomend you to add a couple of drops of DCM and the n-hexane if your complex or just n-hexane. COD should be soluble there, while the complex not. If you still don't see any precipitate you could put the flask in the fridge for a couple of hours and see if there you can see any solid. Afterwards you just shoud filtrate it off and the COD should be gone.

There are some publications where the authors write that they distilled the COD under reduced pressure but I have never tried it.

Hi, you don't write what you are using the reaction for, and which amine-borane you are using. We used this reaction with dimethylamine-borane ( see: http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201001332/full) in order to reduce organic compounds. As you can see from the SI (attached), even after column chromatography, it was often impossible to get rid of this dimer. If you have very non-volatile other products, you could try to sublime it out. You could also use a different amine-borane of course. If you have long alkyl chains, it will become less polar and maybe come out with the solvent front (on silica chromatography). Hope this helps!

Although I haven't done a Yamamoto myself, and it's with Ni, I can tell you from our experience with Stille cross-couplings, that a Nitrogen adjacent to the Br (in ortho) is a big problem. We have an example for this in J. Linshoeft, A.C.J. Heinrich, S.A.W. Segler, P.J. Gates and A. Staubitz, Org. Lett. 2012 , 14, 5644-5647. See entries 4 and 5. I attach it for you. We speculated that the N complexes the catalyst, but of course, there is no direct proof. However, we see this problem with many N containing aromatic heterocycles: They can be very stubborn in cross-coupling reactions!

> Co(Ph3P)4, if possible then how? If impossible, then why?

It may be possible, I know that Pd(PPh3)4 exist, but again Pdº is larger. Pd(II) reacts very slowly with PPh3 in water to yield Pd(PPh3)4 a Pdº species.

Co(PPh3)4 is a 17 electron species, so I strongly recomend you to reduce this complex.

Which solvent used to crystallization... My idea is whatever the solvent you can take small amount of solute than the solvent that is main thing..

alpha-Fe2O3 is the classical catalyst for high-temperature water gas shift reaction. At reaction conditions it is converted to magnetite (Fe3O4), which is the active state of the catayst. Treat hematite at above 350 C in typical WGS reaction medium (NOT in H2, it should be either H2+CO2+H2O in proportion of ca. 45:15:40 or H2+CO2 in proportion of smth like 1:2). This will give you magnetite. Simple treatment in hydrogen would give you a number of iron oxides.

In some cases the direct reaction between SiCl4 and RNH2 work to give the desiree product Si(NHR)4 but the reaction is limited by sterically-demandindg amines

See

Metal and metalloid amides. Syntheses, structure, and physical and chemical properties

Lappert et al.

Ellis Horwood Publisher 1980

Add a few drops of 1,4-dioxane. It shifts the schlenk equilibrium to give Bn2Mg and MgCl2 which are very insoluble and then after removing all solvents under reduced pressure, your product can be extracted with aromatic or hydrocarbon solvent, depending on solubility.

You can titrate the Grignard reagent following the procedure of Watson and Eastham in J. Organomet. Chem. 1967, 9, 165. A grignard forms a violet complex with 1,10-phenanthroline, and you can titrate it using an alcohol. Originally they used sec-butanol, but menthol is more convenient to use at it is a water-free solid and readily available. This method is quite accurate, since it will not give higher results due to basic hydrolysis products (e. g. magnesium alkoxides or hydroxides).