HW 2 Multinuclear NMR Name:
Points: C6800 Date:
Max. 100 points Spring 2015 Version A
1. (25 pts) Predict the number and relative intensities of the signals in the 29
Si NMR spectra of
molecules 1–3. Mark chemically different Si atoms with different colors. Give the symmetry
point groups (Si-O-Si is linear in 3, consider both conformations).
2. (20 pts) The tin fluoride complex 4 was synthesized by the following procedure:
a) Draw clearly all symmetry elements present in the complex 4.
b) Give the symmetry point group of the complex 4.
c) Are there any geminal groups? Assign them as Homo-, Enantio-, or Diastereotopic.
d) How many resonances (signals) do you expect in the 1
H, 13
C, 119
Sn, and 19
F NMR spectra.
Molec. Signal intensities P.G.
1
2
3
staggered
3
eclipsed
3. (18 pts) Consider the following compounds:
a) Are there any geminal groups in these molecules? Assign them as Homo-, Enantio-, or
Diastereotopic.
b) How many signals do you expect in the 1
H NMR spectrum in the Si-H region?
Me3P
Pt
SiH2Ph
C SiH2Ph
N
tBu
Me3P
Pt
SiH2Ph
C SiH2Ph
N
4. (31 pts) Consider the following complexes (also R/S diastereomers):
a) Are there any geminal groups in these molecules? Assign them as Homo-, Enantio-, or
Diastereotopic.
b) How many CH3 signals do you expect in the 1
H NMR spectrum?
c) Give the symmetry point group of the complexes (consider R/S diastereomers).
5. (6 pts) How many signals do you expect in 19
F a 31
P NMR
spectra of the following compound:
O
P
O
F
F
Cl P
F
N
F
Cl