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Pt-195 NMR spectra for different geometries of [Pt(Cl)(Br)(PPh3)2]

Question asked by Monica VAN DER WALT on May 27, 2020

The question off which I am basing my question assumes that [Pt(Cl)(Br)(PPh3)2] can exist in either the square-planar or tetrahedral geometry. If one would use Pt-195 NMR spectroscopy how would the spectra of the possible molecules differ from each other? The effect of the Cl and Br can be disregarded.

 

My reasoning:

For the square planar geometry, either the cis or trans isomer is possible. I am assuming that you won't be able to distinguish between the square planar trans molecule and the tetrahedral molecule since the PPh3 ligands in each molecule are equivalent. The Pt-195 NMR spectra for these two orientations will thus be the same, a single triplet. 

 

Will the square planar cis molecule also produce the same spectrum or will there be second-order coupling present since the PPh3 ligands are non-equivalent? How would the Pt-195 NMR spectra then look for the cis isomer? Thank you in advance for anyone willing to help!

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