For my organometallic complex of the type [RuCl2(Z)], where Z is a neutrally coordinated ligand, I am observing distinct changes in UV Visible spectrum upon hydrolysis (complex is added to water). However my time dependent NMR and mass spectrum of the same complex shows that the original complex remains intact. Is it possible? Why do we observe changes in UV-Vis spectrum then?
What about FT-IR and Raman spectroscopy? is there any changes in them? You need to find what is happening during hydrolysis. any bond breaking and formation occurring? if yes, the absorption will change.
No we have maintained same solvent mediums in all the repeated test done.
Dear Srividya Swaminathan many thanks for your interesting technical question. In my opinion the most plausible explanation is that in the course of the hydrolysis one of that chloride ligands in your original ruthenium(II) complex is replaced by water so that you get a cationic aqua complex of the type [RuCl(H2O)(Z)]+Cl–. This could have a somewhat different UV-Vis spectrum, whereas the NMR would not change as you see only the organic ligand anyway. The question to me is if the NMR spectrum has also been run in the presence of water? The mass spectrum certainly does not reflect the coordination of the complex in solution. It would be interesting to grow crystals from the hydrolysis reaction mixture e.g. for X-ray diffraction or an elemental analysis.
For some potentially useful references please have a look at the following articles. In one of them the formation of a ruthenium quo complex from a chloroformed precursor is described:
A Ruthenium(II) Aqua Complex as Efficient Chemical and Photochemical Catalyst for Alkene and Alcohol Oxidation
https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/ejic.201801206?af=R
and
Experimental and computational studies on ruthenium(ii) bis-diimine complexes of N,N'-chelate ligands: the origin of changes in absorption spectra upon oxidation and reduction
Article Experimental and Computational Studies on Ruthenium(II) Bis-...
Frank T. Edelmann Thank you for your suggestion sir. Yes, NMR was recorded in water, and there is no observable shifts in any of the peaks. I will try to crystallize the hydrolysis product.
You may try gradually adding small amounts of water to a solution of your complex (1 or 2 molecules per complex molecule) . This can give you a clue about the nature of the forming species. May be, you will be able to observe a signal of coordinated water in the NMR spectrum.
Dear Srividya Swaminathan thank you again for your interesting question. If you would provide a few more details what you additional ligand Z is, I could do a SciFinder search and look for the reactivity and hydrolysis of the particular ruthenium complex. Is you starting ruthenium(II) complex a known or a new compound? It would also be interesting to know why you are carrying out this hydrolysis study. If you want to isolate the hydrolysis product, which is presumably a cationic species, you could try to isolated it by precipitation with a large anion such as tetraphenylborate,
https://www.britannica.com/science/chemical-compound/Spectroscopy-of-organic-compounds]
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