HW 2 Multinuclear NMR Name:
Points: C6800 Date:
Max. 100 points Spring 2017 Version A
1. (2 pts) The 119
Sn NMR resonance of the Sn atom at the apex of the square pyramid in 3 was
found to be extraordinarily shielded, being observed at −2441.5 ppm. The value closely
approaches those of the stannocene derivatives, with their record high-field tin resonances
appearing in the range from −2100 to −2300 ppm. Explain these observations considering the
two resonance structures of pyramidane 3, covalent and ionic. Which one is more important?
2. (38 pts) Draw all possible complexes [PFx(CN)6-x] (x = 0 – 6) and predict multiplicities of
signals in 31
P and 19
F NMR spectra (number of resonances, name of a multiplet, and the
relative intensities of lines in a multiplet).
x Molecule 31
P 19
F
6
5
4
and so on….
3. (44 pts) Find the symmetry point groups of the following molecules.
How many signals do you expect in the 1
H and 29
Si NMR spectra.
Mark all geminal groups in these molecules as homotopic (H), enantiotopic (E) and
diastereotopic (D).
4. (4 pts) Explain the 19
F {1
H} NMR spectrum the following molecule.
5. (12 pts) Calculate relative populations of Te isotopologues of this cation. (Disregard the Se
isotopes, use  = 2, for the two-fold axis that interchanges the Te atoms)