i have prepared cobalt metal complex using methanol as a solvent. one of the position was occupied by Methanol(as neutral ligand. i have conformed the structure by NMR,ESI-MS,CHN)
since the complex insoluble in water i have studied the DNA binding study by dissolving the complex in DMSO.
My doubt is, in the solution,whether the methanol is replaced by DMSO. if yes, how can i characterize ?
kindly help me. if it possible let me know the related article.
Donor number is 29 for DMSO and around 19 for Methanol, So presumably, MeOH is replaced by, DMSO. The problem is the existence of coordination isomer. S coordinate or O coordinate. MS cannot tel the difference. NMR also difficult to detect. measurement of IR for S=O stretching mode helps the detection of the isomerism.
If you can prove by using NMR that MeOH is coordinated in your complex you can also see when it is not. Joining the opinion of Prof. Kinoshita, I also think that DMSO can (and should) replace MeOH in your complex in DMSO solution not only because it is a better ligand but also because it is in an enormous excess compared to MeOH. IR could only be useful in answer to your question if you had an isolated DMSO complex, not a solution of it in DMSO.
This question is an important one. In the most part, complexes that do not dissolve in water do dissolve in DMSO. The simple reason is that DMSO is a highly coordinating solvent. In your case, it can actually displace methanol. NMR has a specific chemical shift for DMSO, but it will be difficult to say with accuracy if it is the coordinated DMSO or free solvent DMSO since the NMR is run in DMSO. It would be preferable to detect DMSO by IR. If you are lucky to have the compound crystallize in DMSO, the X-ray crystal structure would solve the problem. There is however, a lot to play around with to be able to conclude with certainty.
Yes, DMSO can replace MeOH. I have Ni(II) complex with a coordinated neutral MeOH. On recrystalliztion from DMSO, MeOH is replaced by DMSO. Both structures are confirmed by single crystal X-ray diffraction analyses.
I am also joining Profs. Kinoshita's and Tóth's opinion about DMSO replacing MeOH in a complex.You may want to check out Characterization of DMSO Coordination to Palladium(II) in Solution and Insights into the Aerobic Oxidation Catalyst, Pd(DMSO)2(TFA)2 by Tianning Diao, et al., Inorg. Chem. 2012 Nov. 5; 51(21):11898-11909, available on the Internet. Table1 gives IR and 1H NMR Spectroscopic Data of DMSO and Transition Metal-coordinated DMSO Reported in the Literature for both S-DMSO and O-DMSO ligands. www.ncbi.nlm.nih.gov/pmc/articles/PMC3494491/table/T1/
also references to comprehensive reviews (ref.#10)
Best wishes1
- Badges
- Science topic