4-CHO-C5H4N


 

 








Nitrogen


Nuclear Quadrupole Coupling Constants


in 4-Pyridine Carbaldehyde


 







 

 


 




The molecular structure of 4-pyridine carbaldehyde was optimized at the B3P86/6-31G(3d,3p) level of theory.  Cs symmetry was assumed.  On this structure calculation was made of the nitrogen nqcc's.  These are compared with the experimental nqcc's of Stryjewski et al. [1] in Table 1.  Structure parameters are given in Table 2, atomic coordinates in Table 3, rotational constants in Table 4.
 
In Table 1, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
RMS is the root mean square differene between calculated and experimental nqcc's (percent of average experimental nqcc).  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's.
 

 







   







Table 1.  Nitrogen nqcc's in 4-Pyridine Carbaldehyde (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 




Calc.
Expt. [1]
   






14N Xaa - 4.915 - 4.900(8)
Xbb 1.163 1.179(9)
Xcc 3.752 3.721(9)
|Xab| 1.131
 
RMS 0.022 (0.7 %)
RSD 0.030 (1.3 %)
 
  Xxx 1.367 1.383 *
Xyy 3.752 3.721
Xzz - 5.119 - 5.104
ETA 0.466 0.458
Øz,a 10.21 10.20
Øa,bi 10.12 10.12
Øz,bi **   0.08   0.08
 
 
* Calculated here from the experimental diagonal nqcc's and the calculated off-diagonal nqcc.
** The z-axis makes an angle of 0.08o with the external bisector ( 'bi' ) of the C(6)N(1)C(2) angle, and tilts toward C(2).
 
 
 
Table 2.  4-Pyridine Carbaldehyde and Pyridine.  Molecular structure parameters, ropt (Å and degrees).
 
4-CHO-Pyridine Pyridine
N(1)C(2) 1.3366 1.3336
C(2)C(3) 1.3869 1.3904
C(3)C(4) 1.3936 1.3885
C(4)C(5) 1.3910 1.3885
C(5)C(6) 1.3908 1.3904
C(6)N(1) 1.3319 1.3336
C(2)H(2) 1.0871 1.0880
C(3)H(3) 1.0841 1.0845
C(5)H(5) 1.0859 1.0845
C(6)H(6) 1.0872 1.0880
C(6)N(1)C(2) 117.54 117.03
N(1)C(2)C(3) 123.72 123.80
C(2)C(3)C(4) 118.19 118.44
C(3)C(4)C(5) 118.66 118.50
C(4)C(5)C(6) 118.48 118.44
C(5)C(6)N(1) 123.41 123.80
N(1)C(2)H(2) 115.85 115.94
C(2)C(3)H(3) 121.85 120.21
C(6)C(5)H(5) 120.69 120.21
N(1)C(6)H(6) 116.10 115.94
 
C(4)C 1.4813
CO 1.2069
CH 1.1111
C(3)C(4)C 121.10
C(4)C=O 124.14
C(4)CH 114.79


 
 
Table 3.  4-Pyridine Carbaldehyde.  Atomic coordinates, ropt.
 
 a (Å)  b (Å)
N(1) - 2.2384 - 0.2577
C(2) - 1.3554 - 1.2611
C(3) 0.0191 - 1.0770
C(4) 0.5085 0.2278
C(5) - 0.4000 1.2812
C(6) - 1.7588 0.9848
H(2) - 1.7767 - 2.2632
H(3) 0.7084 - 1.9138
H(5) - 0.0574 2.3116
H(6) - 2.4974 1.7826
C 1.9648 0.4987
O 2.8134 - 0.3594
H 2.2384 1.5756
 
 

Table 4.  4-Pyridine Carbaldehyde.  Rotational Constants (MHz).
 
Calc ropt   Expt. [1]
A 5560.6 5519.114(3)
B 1568.0 1559.205(2)
C 1223.1 1216.129(2)


 
 
[1] D.Stryjewski, N.Heineking, and H.Dreizler, Z.Naturforsch. 44a,67(1989).
See also ...
K.Georgiou and G.Roussy, J.Mol.Spectrosc. 82,176(1980).
 
 

Pyridine 2-Pyridine Carbaldehyde 3-Pyridine Carbaldehyde

4-Fluoropyridine 4-Chloropyridine 4-Bromopyridine
4-Cyanopyridine 4-Methylpyridine
 
 

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Last Modified 17 Nov 2003