2-NMR-H

NMRNMR NNuclear M Magnetic RResonance

ProtonProton NMRNMR

Index NMR-basicsNMR-basics

Anisotropy of Aromatic compounds: in plane and aboveAnisotropy of Aromatic compounds: in plane and above

CH3

CH3

H

H

H

H

H

H

H

H

H

H

ringring 8.14-8.64 ppm 8.14-8.64 ppm

MeMe -4.25 ppm -4.25 ppm

H H

ringring 7.27-6.95 ppm 7.27-6.95 ppm

MeMe -0.51 ppm -0.51 ppm

OUTSIDEOUTSIDE 9.28 ppm 9.28 ppm

INSIDEINSIDE -2.99 ppm -2.99 ppm

HH

HH

H

H

H

H H

H

H

H

H

HH

H

H

H

Anisotropy: AromaticAnisotropy: Aromatic

Electronic effectsElectronic effectsCH2

O

CH3

CH2+

O-

CH3

DeshieldedDeshielded

O

O

O

H

H

7.10 ppm7.10 ppm

COOEt

COOEt

H

H

COOEt

H

H

EtOOC

6.83 ppm6.83 ppm6.28 ppm6.28 ppm

O

H

H7.71 ppm7.71 ppm

6.10 ppm6.10 ppm

O

H

H

H

H7.07 ppm7.07 ppm 6.38 ppm6.38 ppm

6.28 ppm6.28 ppm

5.93 ppm5.93 ppm

8 7 6 5 4 3

O12

3

4

5

6

O7

Electronic effects: conjugation with carbonylElectronic effects: conjugation with carbonyl

8 7 6 5 4 3 2

O1

2

34

56

7.75

6.20


deshieldeddeshielded

Electronic effects: conjugation with heteroatomElectronic effects: conjugation with heteroatom

OH

H

O+

C-

H

H

SH

H

6.06 ppm6.06 ppm

5.48 ppm5.48 ppm

S

H H

5.81 ppm5.81 ppmO

H H5.78 ppm5.78 ppm

OH

H4.82 ppm4.82 ppm

6.22 ppm6.22 ppm

shieldedshielded

6.5 6.0 5.5 5.0 4.5 4.0 3.5

12

34

O5

Electronic effects: no conjugation with heteroatomElectronic effects: no conjugation with heteroatom

7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5

12

34

O5

2.65 2.60 2.55

6.35 6.30 4.95 4.90

shieldedshielded


O CH3

8 7 6 5 4 3 2

8.0 7.5




oo

pp

mm

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5

OCH3

7.3 7.2 7.1 7.0 6.9 6.8


ShieldedShielded

shieldedshielded

oopp

mm

NHCH3

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5

7.0 6.5


ShieldedShielded

shieldedshielded

oopp

mm

F

7.5 7.4 7.3 7.2 7.1 7.0 6.9

Cl

7.4 7.3 7.2 7.1

Br

7.6 7.5 7.4 7.3 7.2 7.1

Aromatic: inductive effect and resonance effectAromatic: inductive effect and resonance effect

Hydrogen bondHydrogen bond

Protons on HeteroatomsProtons on Heteroatoms

• OHOH, NHNH, SHSH– Exchangeable (with D2O)

– Hydrogen bonding– On NitrogenNitrogen (1414NN), as the spin state of that

nuclei is 11, there can be partial coupling that produce broaden lines. There can be also full coupling that would produce 3 lines of equal 3 lines of equal intensityintensity (I=1I=1 has 3 orientations3 orientations in a magnetic field)

Protons on HeteroatomsProtons on Heteroatoms• OHOH

– AliphaticAliphatic 0.5-4.0 ppm 0.5-4.0 ppm (depend on Concentration)– Intramolecular hydrogen bondingIntramolecular hydrogen bonding deshield OHOH and render it

less sensitive to concentrationless sensitive to concentration• Usually Usually OHOH exchange rapidly (no coupling with (no coupling with

neighborsneighbors• In In DMSODMSO or or AcetoneAcetone, the exchange rate is slower => , the exchange rate is slower =>

there is there is coupling with neighborscoupling with neighbors

• PhenolsPhenols : : 7.5-4.0 ppm 7.5-4.0 ppmIntramolecular bond 12-10 ppm

• Carboxylic AcidsCarboxylic Acids: : Exist as Dimers 13.2-10 ppm

HH22OO signal moves with signal moves with temperaturetemperature

HH22OO

OHOH in DMSO in DMSO

CHCH33--CHCH22--OHOH

OHOH CHCH22

qdqd

(CH(CH33))2 2 --CHCH--OHOH

OHOHCHCH

Protons on HeteroatomsProtons on Heteroatoms

• NH : NH : 1414N: I=1N: I=1 => 2I+1 lines=> 2I+1 lines• NHNH has different rate of exchange• 14N can relax quickly. Depending on relaxation rate,

heteronuclear coupling will be visible or produce broadened peaks.

• R-NHR-NH : Aliphatic amines => rapid exchange– Sharp singlets : no coupling to N: N: ~3-0.5 ppm~3-0.5 ppm

• R-NHR-NH: Amides, Pyrroles, Indoles, Carbamates– NHNH broad– CHCH shows coupling the NHNH

AmideAmide

Protonated AminesProtonated Amines

FormamideFormamide

HH-CO-N-CO-NHH22

H-NMR

H{14N}-NMR

NHNH: Amide, Pyrrole Indole: 8.5-5.0 ppm: 8.5-5.0 ppm

In AmidesAmides: Slow rotationSlow rotation can show different isomers

H NH

CH3

O

H NCH3

H

O

In Amine Salt:In Amine Salt:

• Moderate Rate of exchange => broad peaks ~ 8.5-6.0 ppm•CH => show coupling to NH+

Sometimes broad [NH[NHxx++]] consist of 3 broad hump3 broad hump due to 1414N couplingN coupling

11JJNHNH ~ 50 Hz ~ 50 Hz

SHSH• Slow exchangeSlow exchange

SHSH couple to CHCH

• When shaken with D2O, SH DisapearSH Disapear

~ 1.6 – 1.2 ppm Aliphatic SH ~ 1.6 – 1.2 ppm Aliphatic SH ~ 3.6 – 2.8 ppm Aromatic SH ~ 3.6 – 2.8 ppm Aromatic SH

Chemical Shift and Chemical Shift and CouplingCoupling

An example: An example: CC1010HH1212OO22 II = = 1010 + 1 – + 1 – 1212/2 = /2 = 55

Me-C=CMe-C=C

X 4 = 12X 4 = 12

J=8 HzJ=8 HzJ=7 HzJ=7 Hz

J=7 HzJ=7 Hz

2H2H 2H2H

2H2H 3H3H 3H3H

Me-C=Me-C=

O-CHO-CH22-CH-CH33CH3O

OCH3

CH3

O O CH3

OO

CH3

CH3

CH3

CH3

OO

2.5 2.0 1.5

2.70

Scalar coupling: Coupling through bondScalar coupling: Coupling through bond

2nI + 12nI + 1 lines linesn = 0n = 0 11 22 33

445566

111 11 1

1 2 11 2 11 3 3 11 3 3 1

1 4 6 4 11 4 6 4 11 5 10 10 5 11 5 10 10 5 1

1 6 15 20 15 6 11 6 15 20 15 6 1CH3CH3

doubletdoublet

septetseptet

aabb

aa

bb



445566

111 11 1

1 2 11 2 11 3 3 11 3 3 1

1 4 6 4 11 4 6 4 11 5 10 10 5 11 5 10 10 5 1

1 6 15 20 15 6 11 6 15 20 15 6 1

2 x triplet2 x triplet

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0

3.40 3.30 3.20 3.10 3.00

Br

7.50 7.40 7.30 7.20 7.10 7.00

aa

aa

bb

bb

oo

oo

mm

mm

pp

pp



445566

111 11 1

1 2 11 2 11 3 3 11 3 3 1

1 4 6 4 11 4 6 4 11 5 10 10 5 11 5 10 10 5 1

1 6 15 20 15 6 11 6 15 20 15 6 1

2 x triplet2 x triplet1 quintet1 quintet

Br

3.0 2.5 2.0

aabb

cc

aa

bb

cc

CH2CH21.351.35

CH3CH3 CH2CH2 Roof effectRoof effect0.9 ppm0.9 ppm

4.0 3.5 3.0 2.5 2.0 1.5 1.0

Scalar coupling: Coupling through bond Scalar coupling: Coupling through bond C7 H14 O2 I = 7 -14/2 + 1 = 1C7 H14 O2 I = 7 -14/2 + 1 = 1 2nI + 12nI + 1 lines lines

n = 0n = 0 11 22 33

445566

111 11 1

1 2 11 2 11 3 3 11 3 3 1

1 4 6 4 11 4 6 4 11 5 10 10 5 11 5 10 10 5 1

1 6 15 20 15 6 11 6 15 20 15 6 1

2 x triplet2 x triplet Triplet:Triplet:

Quartet:Quartet:

Quintet:Quintet:Sixtet:Sixtet:

3H3H3H3H

(ppm)(ppm) IntInt multmult J (Hz) COMMENTJ (Hz) COMMENT0.90.9 3H3H triplettriplet 7 CH3->(7 CH3->(CH2CH2))1.11.1 3H3H triplettriplet 7 CH3->(7 CH3->(CH2CH2))1.351.35 2H2H sixtetsixtet 7 CH27 CH2 ( (CH3CH3, , CH2CH2))1.551.55 2H2H quintetquintet 7 CH27 CH2 ( (CH2CH2, , CH2CH2))2.32.3 2H2H quartetquartet 7 7 =C =C- - CH2CH2 ( (CH3CH3) ) 4.14.1 2H2H triplettriplet 77 CH2CH2 -O-O ( (CH2CH2))

CH2CH22.32.3 CH3CH3

1.11.1

2H2H 2H2H

2H2H

2H2H

CH2CH2 OO

OO

4.0 3.5 3.0 2.5 2.0 1.5 1.0



445566

111 11 1

1 2 11 2 11 3 3 11 3 3 1

1 4 6 4 11 4 6 4 11 5 10 10 5 11 5 10 10 5 1

1 6 15 20 15 6 11 6 15 20 15 6 1

2 x triplet2 x triplet6 6 11

CH31 2

3

4O 5

CH36

OTriplet:Triplet:

44Quartet:Quartet:

55 Quintet:Quintet:

33 Sixtet:Sixtet:

22

Common first order spin system Common first order spin system 2nI + 12nI + 1 lines lines

CC CC

HHaa HHbb

CC CC

HHaa HHbb

HHbb

CC CC

HHaa HHbb

CC

HHbb

CC CC

HHaa HHbb

HHbb

HHbb

CC CC

HHaa HHbb

HHbb

HHbb

CC

HHbb

HHbb

HHbb

Common first order spin system Common first order spin system 2nI + 12nI + 1 lines lines

CC CC

HHaa HHbb

HHb’b’

CC CC

HHaa HHbb

CC

HHb’b’

CC CCCC

HHbb

HHaa HHbb

HHbb

HHcc

JJabab = = JJab’ab’

JJabab JJabab

JJab’ab’

CC CC

HHaa HHbb

CC

HHb’b’

HHbb

CC CC

HHaa HHbb

CC

HHc’c’

HHb’b’

tdtd

qdqd

Geminal Geminal CouplingCoupling

Vicinal Vicinal CouplingCoupling

33J => tool 1J => tool 1

33J => Mestrec toolJ => Mestrec tool

33J => PerchJ => Perch

C:\NMR-programs\NMRSPIN\VICI.EXE

Using Vicinal Using Vicinal Coupling to establish Coupling to establish

isomerisomerJJaabb

JJaadd

HaHa

JJaacc

Long Range Long Range CouplingCoupling

Long Range couplingLong Range coupling

N

H1

H7

H5

H4 44JJH1-H3H1-H3 = 1.07 Hz = 1.07 Hz

55JJH1-H4H1-H4 = 1.21 Hz = 1.21 Hz55JJH1-H5H1-H5 = 0.95 Hz = 0.95 Hz55JJH4-H7H4-H7 = 0.67 Hz = 0.67 Hz

H

H

44JJH-HH-H = 1-2 Hz = 1-2 Hz

H

H

44JJH-HH-H = 1.1 Hz = 1.1 Hz

H C C C H

44JJH-HH-H = 9 Hz = 9 Hz

H C C C H


H C C C C H


H C C C C H


Spin System in Pople notationSpin System in Pople notationStructural UnitStructural Unit Spin systemSpin system Partial spectrumPartial spectrum

-CH-CH22-CH-CH33 AA33XX22

2.5 2.0 1.5

3.0 2.5 2.0 1.5

-CH-CH-CH-CH33 AA33XX

2.0 1.5 1.0

CHCH22-CH-CH22-CH-CH33 AA33MM22XX22

Each chemical shift is represented by a letter (far way letter for very Each chemical shift is represented by a letter (far way letter for very large shift difference – compare with the size of the coupling) large shift difference – compare with the size of the coupling)

Second Order spectra:Second Order spectra:AB instead of AXAB instead of AX

JJ JJJJ

AA andand BB : center of gravity of doublet : center of gravity of doublet

Chemical shiftChemical shift

= = (1-4) * (2-3) (1-4) * (2-3)

5.05.0

4.04.0

3.03.0

2.02.0

1.01.0

0.50.5

1 2 3 41 2 3 4As the difference in shift become smaller- As the difference in shift become smaller- compare with the size of the coupling the compare with the size of the coupling the outer peaks become smaller in intensityouter peaks become smaller in intensity

SpinWorks => load ABSpinWorks => load AB

AB-SpectraAB-Spectra

AMXAMX C6 H4 O5 N2C6 H4 O5 N2I = 6 - 4/2 + 2/2 +1I = 6 - 4/2 + 2/2 +1I = 6I = 6

Phenyl = Phenyl = 4 I4 INO2 = NO2 = 1 I1 I

AA22X and AX and A22BB

SpinWorks => load ASpinWorks => load A22BB

AMXAMX

AMXAMX

JJMetaMetaParaPara

JJOrthoOrthoMetaMeta

JJOrthoOrthoParaPara

H

H

H

7.58 ppm7.58 ppm

7.2 ppm7.2 ppm

6.83 ppm6.83 ppm

Substituants : Substituants : 2 OMe (~ 3.9 ppm)2 OMe (~ 3.9 ppm)CHO (~ 9.8 ppm)CHO (~ 9.8 ppm)

H

H

H

7.58 ppm7.58 ppm

7.2 ppm7.2 ppm

6.83 ppm6.83 ppm

CHOCHO

CHOCHO

OMeOMe

OMeOMe

OMeOMeOMeOMe

8.5 8.0 7.5

Br

N+

O-

O

HA

HB

HC

HD

Calculated shiftsCalculated shiftsHHAA=8.44 =8.44 HHBB=7.82 =7.82 HHCC=7.31 =7.31 HHDD=8.19 =8.19

HHAA

HHBBHHCCHHDD

meta bromo nitro benzene

AFMXAFMX

JJ

C5 H4 N BrC5 H4 N BrI = 5 – 4/2 – 1/2 +1/2 +1I = 5 – 4/2 – 1/2 +1/2 +1I = 4 (aromatic ring)I = 4 (aromatic ring)

Assignment of Assignment of 11H NMRH NMR of: of: cartilaginealcartilagineal

CHOCHO

MeMe

CHO-9CHO-9J = 2.0 HzJ = 2.0 Hz

H8

7

6

5

4

3

2

1

9

O H

H

ClCl

ClMe

H

H

H

H-1(s)H-1(s)

H8

7

R6

H

H

dddd

JJtranstrans=17 Hz=17 Hz

JJciscis=10.5=10.5 H-5 ddH-5 dd33JJ4,54,5 = 8.5 = 8.544JJ3,5 3,5 = 1.0= 1.0

H-4 ddH-4 dd

33JJ3,43,4=15.5=15.533JJ4,54,5 =8.5 =8.5

H-3 dddH-3 ddd33JJ3,43,4=15.5=15.544JJ3,53,5 =1.0 =1.044JJ4,94,9=2.0=2.0

Complicated proton spectra : CHComplicated proton spectra : CH33-CH-CH22-S-PF-S-PF22

Almost quintetAlmost quintet

tttt44JJFHFH

33JJHHHH33JJHHHH

33JJPHPH

Identifying Identifying 3131P P couplingscouplings

P

HH

{{3131P}P}

C C

H

P P

R

dddd

NMR – From Spectra to Structures An Experimental approachNMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-VerlagSecond edition (2007) Springler-VerlagTerence N. Mitchellm Burkhard CostisellaTerence N. Mitchellm Burkhard Costisella

Ph, 2HPh, 2H

CHCH33

1H1H1H1H CHCH22

Identifying Identifying 3131P couplings: another exampleP couplings: another example

NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-Verlag

Terence N. Mitchellm Burkhard Costisella

P31 NMRP31 NMR

Identifying Identifying 3131P couplings: another exampleP couplings: another example

H-nmr P31 decoupledH-nmr P31 decoupled

1H1H CHCH22

NMR – From Spectra to Structures An Experimental approachSecond edition (2007) Springler-VerlagTerence N. Mitchellm Burkhard Costisella

To identify a compound: PFTo identify a compound: PF221515NHSiNHSiHH33

Use as many techniques as possible

Proton nmr spectraProton nmr spectra is difficult to analyze with so many J’sis difficult to analyze with so many J’sBut withBut with 1919F, F, 1515NN andand 3131P P spectra it’s easier (get heteronuclear J)spectra it’s easier (get heteronuclear J)

To identify a compound: PFTo identify a compound: PF221515NHSiHNHSiH33

Use as many techniques as possible

Using decoupler : easier analysisUsing decoupler : easier analysis

Another example H{X}Another example H{X}Another example H{X}Another example H{X}

Changing the solventChanging the solvent

CDClCDCl33

CC66DD66

Changing solvent can be used to Changing solvent can be used to improve improve dispersion of chemical shiftsdispersion of chemical shifts

Changing the solventChanging the solvent

CH2

CH2

Me

OH Me=CH=CH22

CH-OHCH-OH

CHCH22

MeMe

CC66DD66

CH-OHCH-OH

=CH=CH22 CHCH22

ABABXXCDClCDCl33

DecouplingDecoupling

CH2

CH2

Me

OH Me=CH=CH22

CH-OHCH-OH

MeMe

CDClCDCl33

CHCH22

ABAB

CHCH22

ABABXX

Spin-Spin Spin-Spin DecouplingDecoupling

dqdq dqdq

dddd

Homo decouplingJJPHPH

JJHHHH


Decoupling Decoupling H-1H-1 glucose derivative glucose derivative

H-2H-2

H-1H-1

Several DecouplingSeveral Decoupling

NOENOEnOenOe

NOE: applying NOE: applying BB22 to the to the AA of an of an AAXX spin system spin system

XX11

XX22 AA22

AA11

XX11

XX22 AA22

AA11

{A}{A}

XX11 p = 2p = 2XX22 p = 2p = 2

XX11 p = 2p = 2XX22 p = 2p = 2

Immediately after irradiation, there is Immediately after irradiation, there is NO changeNO change in the in the intensity of Xintensity of XTurning on the Turning on the DecouplerDecoupler do not change population of the do not change population of the X transitionX transition

NOE: relaxation with double quantum pathway WNOE: relaxation with double quantum pathway W22 probability (positive NOE)probability (positive NOE)

XX11

XX22 AA22

AA11

{A}{A}

XX11

XX22 AA22

AA11

XX11 p = 2p = 2XX22 p = 2p = 2

XX11 p = 3p = 3XX22 p = 3p = 3

After After WW22 relaxation relaxation, there is a , there is a net increase in net increase in

the intensity of X (50%)the intensity of X (50%)

XX11

XX22 AA22

AA11

… … TT11

Dec. continueDec. continue

XX11

XX22 AA22

AA11

Relaxation takes time to establish a new equilibrium: TRelaxation takes time to establish a new equilibrium: T11 process process

delaydelay

WW22

NOE: Relaxation with zero quantum pathway WNOE: Relaxation with zero quantum pathway W00 probability (negative NOE)probability (negative NOE)

XX11

XX22 AA22

AA11

{A}{A}

XX11

XX22 AA22

AA11

XX11 p = 2p = 2XX22 p = 2p = 2

XX11 p = 1p = 1XX22 p = 1p = 1

After After WW00 relaxation relaxation, there is a net , there is a net decrease in decrease in

the intensity of X (50%) the intensity of X (50%) negative NOE negative NOE

XX11

XX22 AA22

AA11

… … TT11

Dec. continueDec. continue

XX11

XX22 AA22

AA11

Relaxation takes time to establish a new equilibrium: TRelaxation takes time to establish a new equilibrium: T11 process process

delaydelay

WW00WW00

NOE: summary of relaxation pathwaysNOE: summary of relaxation pathways

WW11: probability of single quantum : probability of single quantum

relaxation do not create nOerelaxation do not create nOe

A new population ditribution is generated A new population ditribution is generated by relaxation through dipole-dipole by relaxation through dipole-dipole

relaxation : double quantum and zero relaxation : double quantum and zero quantum pathway quantum pathway WW22 and and WW00

If If WW2 2 is efficientis efficient ( (small molecule – fast motion small molecule – fast motion large frequency large frequency ))

Level Level increase increase level level increase also with decoupler continuing increase also with decoupler continuing

XX11

XX22 AA22

AA11

WW22WW00

WW22 pathway yield positive nOe pathway yield positive nOe

If If WW0 0 is efficientis efficient ( (large molecule – slow motion large molecule – slow motion small freq. Diff.small freq. Diff.))

Level Level increase increase level level increase also with decoupler continuing increase also with decoupler continuing

WW00 pathway yield negative nOe pathway yield negative nOe

NOE is a kinetic effect: need delay ~ TNOE is a kinetic effect: need delay ~ T11

It take time to developIt take time to develop It takes time to decayIt takes time to decay

NOE difference: nOe-dNOE difference: nOe-d

d1d1 AQAQ

Dec on frqDec on frq

d1d1 AQAQ

Dec off frqDec off frq

CC CCClCl

HH

MeMe

MeMe

irrirr

differencedifference

irrirr controlcontrol

nOenOe

NOENOE

COOH

HCH3

CH3

{Me –cis} => +19%{Me –cis} => +19%

{Me –trans} => -2%{Me –trans} => -2%

{Ha} => +45%{Ha} => +45%

2

3

1

4

6

5

OH

CH3

Ph

H

OMe

H

H

H6H6H5H5

2

3

1

4

6

5

OMe

CH3

Ph

H

OH

H

H

Choosing a structure by nOeChoosing a structure by nOe

H3H3

{OMe}{OMe}

{OH}{OH}

O

O

CH

O

P

CH3

CH3

Cl

Cl

NOEd


NOEd exampleNOEd example

Organometallic compoundsOrganometallic compounds Proton - NMRProton - NMR Increasing the 1 s orbital density increases the shieldingIncreasing the 1 s orbital density increases the shielding

M = CM = C M = SiM = Si M = GeM = Ge

MH4 0.10.1 3.23.2 3.13.1

MH3I 2.02.0 3.43.4 3.53.5

MH3Br 2.52.5 4.24.2 4.54.5

MH3Cl 2.82.8 4.64.6 5.15.1

(MH3)2O 3.23.2 4.64.6 5.35.3

MH3F 4.14.1 4.84.8 5.75.7

Shift to low field when the metal is heavier (Shift to low field when the metal is heavier (SnHSnH44 - - = 3.9 ppm = 3.9 ppm))

Proton – NMR : Chemical shiftProton – NMR : Chemical shift

• Further contribution to shielding / deshieldingshielding / deshielding is the anisotropicanisotropic magnetic susceptibility from neighboring groups (e.g. AlkenesAlkenes, Aromatic ringsAromatic rings -> deshielding in the plane of the bound)

• In transition metal complexes there are often low-lying excited electronic states. When magnetic field is applied, it has the effect of mixing these to some extent with the ground state.

• Therefore the Therefore the paramagnetic term is important for those nuclei themselvesparamagnetic term is important for those nuclei themselves => => large high frequency shifts (low field).large high frequency shifts (low field). The protonsprotons bound to these will be bound to these will be shielded (shielded ( => 0 to -40 ppm => 0 to -40 ppm)) (these resonances are good diagnostic. )

• For transition metal hydride this range should be extended to 70 ppm!For transition metal hydride this range should be extended to 70 ppm!

• If paramagnetic species are to be included, the range can go to 1000 ppm!!If paramagnetic species are to be included, the range can go to 1000 ppm!!

Exchange : DNMR – Dynamic NMRExchange : DNMR – Dynamic NMRNMR is a convenient way to study rate of reactions – provided that the lifetime of participating species are comparable to NMR time scale (1010-5-5 s s)

H

H

H

H

H

GeMe3

At low temperature, hydrogens form an A2B2XA2B2X spin system

At higher temperature germaniumgermanium hop from one C to the next

Index NMR-basicsNMR-basicsNMR-basicsNMR-basics NMR-SymmetryNMR-Symmetry

2-NMR-H

Documents

Transcript of 2-NMR-H