m-C6H4CH3CN

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Nitrogen

Nuclear Quadrupole Coupling Constants


in meta-Tolunitrile


 







 

 

 




Nitrogen nqcc's in m-tolunitrile were determined by Bruhn and Mäder [1].
 
Calculation of the nqcc's was made here on molecular structures given by B3P86/6-31G(3d,3p) optimization with the CH bond in the Cs plane I) pointing away from CN, and II) pointing toward CN.  These calculated nqcc's are compared with the experimental values in Tables 1 and 2.  Conformer II structure parameters and atomic coordinates are given in Tables 3 and 4, rotational constants in Table 5.
 
For both the B3P86/6-31G(3d,3p) and the B3PW91/6-311+G(df,pd) models, EII < EI by 43 cal/mol.
 
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.  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 of the magnitudes of the 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 m-Tolunitrile, conformer I (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 




Calc.
Expt. [1]
   





14N Xaa - 3.626 - 3.6263(8)
Xbb 1.701 1.6837(10)
Xcc 1.925 1.9426(10)
|Xab| 1.884 1.8700(27)
 
RMS 0.014 (0.6 %)
RSD 0.030 (1.3 %)
 
  Xxx 2.300 2.2761(25)
Xyy 1.925 1.9426(10)
Xzz - 4.224 - 4.2188(23)
ETA - 0.089 - 0.079
Øz,a 17.64 17.58(2)
Øa,CN 17.63
Øz,CN   0.01
 
 
 
   






Table 2. Nitrogen nqcc's in m-Tolunitrile, conformer II (MHz).  Calculation was made on the B3P86/6-31G(3d,3p) ropt structure.
 




Calc.
Expt. [1]
   





14N Xaa - 3.627 - 3.6263(8)
Xbb 1.705 1.6837(10)
Xcc 1.921 1.9426(10)
|Xab| 1.881 1.8700(27)
 
RMS 0.018 (0.7 %)
RSD 0.030 (1.3 %)
 
  Xxx 2.302 2.2761(25)
Xyy 1.921 1.9426(10)
Xzz - 4.223 - 4.2188(23)
ETA - 0.090 - 0.079
Øz,a 17.60 17.58(2)
Øa,CN 17.60
Øz,CN   0.00
 
 
 
 
Table 3.  m-Tolunitrile, conformer II.  Molecular structure parameters, ropt (Å and degrees).
   
C(1)C(2) 1.3906 C(1)C(2)C(3) 120.72
C(2)C(3) 1.3992 C(2)C(3)C(4) 120.37
C(3)C(4) 1.3964 C(3)C(4)C(5) 119.05
C(4)C(5) 1.3877 C(4)C(5)C(6) 120.33
C(5)C(6) 1.3888 C(5)C(6)C(1) 121.28
C(6)C(1)C(2) 118.25
 
C(2)H(2) 1.0847 C(1)C(2)H(2) 120.16
C(4)H(4) 1.0834 C(3)C(4)H(4) 119.84
C(5)H(5) 1.0845 C(4)C(5)H(5) 119.74
C(6)H(6) 1.0861 C(5)C(6)H(6) 119.49
 
C(1)C(Me) 1.5017 C(2)C(1)C(Me) 121.02
C(Me)H(7) 1.0913 C(1)C(Me)H(7) 111.37
C(Me)H(8) 1.0939 C(1)C(Me)H(8) 111.12
C(Me)H(9) 1.0939 C(1)C(Me)H(9) 111.12
H(7)C(Me)H(8) 107.94
H(7)C(Me)H(9) 107.94
H(8)C(Me)H(9) 107.18
 
C(3)C(cy) 1.4293 C(2)C(3)C(cy) 119.70
C(cy)N 1.1582 C(3)C(cy)N 180.01
 
For comparison, the B3P86/6-31G(3d,3p) optimized molecular structure of benzene is CC = 1.3909 Å and CH = 1.0851 Å.


 
 
Table 4.  m-Tolunitrile, conformer II.  Atomic coordinates, ropt.
 
 a (Å)  b (Å)  c (Å)
C(1) - 1.4769 0.4917
C(2) - 0.1442 - 0.8888
C(3) 0.8843 - 0.0599
C(4) 0.5862 - 1.4242
C(5) - 0.7428 - 1.8235
C(6) - 1.7594 - 0.8774
H(2) 0.1103 1.9432
H(4) 1.3892 - 2.1514
H(5) - 0.9870 - 2.8801
H(6) - 2.7949 - 1.2052
C(Me) - 2.5861 1.5041
H(7) - 2.1948 2.5228
H(8,9) - 3.2250 1.3887 ± 0.8803
C(cy) 2.2466 0.3725
N 3.3506 0.7227
 
 
Table 5.  m-Tolunitrile, conformer II.  Rotational Constants (MHz).
 
Calc. ropt    Expt. [1]
A  3320.8 3295.9103(10)
B  1203.5 1199.1182(2)
C    888.2   883.9223(1)
 
 
[1] T.Bruhn and H.Mäder, J.Mol.Spectrosc. 200,151(2000).
 
 

Benzonitrile o-Fluorobenzonitrile

o-Tolunitrile m-Fluorobenzonitrile
p-Tolunitrile p-Fluorobenzonitrile
 
 

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Molecules/Nitrogen



 

 













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Last Modified 17 June 2004