3,6-Dioxo-2,3,4,6-tetrahydropyrazino
[2,1-a]isoindole-1-carbonitrile

NMRanalyst Sample Application
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Sample Description:

 Molecular Formula: C12H7N3O2
Molecular Weight: 225.203
InChI= 1/C12H7N3O2/c13-5-9-11-7-3-1-2-4-8(7)12(17)15(11)6-10(16)14-9/h1-4H,6H2,
(H,14,16)/f/h14H
IUPAC Name:  3,6-Dioxo-2,3,4,6-tetrahydropyrazino[2,1-a]isoindole-1-carbonitrile
PubChem: 5326134
NMRShiftDB: 30000160
Spectrometer: Bruker AMX 400 MHz
Solvent: DMSO-d6
Provided by:  Institut Organische Chemie, Universitaet Mainz (inhouse database)

DirectorynpF2NSswF2spF2npF1swF1spF1time
proton (1)16384326410.256-1197.4991 m 54 s
carbon (2)16384940025000.000-1418.6112 h 45 m
cosy (3)102484032.258-108.4961284032.258-108.4961 h 8 m
edited hmqc (4)1024124032.258-358.49712818111.960-958.8482 h 8 m
hmbc (5)1024124032.258-358.49725620126.000-978.4002 h 8 m


1D Proton Spectrum:

1D Proton Spectrum


1D Carbon Spectrum (Deuterated Solvent Resonances Subtracted):

1D Carbon Spectrum


 

Automated VerifyIt Proton Assignments:

Proton Assignments
 

Automated VerifyIt Carbon Assignments:

Carbon Assignments

Top 10 FindIt Molecular Structures Consistent With Molecular Formula and Proton Resonances:

The correct structure is at position 1.

FindIt Structures

 Best 10 structures in decreasing rating (structure ID shown in parentheses):
    1: 0.970239 ( 5326134)    2: 0.950590 ( 5449437)    3: 0.935907 ( 5826209)
    4: 0.920151 ( 9915180)    5: 0.913847 ( 4808231)    6: 0.912755 (  478015)
    7: 0.910040 (  338713)    8: 0.908638 (  377858)    9: 0.899773 (  478013)
   10: 0.882169 (   38763)
			

Top 10 FindIt Molecular Structures Consistent With Proton and Carbon Resonances:

The correct structure is at position 4.

FindIt Structures

 Best 10 structures in decreasing rating (structure ID shown in parentheses):
    1: 0.887457 (  571723)    2: 0.886694 ( 1989871)    3: 0.885365 (  579568)
    4: 0.883699 ( 5326134)    5: 0.881755 (  336572)    6: 0.876942 ( 5101376)
    7: 0.875227 ( 2192104)    8: 0.874190 (  457779)    9: 0.873735 ( 2304925)
   10: 0.872759 ( 4963662)
			

2D Multiplicity-Edited HMQC Spectrum:

2D Multiplicity-Edited HMQC Spectrum

Determined HMQC Correlations:

Determined HMQC Correlations

Top 10 FindIt Molecular Structures Consistent With Molecular Formula, Proton Resonances, and Protonated Carbon (HMQC) Resonances:

The correct structure is at position 1.

FindIt Structures

 Best 10 structures in decreasing rating (structure ID shown in parentheses):
    1: 0.894112 ( 9255836)    2: 0.889289 (  571723)    3: 0.884899 ( 5326134)
    4: 0.882889 ( 1989871)    5: 0.879791 (  615894)    6: 0.878052 (  336572)
    7: 0.875647 (  457779)    8: 0.875638 ( 2304925)    9: 0.873523 ( 3263189)
   10: 0.872633 ( 4963662)
			

2D (DQF?) COSY Spectrum:

2D (DQF?) COSY Spectrum

AssembleIt HMQC & (DQF?) COSY Derived Carbon-Carbon Correlations:

AssembleIt HMQC & (DQF?) COSY Derived Correlations

2D HMBC Spectrum:

2D HMBC Spectrum

AssembleIt HSQC (HMQC), HMBC & DQF-COSY Derived Correlations:

AssembleIt Derived Correlations

Comments:

The 11 ppm proton resonance (corresponding to a 0.91 H integral) originates from the NH in proximity to the CN group. FindIt identifies the correct structure with molecular formula and proton resonances.

In the carbon spectrum, the undetected resonance around 110 ppm is the middle of the spectrum glitch and should not be detected. The "cosygs" pulse sequence used is not a phase sensitive one as recommended. It also does not appear to be a DQF filtered one. Due to a F1 resolution worse than 30 Hz/point, the sinc wiggles extend far in the F1 dimension. Various weighting functions might limit these ridges. But this would not help the determination of the coupling constants, which is essential to distinguish 3-bond from longer range proton-proton correlations in a DQF-COSY spectrum. This spectrum probably should not be used. But it identifies the three bonds between protonated carbons of this molecule.


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