Quinazoline




 




 

Nitrogen


Nuclear Quadrupole Coupling Constants


in Quinazoline


 







 
Nitrogen nqcc tensors in quinazoline were calculated on a molecular structure optimized at the B3P86/6-31G(3d,3p) level of theory (ropt).  These calculated nqcc's are compared with the experimental values of McNaughton et al. [1] in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants and electric dipole moments in Table 4.
 
In Tables 1 and 2, subscripts a,b,c refer to principal axes of the inertia tensor, subscripts x,y,z to principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the plane of the molecule.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
RMS is the root mean square difference between calculated and experimental nqcc's (percentage of average experimental nqcc).  RSD is the residual stand deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's (which may be taken as the uncertainty in calculated nqcc's, notwithstanding uncertainties in the calculated molecular structure).
 
 
   







Table 1. 14N(15) nqcc's in Quinazoline (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.  This is N(1) in Ref. [1].
   










Calc.
Expt. [1]
   






14N(15) Xaa 1.462 1.4547(35)
Xbb - 4.533 - 4.5186 *
Xcc 3.071 3.0639 *
Xab - 0.219
 
RMS 0.010 (0.34 %)
RSD 0.030 (1.3 %)
 
Xxx 1.470
Xyy 3.071
Xzz - 4.541
ETA 0.353
Øz,b 2.09
Øb,bi 1.39
Øz,bi** 3.48
 
 
* Calculated here from experimental Xaa and Xbb - Xcc = -7.5826(75) MHz.
** The z-axis makes an angle of 3.48o with the external bisector ('bi') of the CNC angle and tilts toward C(4).  See Table 3 for atomic numbering.
 
 
   







Table 2. 14N(16) nqcc's in Quinazoline (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.  This is N(2) in Ref. [1].
   










Calc.
Expt. [1]
   






14N(16) Xaa - 3.561 - 3.59205(179)
Xbb - 0.321 - 0.3503 *
Xcc 3.241 3.2417 *
Xab - 2.368
 
RMS 0.025 (1.0 %)
RSD 0.030 (1.3 %)
 
Xxx 1.442
Xyy 3.241
Xzz - 4.682
ETA 0.384
Øz,a 25.33
Øa,bi 27.41
Øz,bi**   2.08
 
 
* Calculated here from experimental Xaa and Xbb - Xcc = -2.8914(62) MHz.
** The z-axis makes an angle of 2.08o with the external bisector ('bi') of the CNC angle and tilts toward C(13).  See Table 3 for atomic numbering.
 
 
Table 3. Quinazoline and Pyrimidine.  Selected molecular structure parameters, B3P86/6-31G(3d,3p) ropt (Å and degrees).  The complete structure of quinazoline is given here in Z-matrix format.
 
Quinazoline Pyrimidine
 
C(4)N(15) 1.3599 1.3328
N(15)C(13) 1.3093 1.3320
C(13)N(16) 1.3580 1.3320
N(16)C(10) 1.3116 1.3328
C(4)N(15)C(13) 116.38 115.70
N(15)C(13)N(16) 127.89 127.38
C(13)N(16)C(10) 115.81 115.70
 
 
 
Table 4.  Quinazoline, ropt.  Rotational constants (MHz) and B3PW91/6-311+G(df,pd) calculated dipole moments (D).
 
 Calc.     Expt. [1]
A 3253.20 3229.85422(55)
B 1283.94 1276.2106327(191)
C   920.60   914.9869715(217)
a|   2.85
b|   1.24
 
 
[1] D.McNaughton, P.D.Godfrey, M.K.Jahn, D.A.Dewald, and J.-U.Grabow, J.Chem.Phys. 134,154305(2011).

 








 







Pyrimidine Phthalazine Quinoxaline 1,10-Phenanthroline
Acridine Quinoline Isoquinoline Phenanthridine
 

 








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Molecules/Nitrogen
 

 













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Last Modified 20 April 2011