CH3CHBrCH2CH3
































 









Bromine


Nuclear Quadrupole Coupling Constants

in 2-Bromobutane, G+


 








  A  Conformer
G-  Conformer













Calculation of the bromine nqcc tensors was made here on molecular structures given by MP/6-311+G(3df,3pd) optimization, and on these same structure but with empirically corrected approximate equilibrium C-C and CBr bond lengths.  These calculated nqcc's are compared with the experimental values in Tables 1 and 2.  Structure parameters are given 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; x,y,z to the principal axes of the nqcc tensor.  ETA = (Xxx - Xyy)/Xzz.  Øz,CBr (degrees) is the angle between the z-principal axis and the CCl bond direction.

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 of the B1LYP/TZV(3df,3p) model for calculation of the efg's/nqcc's.  

 








 








   








Table 1.  79Br nqcc's in 2-Bromobutane, G+ (MHz).  

 







Calc (1) was made on the MP2/6-311+G(3df,3pd) optimized molecular structure.

Calc (2) was made on this same structure but with empirically corrected C-C and CBr bond lengths.

 









Calc (1)
Calc (2)
Expt. [1]
   








Xaa
304.09

306.93

300.1367(2)


Xbb
- 83.07

- 85.69

- 82.2620 *


Xcc -
221.01
-
221.24
-
217.8747 *


Xab -
324.64
-
323.35

321.18(6)


Xac -
141.75
-
141.93
-
140.93(2)


Xbc
  82.43

  81.80

- 82.16(1)


 







RMS
2.95 (1.47 %)

4.81 (2.40 %)




RSD
1.58 (0.39 %)

1.58 (0.39 %)



 







Xxx -
256.82 -
256.95



Xyy -
267.72 -
267.90



Xzz
524.54

524.86




ETA
0.0208

0.0209




Øz,CBr







 
 






 








* Calculated here from experimental Xaa and Xbb - Xcc = 135.6128(3) MHz [1].

 









 









   








Table 2.  81Br nqcc's in 2-Bromobutane, G+ (MHz).  

 







Calc (1) was made on the MP2/6-311+G(3df,3pd) optimized molecular structure.

Calc (2) was made on this same structure but with empirically corrected CBr bond length.

 









Calc (1)
Calc (2)
Expt. [1]
   








Xaa
257.21

258.54

253.8573(2)


Xbb
- 72.50

- 74.63

- 71.7862 *


Xcc -
184.72
-
184.91
-
182.0711 *


Xab -
269.38
-
268.30

266.64(9)


Xac -
118.69
-
118.83
-
117.00(2)


Xbc
  68.12

  67.59

- 68.25(2)


 







RMS
2.50 (1.48 %)

4.02 (2.37 %)




RSD
1.38 (0.40 %)

1.38 (0.40 %)



 
 






 








 












Table 3.  2-Bromobutane, G+.  MP2/6-311+G(3df,3pd) structure parameters (Å and degrees).  Approximate equilibrium bond lengths are given in parentheses.
 







 C
 C,1,B1
 C,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 H,4,B4,3,A3,2,D2,0
 H,1,B5,2,A4,3,D3,0
 H,1,B6,2,A5,3,D4,0
 H,1,B7,2,A6,3,D5,0
 Br,2,B8,1,A7,3,D6,0
 H,2,B9,1,A8,3,D7,0
 H,3,B10,2,A9,1,D8,0
 H,3,B11,2,A10,1,D9,0
 H,4,B12,3,A11,2,D10,0
 H,4,B13,3,A12,2,D11,0




 B1=1.51516215   (1.5134)
 B2=1.51797573   (1.5160)
 B3=1.52080165   (1.5187)
 B4=1.08853289
 B5=1.08741528
 B6=1.08906805
 B7=1.09128492
 B8=1.95803152   (1.9616)
 B9=1.08972552
 B10=1.09431178
 B11=1.09190771
 B12=1.08784128
 B13=1.09013706
 A1=112.66252365
 A2=114.2656821
 A3=110.7318347
 A4=111.38001003
 A5=110.34717195
 A6=109.23160422
 A7=108.71726415
 A8=110.75981546
 A9=106.41671085
 A10=108.68717518
 A11=110.98932168
 A12=110.7145707
 D1=-174.57073294
 D2=176.37092333
 D3=-179.57403814
 D4=-58.95451886
 D5=60.33852906
 D6=122.33465888
 D7=-123.94556929
 D8=-53.56852365
 D9=61.34716513
 D10=-63.39638744
 D11=56.64522967

 




 








 













Table 4.  2-Bromobutane, G+.  Rotational constants (MHz), 79Br species.
 




r (1) = MP2/6-311+G(3df,3pd) opt structure.

r (2) = r (1) but with corrected C-C and CBr bond lengths.







 r (1)   r (2)     Expt. [1]






A 3894.7
3899.6
3857.83420(2)

B 2296.7
2294.1
2272.32632(2)

C 1537.3
1536.8
1520.60969(1)
   
 



 








 








[1]  S.Ka, J.Kim, H.Jang, J.J.Oh, Abstract MG03, 70th International Symposium on Molecular Spectroscopy, Champaign-Urbana, 2015.


 








 








1-Bromobutane 2-Bromopropane
g-1-Bromopropane
Ethyl Bromide


 








 








Table of Contents




Molecules/Bromine




 








 













2BrButane.html






Last Modified 19 July 2015