C5H4N4





 








 








Nitrogen

Nuclear Quadrupole Coupling Constants


in Purine


 


















Nitrogen nqcc's in each of the following tautomers of purine were determined by Favero et al. [1]. 












N(9)H

N(7)H









































Note: At the B3LYP/cc-pVTZ level of theory, EN(9)H < EN(7)H by 15.7 kJ/mole.

 








Calculation of the nitrogen nqcc tensors in each tautomer was made here on molecular ropt structures given by B3P86/6-31G(3d,3p) and B3LYP/cc-pVTZ optimization.  Calculated and experimental nqcc's are compared in Tables 1 and 2.  Structure parameters are given in Z-matrix format in Table 3, rotational constants in Table 4.

 








In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's.

 








 








 
 







Table 1.  14N nqcc's in N(9)H-Purine (MHz).  Calculation was made on molecular structures given by (1) B3P86/6-31G(3d,3p) and (2) B3LYP/cc-pVTZ optimization.
 
 










Calc (1)
Calc (2)
Expt. [1]
 









N(1)
 Xaa
 -
 3.359
 -
 3.361
 -
 3.343(5)


Xbb
0.409
0.395
0.440(6)


Xcc
2.949
2.965
2.904(6)


|Xab|
2.539
2.567




 








RMS
0.033 (1.5 %)
0.045(2.0 %)




 







N(3)
 Xaa
1.724
1.754
1.673(7)


Xbb -
 4.205
 -
 4.257
 -
 4.229(9)


Xcc
2.481
2.504
2.555(9)


|Xab|
0.070
0.062














RMS
0.053 (1.9 %)
0.058 (2.0 %)













N(7)
 Xaa
1.457
1.486
1.547(7)


Xbb -
 3.384
 -
 3.435
 -
 3.379(9)


Xcc
1.927
1.949
1.833(9)


|Xab|
1.684
1.677




 








RMS
0.075 (3.3 %)
0.082 (3.6 %)













N(9) Xaa
1.423
1.460
1.489(5)


Xbb
1.505
1.501
1.495(7)


Xcc -
 2.928
 -
 2.961
 -
 2.985(7)


|Xab|
0.093
0.082




 








RMS
0.051 (2.6 %)
0.022 (1.1 %)




 








 








 








 
 







Table 2.  14N nqcc's in N(7)H-Purine (MHz).  Calculation was made on molecular structures given by (1) B3P86/6-31G(3d,3p) and (2) B3LYP/cc-pVTZ optimization.
 
 










Calc (1)
Calc (2)
Expt. [1]
 









N(1)
 Xaa
 -
 3.394
 -
 3.394
 -
 3.560(15)


Xbb
0.406
0.386
0.566(17)


Xcc
2.988
3.008
2.994(17)


|Xab|
2.482
2.512




 








RMS
0.133 (5.6 %)
0.142 (6.0 %)




 







N(3)
 Xaa
1.498
1.525
0.695(11)


Xbb -
 4.547
 -
 4.592
 -
 2.744(20)


Xcc
3.049
3.067
2.049(20)


|Xab|
0.053
0.051














RMS
1.278 (70. %)
1.309 (72. %)













N(7)
 Xaa
1.633
1.660
1.254(11)


Xbb
1.516
1.511
1.532(16)


Xcc -
 3.149
 -
 3.171
 -
 2.786(16)


|Xab|
0.104
0.094




 








RMS
0.303 (16. %)
0.323 (17. %)













N(9) Xaa
1.414
1.448
1.541(11)


Xbb -
 3.417
 -
 3.460
 -
 3.239(18)


Xcc
2.002
2.011
1.699(18)


|Xab|
1.593
1.591




 








RMS
0.216 (10. %)
0.227 (11. %)




 








 








 








 




Table 3. Purine.  B3P86/6-31G(3d,3p) and B3LYP/cc-pVTZ optimized structure parameters (Å and degrees).
 





N(9)H-Purine








 N
 C,1,B1
 N,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,4,B4,3,A3,2,D2,0
 C,1,B5,2,A4,3,D3,0
 N,5,B6,4,A5,3,D4,0
 C,7,B7,5,A6,4,D5,0
 N,4,B8,3,A7,2,D6,0
 H,6,B9,1,A8,2,D7,0
 H,2,B10,1,A9,6,D8,0
 H,9,B11,4,A10,3,D9,0
 H,8,B12,7,A11,5,D10,0








      B3P86     B3LYP









 B1=1.34018716
 B2=1.33361482
 B3=1.32396995
 B4=1.4065379
 B5=1.33210523
 B6=1.38183015
 B7=1.30435543
 B8=1.37019535
 B9=1.0871013
 B10=1.08661132
 B11=1.00764351
 B12=1.08182061
 A1=128.15393261
 A2=111.95780356
 A3=126.31878907
 A4=118.10942545
 A5=110.79274931
 A6=103.98329094
 A7=128.83302596
 A8=117.72998414
 A9=115.87473653
 A10=126.25144149
 A11=124.92063604
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=0.
 D6=180.
 D7=180.
 D8=180.
 D9=0.
 D10=180.
  B1=1.3404516
 B2=1.33438602
 B3=1.32366658
 B4=1.40689741
 B5=1.33266026
 B6=1.38480572
 B7=1.3024722
 B8=1.37188084
 B9=1.08394687
 B10=1.08289476
 B11=1.00578446
 B12=1.07855631
 A1=127.75602476
 A2=112.40182625
 A3=125.95608221
 A4=118.30281346
 A5=110.5382445
 A6=104.32489424
 A7=129.0887004
 A8=117.92013088
 A9=116.07272228
 A10=126.23238158
 A11=125.02571649
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=0.
 D6=180.
 D7=180.
 D8=180.
 D9=0.
 D10=180.

 




 




N(7)H-Purine








 N
 C,1,B1
 N,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,4,B4,3,A3,2,D2,0
 C,1,B5,2,A4,3,D3,0
 N,5,B6,4,A5,3,D4,0
 C,7,B7,5,A6,4,D5,0
 N,4,B8,3,A7,2,D6,0
 H,6,B9,1,A8,2,D7,0
 H,2,B10,1,A9,6,D8,0
 H,8,B11,7,A10,5,D9,0
 H,7,B12,5,A11,4,D10,0








      B3P86     B3LYP








 B1=1.34402774
 B2=1.32785913
 B3=1.33144802
 B4=1.41134427
 B5=1.32911903
 B6=1.37494472
 B7=1.3694113
 B8=1.37769893
 B9=1.08799882
 B10=1.08683695
 B11=1.08210476
 B12=1.00685921
 A1=128.40634775
 A2=113.79141511
 A3=122.47138986
 A4=117.75419496
 A5=104.88811142
 A6=106.11144551
 A7=127.01777042
 A8=117.6273941
 A9=115.39209838
 A10=120.92025216
 A11=127.53830998
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=0.
 D6=180.
 D7=180.
 D8=180.
 D9=180.
 D10=180.
  B1=1.34462946
 B2=1.32811409
 B3=1.33108314
 B4=1.41156991
 B5=1.32923724
 B6=1.37790796
 B7=1.37176593
 B8=1.37993795
 B9=1.08488941
 B10=1.08310153
 B11=1.07876939
 B12=1.00497577
 A1=128.00402331
 A2=114.14710917
 A3=122.32293713
 A4=117.94878742
 A5=104.93826577
 A6=106.12619826
 A7=127.35962229
 A8=117.74018185
 A9=115.58496031
 A10=121.03463241
 A11=127.53156531
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=0.
 D6=180.
 D7=180.
 D8=180.
 D9=180.
 D10=180.

 





 








 



Table 4.  Purine.  Rotational Constants (MHz).  Calc on (1) B3P86/6-31G(3d,3p) and (2) B3LYP/cc-pVTZ optimized molecular structure.







Calc (1)
 Calc (2)
   Expt. [1]





   N(9)H A
   4157.
   4163.
 4125.8895(2)

B
   1765.
   1760.
 1755.1720(1)

C
   1239.
   1237.
 1231.55819(6)





   N(7)H A
   4160.
   4166.
 4127.3813(3)

B
   1761.
   1756.
 1749.7594(3)

C
   1237.
   1235.
 1229.42760(7)



  








[1] L.B.Favero, I.Uriarte, L.Spada, P.Ecija, C.K.Calabrese, W.Caminati, and E.J.Cocinero, J.Phys.Chem.Lett. 7(7),1107(2016).

 








 








Pyrimidine
Imidazole
 Pyrrole
 Pyridine











 








Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 14 March 2016