Uracil



















 




 








Nitrogen

Nuclear Quadrupole Coupling Constants

in Uracil

 








 








 








Nitrogen nqcc's in uracil were determined by Vaquero et al. [1], and by Brünken et al. [2].  A heavy atom substitution structure was determined by Vaquero et al. [1].  A best estimate ab initio equilibrium structure was determined by Puzzarini and Barone [3], and a semi-experimental equilibrium structure by Császár et al. [4].

 








Calculation of the 14N nqcc tensors was made here on the reSE molecular structure of Császár et al. [4].  Calculated and experimental [1] nqcc's are compared in Tables 1 and 2.  Structure parameters are given in Z-matrix format in Table 3.

 








Calculation was made with both B3PW91/6-311+G(df,pd) and B3PW91/6-311+G(d,p) models.

 








In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  ETA = (Xxx - Xyy)/Xzz.

RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation model for calculation of nitrogen efg's/nqcc's.

 








 








   







Table 1.  14N(1) nqcc's in Uracil (MHz).  Calculation was made on the reSE molecular structure with both (1) B3PW91/6-311+G(df,pd) and (2) B3PW91/6-311+G(d,p) models.
   









Calc (1)
Calc (2)
Expt. [1]
   







Xaa
1.729
1.800
1.7672(68)

Xbb
1.864
1.955
1.9748(83)

Xcc -
 3.593 - 3.755
 - 3.7420(83)

|Xab|
0.144
0.163



 







RMS
0.109 (4.4 %)
0.023 (0.93 %)


RSD
0.030 (1.3 %)
0.086 (3.8 %)


 







Xxx
1.637
1.697



Xyy
1.956
2.058



Xzz -
 3.593 - 3.755



ETA
0.088
0.096



 








 








 







   







Table 2.  14N(3) nqcc's in Uracil (MHz).  Calculation was made on the reSE molecular structure with both (1) B3PW91/6-311+G(df,pd) and (2) B3PW91/6-311+G(d,p) models.
   









Calc (1)
Calc (2)
Expt. [1]
   







Xaa
1.860
1.960
1.9161(68)

Xbb
1.487
1.540
1.5344(90)

Xcc -
 3.347 - 3.500
 - 3.4505(90)

|Xab|
0.154
0.157



 







RMS
0.073 (3.2 %)
0.038 (1.7 %)


RSD
0.030 (1.3 %)
0.086 (3.8 %)


 







Xxx
1.432
1.487



Xyy
1.915
2.013



Xzz -
 3.347 - 3.500



ETA
0.144
0.150



 


















 














Table 3.  Uracil.  Structure parameters, reSE [4] (Ĺ and degrees).
 













 N
 C,1,R1
 N,2,R2,1,A1
 C,3,R3,2,A2,1,D1,0
 C,4,R4,3,A3,2,D2,0
 C,1,R5,2,A4,3,D3,0
 O,2,R6,1,A5,6,D4,0
 O,4,R7,3,A6,2,D5,0
 H,1,R8,2,A7,3,D6,0
 H,3,R9,4,A8,5,D7,0
 H,5,R10,6,A9,1,D8,0
 H,6,R11,1,A10,2,D9,0





 R1=1.3810
 R2=1.3749
 R3=1.3991
 R4=1.4548
 R5=1.3722
 R6=1.2101
 R7=1.2186
 R8=1.0043
 R9=1.0083
 R10=1.0757
 R11=1.0781
 A1=113.38
 A2=127.97
 A3=113.75
 A4=123.39
 A5=122.78
 A6=120.41
 A7=115.14
 A8=116.41
 A9=122.12
 A10=115.39
 D1=0.
 D2=0.
 D3=0.
 D4=180.
 D5=180.
 D6=180.
 D7=180.
 D8=180.
 D9=180.






 








 








[1] V.Vaquero, M.E.Sanz, J.C.López, and J.L.Alonso, J.Phys.Chem. A Letters, 111,3443(2007).

[2] S.Brünken, M.C.McCarthy, P.Thaddeus, P.D.Godfrey, and R.D.Brown, A&A 459,317(2006).

[3] C.Puzzarini and V.Barone, PCCP, 13,7158(2011).  This work includes also a high level CCSD(T) calculation of the nqcc's.

[4] A.G.Császár, J.Demaison, and H.D.Rudolph, J.Phys.Chem. A, 119(9),1731(2015).

 








 








Pyridine Pyrimidine Quinoline Isoquinoline

2-Pyridone 2-Hydroxypyridine
Thymine

 








 








Table of Contents




Molecules/Nitrogen




 








 













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Last Modified 1 July 2015