Dears
I have a cluster of the general formula :
[(P4W6O34)2Co2Na2(H2O)2]18- and I found only (Na10(H2O)18)10+
The rest 8+ of charge may be attributed to undetermined sodium disorder cations or (H3O)+ . From single crystal X-ray, it is obvious that there is no more than water and my question is how to show that there is (H3O)+ or not and in case of si, how to determine there exact location and whether they are inside the cluster or free protonated waters inside the lattice.
As shown in the formula, it contains cobalt which is a headache and so it is difficult to be analyzed by H-NMR . In addition, the TGA shows two types of water with 27H2O which is agree with the crystal solution.
N.P.
Attached The 31P-NMR of the title compound.
This is a question from the refree: The charge of the polyanion (-18) as shown in the title and throughout the manuscript is wrong. If the six phosphate groups are indeed protonated, as claimed, it should be rather -12 (see also the final formula of the hydrated salt). At the same time, protonation of the oxygens of these groups is not supported by results of bond valence sum calculations shown in Table 3. Therefore the missing protons could easily be present within hydronium counterions. This issue should be further elaborated and discussed.
Sincerely, Yours
Dear,
yes I know it very well and I know that we have the same core. However, there formula is (H2bhep)2Na10[P8W12Co2Na2(H2O)2O68{Co2(H2O)4}]·8H2O. We have tried to obtain a crystal without the external cobalt or the organic part. So, the obtained crystal as mentioned [(P4W6O34)2Co2Na2(H2O)2]18- and I found only (Na10(H2O)18)10+. now the problem is to justify the extra H3O+ to compensate the charge of the polyanion. The objective of obtaining these polyanions as well as others is to have an idea about the relationship between the WOC activitity vs. lattice systems in absence of carbons.
May be a good suggestion, Do you have an experimental to have good results with ionic system like POMs and acceptable.
The acid-base titration of POMs is a routine technique in our laboratory. I use CurTiPot software to interpret the data
http://www.iq.usp.br/gutz/Curtipot_.html
Really many thanks Geletii. I checked one of your article "http://www.rsc.org/suppdata/cc/b9/b926064a/b926064a.pdf" and the nice software your supplied me CurTiPot. I will follow them.
Dear, can you help me in knowing what is the meaning of the chemical shift at -2.08, 2.1 and 137.146?
Dear , I have done a titration with HCl and I get the following. it means that I have (OH) or not? and in case of yes, where they are located?, BVS shows nothing of hydroxides
The most likely that the aqua ligand(s) of Co are deprotonated in solid state. You may have something like "[P8W12Co2Na2(H2O)2O68{Co2(H2O)2(OH)2}] in crystal. I would try to explain why the natural pH of the POM solution is close to neutral. Try to Use CurtiPot to simulate your titration curve assuming different protonation states of your POM in solid state. By the way, at what pH you have grown crystals?
The reaction was ajusted to pH 6.5
Th BVS is equal to 2 for all waters in the crystal
To interpret your titration curve you must know the exact amount of acid or base added for pH adjustment. CurTiPot allows to take into account such adjustments.
What were the natural pH before adjustment and POM concentration? Plz, reply promptly. I'm falling asleep.
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