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Return to NMR Spectroscopy in Inorganic Chemistry 2e Student resources
Chapter 2 Multiple Choice Questions
Structure determination
Quiz Content
*
not completed
.
Which statement is
incorrect
?
The chemical shift results in a separate multiplet of resonances for each chemically different group of NMR active nuclei.
correct
incorrect
The structure within each multiplet results from scalar coupling and is symmetrical about the midpoint of the multiplet, in the absence of 2
nd
-order effects.
correct
incorrect
Integration of each resonance in the spectrum gives the absolute number of nuclei responsible for each chemical shift.
correct
incorrect
To distinguish scalar couplings from chemical shifts one should look for the symmetry present in a scalar coupled multiplet.
correct
incorrect
*
not completed
.
Consider the following compound, P(OEt)
3
:
How many chemical shifts and what kind of coupling constants will be observed in the
1
H NMR spectrum? (You may ignore couplings over more than three bonds.)
Two chemical shifts: a triplet (
3
J
HH
) due to the Me group which couples to the directly bonded CH
2
and a doublet (
3
J
PH
) of quartets (
3
J
HH
) due to the CH
2
group which couples to the phosphorus and to the attached Me group.
correct
incorrect
Two chemical shifts: a triplet (
3
J
HH
) due to the Me group which couples to the directly bonded CH
2
, and a quartet (
3
J
HH
) due to the CH
2
group which couples to the attached Me group.
correct
incorrect
Two chemical shifts: a triplet (
3
J
HH
) due to the Me group which couples to the directly bonded CH
2
, and a triplet (
3
J
HH
) due to the CH
2
group which couples to the attached Me group.
correct
incorrect
Two chemical shifts: a triplet (
3
J
HH
) due to the Me group which couples to the directly bonded CH
2
and a doublet (
3
J
PH
) of triplets (
3
J
HH
) due to the CH
2
group which couples to the phosphorus and to the attached Me group.
correct
incorrect
*
not completed
.
Consider the following compound:
How many chemical shifts and what kind of coupling constants will be observed in the
1
H NMR spectrum? (You may ignore couplings over more than three bonds.)
Three chemical shifts: a doublet (
1
J
PH
) for H directly bonded to P; a doublet (
3
J
PH
) of septets (
3
J
HH
) for the methyne proton coupling to P and the directly bonded methyl groups; and a doublet (
3
J
HH
) due to the CH
3
group coupling to the methyne proton.
correct
incorrect
Four chemical shifts: a doublet (
1
J
PH
) for H attached to P; a doublet (
3
J
PH
) of septets (
3
J
HH
) for the methyne proton coupling to P and to the directly bonded methyl groups; and
two doublets (
3
J
HH
) due to the methyl protons of the two pairs of CH
3
groups coupling with the methyne.
correct
incorrect
Five chemical shifts: a doublet (
1
J
PH
) for H attached to P; a doublet (
3
J
PH
) of septets (
3
J
HH
) for the methyne proton coupling to P and to the directly bonded methyl groups; and
four doublets (
3
J
HH
) due to the four CH
3
groups coupling to the methyne protons.
correct
incorrect
Three chemical shifts: a doublet (
1
J
PH
) for H attached to P; a septet (
3
J
HH
) for the methyne proton coupling to the directly bonded methyl groups; and a doublet (
3
J
HH
) for CH
3
group coupling to the methyne proton.
correct
incorrect
*
not completed
.
Consider the following compound, Et
2
PCH
2
P(O)Et
2
:
How many chemical shifts and what kind of coupling constants will be observed in the
31
P NMR spectrum? (You may ignore couplings over more than three bonds.)
One chemical shift: a septet (
2
J
PH
) due to the phosphorus atoms which couple equally to each of to the three CH
2
groups.
correct
incorrect
Two chemical shifts: each will be a doublet (
2
J
PP
) of triplets (
2
J
PH
) of quintets (
2
J
PH
) due to coupling of the inequivalent phosphorus centres to each other, to the central CH
2
group, and to the CH
2
groups of the two directly bonded Et residues. Coupling constants to the different types of CH
2
groups will be different.
correct
incorrect
Two chemical shifts: both are triplets (
2
J
PH
) of quintets (
2
J
PH
) due to coupling of phosphorus to the central CH
2
group and to the CH
2
groups of the two directly bonded Et residues. Coupling constants to the different types of CH
2
groups will be different.
correct
incorrect
Two chemical shifts: both are octets due to coupling of the phosphorus centres to each other (
2
J
PP
) and to the three directly bonded CH
2
groups (
2
J
PH
).
correct
incorrect
*
not completed
.
Consider the following compound:
How many chemical shifts and what kind of coupling constants will be observed in the
31
P NMR spectrum?
Two chemical shifts: both are doublets (
2
J
PP
) of doublets (
2
J
PH
) due to coupling to the other phosphorus and to the methylene hydrogens.
correct
incorrect
Two chemical shifts: both are doublets due to coupling of the inequivalent phosphorus centres to each other (
2
J
PP
).
correct
incorrect
One chemical shift: a triplet (
2
J
PH
) due to coupling of the equivalent phosphorus centres to the methylene hydrogens.
correct
incorrect
Two chemical shifts: both are doublets (
2
J
PP
) of triplets (
2
J
PH
) due to coupling of the inequivalent phosphorus centres to each other and to the methylene hydrogens.
correct
incorrect
*
not completed
.
Consider the following compound:
How many chemical shifts and what kind of coupling constants will be observed in the
19
F NMR spectrum? (You may ignore couplings over more than three bonds.)
One chemical shift: a doublet of septets due to coupling to phosphorus with
2
J
PF
, and coupling to the six fluorines in the CF
3
groups with the
3
J
PF
.
correct
incorrect
Two chemical shifts: a sextet (
3
J
FF
) due to coupling of the unique fluorine to the six fluorines in the CF
3
groups and a doublet (
3
J
FF
) due to coupling of the CF
3
groups to the unique fluorine.
correct
incorrect
Two chemical shifts: a doublet (
2
J
PF
) of septets (
3
J
FF
) due to coupling of the unique fluorine to phosphorus and to the six fluorines in the CF
3
groups; and a doublet (
3
J
PF
) of doublets (
3
J
FF
) due to coupling of the CF
3
groups to phosphorus and to the unique fluorine.
correct
incorrect
Three chemical shifts: a doublet (
2
J
PF
) of quartets of quartets (
3
J
FF
) due to coupling of the unique fluorine to phosphorus and to the three fluorines in each CF
3
group and two doublets (
3
J
PF
) of doublets (
3
J
FF
) due to coupling of the CF
3
groups to phosphorus and to the unique fluorine. Coupling between the CF
3
groups is not observed since >
3
J
.
correct
incorrect
*
not completed
.
Consider the
129
Xe NMR spectra of XeF
2
and XeF
4
. Which statement is
correct
?
The
129
Xe NMR spectrum of XeF
4
shows a quintet due to coupling of Xe to F (
1
J
XeF
) and is more shielded than the resonance of XeF
2
. For XeF
2
, one chemical shift is observed, a triplet due to coupling of Xe to F (
1
J
XeF
).
correct
incorrect
The
129
Xe NMR spectrum of XeF
4
shows a quintet due to coupling of Xe to F (
1
J
XeF
) and is deshielded compared to the resonance of XeF
2
. For XeF
2
, one chemical shift is observed, a triplet due to coupling of Xe to F (
1
J
XeF
).
correct
incorrect
The
129
Xe NMR resonances of both compounds occur at similar chemical shifts. The spectrum of XeF
4
shows a quintet due to coupling of Xe to F (
1
J
XeF
) and the resonance of XeF
2
is a triplet due to coupling of Xe to F (
1
J
XeF
).
correct
incorrect
The
129
Xe resonance of XeF
4
is more deshielded than that of XeF
2
. Both are singlets.
correct
incorrect
*
not completed
.
Consider the following compound:
How many chemical shifts and what coupling will be observed in the
77
Se
NMR spectrum? (Ignore long-range couplings over more than three bonds.)
One chemical shift: a doublet (
2
J
SeP
) of quartets (
3
J
SeH
) due to coupling of selenium to phosphorus and the Me group.
correct
incorrect
One chemical shift: a doublet (
2
J
SeP
) due to coupling of selenium to phosphorus.
correct
incorrect
One chemical shift: a doublet (
2
J
SeP
) of triplets (
3
J
SeH
) due to coupling of selenium to phosphorus and the Me group.
correct
incorrect
One chemical shift: a singlet, there is only one type of
77
Se in the molecule.
correct
incorrect
*
not completed
.
Consider the
195
Pt NMR spectrum of PtF
6
. Which statement is
correct
?
The
195
Pt resonance of PtF
6
is a singlet.
correct
incorrect
The
195
Pt resonance of PtF
6
is a septet due to coupling to a group of six equivalent fluorines.
correct
incorrect
The
195
Pt resonance of PtF
6
consists of a central singlet with satellites due to coupling to six fluorines.
correct
incorrect
The
195
Pt resonance of PtF
6
is a quintet of triplets, due to coupling to the group of four equatorial fluorines and the group of two apical fluorines. The coupling constants to the apical and equatorial fluorines are different.
correct
incorrect
*
not completed
.
Consider the proton and carbon coupled
29
Si NMR spectrum of MeSiCl
3
in CDCl
3
. Which statement is
correct
?
The
29
Si NMR spectrum shows one chemical shift, a doublet (
1
J
SiC
) of quartets (
2
J
SiH
) due to coupling of Si with
13
C and H.
correct
incorrect
The
29
Si NMR spectrum shows one chemical shift, a quartet (
2
J
SiH
) due to coupling of Si with H with satellites due to coupling to
13
C (
1
J
SiC
).
correct
incorrect
The
29
Si NMR spectrum shows one chemical shift, a singlet with satellites due to coupling to
13
C (
1
J
SiC
).
correct
incorrect
The
29
Si NMR spectrum shows one chemical shift, a quartet due to coupling of Si with H (
2
J
SiH
).
correct
incorrect
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