Hi Simone,

I am starting to work with Pd(neocuproine) complexes. Mainly for organometallic synthesis. I can recommend you the recent paper of Waymouth (http://onlinelibrary.wiley.com/doi/10.1002/ange.201400134/abstract). What is the reaction you want to perform?

Cheers,

Yann

Ok. Basically now I am looking for to activate the PdNc(OAc)2 wirh triflic acid in ACN solution.This step in order to obtain the dimer form of the complex to use as homogeneous catalyst. Anyway the NMR analysis not confirm the complete activation of the complex, but maybe I know way: the TfOH in ACN produces a series of co-products but only one is necessary (reference: Interaction with acetonirile with TfOH: unexpected formation of wide structures; George E. Salnikov) in my opinion. In this period I am conducting a series of experiments to try to understand the activation time for the ACN doing NMR analysis every 24 h.

On the other hand as catalyst the PdNc(OAc)2 has the de-activation problems.

Thank you for your suggestion.

p.s. I am studyng the selective oxydation of the glycerol to DHA with heterogeneous and homogeneous catalysts. (the link does not work, can you tell me the year of publication?)

Sure: angewandte(acie) 2014, 126, 5754-5758.

Good luck

Dear Simone,

indeed the TfOH ACN solution has to  be made fresh and used immediately. When it did turn yellow do not use it it won't work.

Greetings

Manuel, it is strange for me what are you saying!

I made an NMR analysis and I obtained the signal related to the organometallic specie only after I have waited for 72 hours...when the solution is become yellow. I don't want put in to question what you say, but it is important for me to understand. Have you ever tested your catalyst to better undestand the compound stability?

thx

Simone,

maybe I still do not understand what the problem is. You want to make Pd(Neocup)(ACN)2(TfOH)2 right? As has been described by R. Waymouth (http://pubs.acs.org/doi/abs/10.1021/om700492n). For me that work very well following that procedure.And for that you have to briefly stir Pd(Neocup)(OAc)2 in a TfOH solution in ACN and than precipitate it with ether (for me after addition of the TfOH solution in ACN it went from suspension to solution and  precipitated immidiatly again ). What I meant is that you can not store the solution of TfOH and ACN, so you have to make that fresh.

Any stability test I did not perform.

Greetings

I followed the procedure proposed by Waymouth. The problem is: I took the precipitate, I did an H-NMR and C-NMR analysis but the structure proposed is not the theoretical one. We obtain the proposed structure only after using the TfOH:ACN solution (1:60 ad molar ratio) at 72 hours. The idea to wait until 72 hours come from the following work: "INteraction of acetonitrile with trifluoromethanesulfonic acid: unexpected formation of a wide variety of strcutures_ Salnikov, Genaev et al." Do you use the same molar ratio I use?

p.s. When I asked if you did stability test I referred to the formation of mirror Palladium during the reaction.

Best regards

Dear Simone,

for me all the NMR spectra were ok. I even could do the next step to make the dimer, which was also active in the selective oxidation of glycerol and in the oxidation of glycosides ([1] M. Jäger, M. Hartmann, J. G. de Vries, A. J. Minnaard, Angew. Chem. Int. Ed. Engl. 2013, 52, 7809–7812.).

One thing I always did was to work dry (even though I think it is not specifically mentioned by waymouth) so Schlenk techniques, drying of the complexes in high vacuum over night and dry ACN.

The other thing I do not under stand is that you want to wait 72h, I know that paper about the TfOH/ACN and there you see that over time you have a lot of side products. This would make it even much more difficult to separate. Another thing is the Pd mirror you get over time (that I saw basically on my NMR samples when I did store them for a long time. Bottom line is I don't think it is a good idea to keep it so long as solution. And maybe what you see after 72h is not the complex after all.

My advise is make sure that you do the reaction probably (if you did not so far) and (that can be overlooked) is to use deutero ACN for the NMR (with DMSO I had problems, I think you get exchange of ACN for DMSO as ligand).

I hope that helps.

Good luck

Manuel

Sorry again. I observed the mirror palladium only when the catalyst reacts with diols.

I do not use the dry ACN...maybe it is the problem!

I know that waiting a lot of side products appear, but I wait in order to abtain the activate ACN.

I'am going to do some evaluation and experiments, thanks a lot for your time.

Simone