Is it possible for a metal complex to change its coordination mode between solid and solution state?? My crystal data indicates bidentate coordination whereas NMR inidicates monodentate one.
https://www.york.ac.uk/media/chemistry/research/douthwaite/Metal-Ligand%20bonding%20and%20Inorganic%20reaction%2
https://www.sciencedirect.com/topics/chemistry/charge-transfer-complex
https://opentextbc.ca/chemistry/chapter/19-2-coordination-chemistry-of-transition-metals/
This may be useful to you
Yes. It is possible and depends on the type of ligand you are using. ambidentate ligands such as dppm (1,2-bis(diphenylphosphino)methane or in general short bite ligands due to the ring strain or any other reason arising in solution medium (some time in solid state also but rarely on mechanical grinding or on exposure to uv light) can change their coordination mode and hapticity as well. Anionic ligands such as acetates or acacs can show chelating, bridged bidentate and monodentate coordination. In solution, especially in a donor solvent, due to some reason, a bidentate ligand can turn into a monodentate to limit its coordination number or to overcome ring strain and offer the vacant site to another monodentate ligand. Since you did not reveal which metal ion and which ligand(s) you are using including what solution, the suggestions are limited.
Good luck with your work
Balakrishna
I agree with the opinions mentioned above. Yes, it is possible to change the coordination mode of a metal complex from solid state to solution. The solvent can play an important role, especially if it can act as a ligand coordinating to the metal ion. An interesting example is the activation of the inactive form of [Co (salen)] through the formation of an adduct with DMSO (dimethylsulfoxide) and the reversible complexation of dioxygen. When the inactive [Co (salen)] (red) dissolves in donor solvents ( DMSO, DMF, Py….) in the presence of dioxygen, it rapidly forms adducts.
Dear Srividya Swaminathan many thanks for your interesting technical question. This is in fact quite common. Especially when your use a coordinating solvent such as THF, DMSO, or water you can have an equilibrium between bidentate (chelating) and monodentate coordination modes of certain ligands. there are many examples in the literature where metal complexes have different structures in the solid state and in solution.
Pease have a look e.g. at the following relevant references:
1. Relationship between solid state structure and solution stability of copper(II)–hydroxypyridinecarboxylate complexes
https://pubs.rsc.org/en/content/articlehtml/2019/nj/c9nj01469a
2. Solid-State and Solution-State Coordination Chemistry of Lanthanide(III) Complexes with (Pyrazol-1-yl)acetic Acid
Article Solid-State and Solution-State Coordination Chemistry of Lan...
3. Solid-State and Solution-State Coordination Chemistry of the Zinc Triad with the Mixed N,S Donor Ligand Bis(2-methylpyridyl) Sulfide
Article Solid-State and Solution-State Coordination Chemistry of the...
These are just a few typical examples.
Dear all, yes it is possible and very common. Coordination of complexes is usually interpreted by Lewis acid-base interactions, i.e., which arrengements are more likely to lead to high stability. My Regards
Dear Srividya Swaminathan ,
if you search for "hemilabile ligands", you will probably find much more examples, in addition to the ones given before. Some own experience:
Helvetica Chimica Acta vol. 82 (1999), 811-820
Yes it is possible, depending upon different solvents you use. Some strong coordinating solvents infact can replace some ligand systems as well.
Dear Srividya
Yes, it is possible. It also depends on the metal ion (whether 3d, 4d or 5d), its oxidation state and also the nature of the ligands. One has to look into: i) Labile complexes verses stable complexes, ii) nature of the ligands. Hard acid-base pair and soft acid -base pair are more stable, whereas other combination can make the complexes labile. Also, chelating ligands with different donor atoms can dissociate one of the M-L bonds to form dimers, if it is four-membered chelate ring. Usually five- and six-membered chelate rings are more stable as they are strain free. Four-membered ring involving ligands such as dppm are more vulnerable for dissociation even in a soft-soft combination. It all depends on, as I had mentioned in the beginning, nature of that particular metal complex and also the solvent you are using. In non-donor solvents such changes are restricted unless there is an excess of ligand present in the solution.
Balakrishna
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