OC2H3-CH2Br













 








Bromine

Nuclear Quadrupole Coupling Constants

in (Bromomethyl)oxirane

 








 








Calculation of the bromine nqcc tensors in (bromomethyl)oxirane (BMO) was made on MP2/6-311+G(d,p) and MP2/6-311+G(2d,2p) optimized structures of each gauche conformer shown below:

 








BMO gauche I

BMO gauche II































 








At MP2/6-311+G(d,p) and MP2/6-311+G(2d,2p) levels of theory respectively, EII < EI by 2.8/3.3 kJ/mol.  A third conformer, cis, is 8.6/8.0 kJ/mol higher than EII.











Calculated nqcc tensors are shown in Tables 1 and 2, structure parameters in Table 3, rotational constants and dipole moments in Table 4, quartic centrifugal distortion constants in Table 5.

 








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 principal z-axis of the nqcc tensor and the CBr bond axis.

RSD is the calibration residual standard deviation of the B1LYP/TZV(3df,3p) model for calculation of the efg's/nqcc's.

 








 








 








Table 1.  Bromine nqcc's in BMO, gauche I (MHz).  Calculation was made on (1) MP2/6-311+G(d,p) and (2) MP2/6-311+G(2d,2p) optimized structures.
 










Calc (1)
Calc (2)
Expt
 








Xaa (79Br)
338.87
345.72



Xbb
- 60.42
- 76.71



Xcc -
 270.45
 -
 269.01



Xab
373.28
367.72



Xac
- 81.41
- 84.79



Xbc
- 55.67
- 56.49



 







RSD
1.58 (0.39 %)
1.58 (0.39 %)












Xxx -
 293.42
 -
 293.02



Xyy -
 278.52
 -
 277.86



Xzz
571.94
570.88



ETA -
 0.0260
 -
 0.0266



Øz,CBr
0.20
0.16












Xaa (81Br)
283.50
289.21



Xbb
- 57.54
- 64.45



Xcc -
 225.96
 -
 224.76



Xab
311.66
307.01



Xac
- 68.02
- 70.84



Xbc
- 46.46
- 47.13












RSD
1.38 (0.40 %)
1.38 (0.40 %)













 








 








 








Table 2.  Bromine nqcc's in BMO, gauche II (MHz).  Calculation was made on (1) MP2/6-311+G(d,p) and (2) MP2/6-311+G(2d,2p) optimized structures.
 










Calc (1)
Calc (2)
Expt
 








Xaa (79Br)
364.96
368.64



Xbb -
 100.09
 -
 103.97



Xcc -
 264.87
 -
 264.67



Xab
345.83
342.10



Xac
105.21
103.94



Xbc
  62.10
  60.76



 







RSD
1.58 (0.39 %)
1.58 (0.39 %)












Xxx -
 288.88 -
 288.27



Xyy -
 270.19 -
 277.26



Xzz
567.07
565.53



ETA -
 0.0188
 -
 0.0194



Øz,CBr
0.21
0.18












Xaa (81Br)
305.27
308.33



Xbb
- 83.95
- 87.18



Xcc -
 221.32
 -
 221.14



Xab
288.71
285.59



Xac
  87.86
  86.80



Xbc
  51.79
  50.68












RSD
1.38 (0.40 %)
1.38 (0.40 %)













 








 


Table 3.  Heavy atom structure parameters, ropt(1) = MP2/6-311+G(d,p) and ropt(2) = MP2/6-311+G(2d,2p) (Å and degrees).  Complete molecular structure parameters are given here in Z-matrix format.
 


BMO gauche I
ropt(1) ropt(2)
 



C(1)C(2) 1.47161.4687
C(2)O 1.42991.4370
OC(1) 1.43761.4454
C(2)C(7) 1.49631.4896
C(7)Br 1.94791.9507
OC(2)C(1)   59.38  59.65
C(2)C(1)O   58.87  59.08
C(1)OC(2)   61.75  61.27
C(1)C(2)C(7) 120.19119.78
C(2)C(7)Br 110.73110.99
C(1)C(2)C(7)Br 147.39148.52
 


 


BMO gauche II
ropt(1) ropt(2)
 


C(1)C(2) 1.46521.4616
C(2)O 1.43621.4431
OC(1) 1.44221.4510
C(2)C(7) 1.49981.4928
C(7)Br 1.94731.9502
OC(2)C(1)   59.61  59.93
C(2)C(1)O   59.20  59.40
C(1)OC(2)   61.20  60.66
C(1)C(2)C(7) 120.54120.15
C(2)C(7)Br 109.71109.76
C(1)C(2)C(7)Br - 92.96
- 93.03


 








 














Table 4. (Bromomethyl)oxirane, 79Br species.  Rotational constants (MHz) and Dipole Moments * (D).  ropt(1) = MP2/6-311+G(d,p) and ropt(2) = MP2/6-311+G(2d,2p)









 ropt(1)  ropt(2)   Expt [1]







gauche I A 12654.3
 12710.1
 12296.050


B   1395.9
   1392.2
   1391.677


C   1319.9
   1317.3
   1317.360

  |µa|
   1.86
   1.88


|µb|   2.58
   2.62


|µc|   0.39
   0.40







gauche II A
 12614.6
 12656.2
 12278.436


B
   1345.4
   1347.6
   1378.830


C
   1276.8
   1279.0
   1304.852


|µa|   0.20
   0.18


|µb|   0.47
   0.50


|µc|   0.09
   0.08







* B1LYP/TZV(3df,3p) calculation of dipole moments on ropt strcutures.


 








 

















Table 5.  (Bromomethyl)oxirane, 79Br species.  Quartic Centrifugal Distortion Constants (kHz).  Calc = B3LYP/cc-pVTZ










Calc gauche I   Expt
 Calc gauche II   Expt









Delta_J
0.392


0.299

Delta_JK -
 5.74

-
 4.93

Delta_K
61.7


66.9

delta_J
0.0391


0.0341

delta_K
1.47


1.75

D_J
0.389


0.297

D_JK -
 5.73

-
 4.91

D_K
61.7


66.9

d_1
 -
 0.0391

-
 0.0341

d_2
 -
 0.00110

-
 0.00126




 








 








[1] M.A.Mohammdi and W.V.F.Brooks, J.Mol.Spectrosc. 77,85(1979).

 








 








(Chloromethyl)oxirane



 








 








Table of Contents




Molecules/Bromine




 








 













BrMeOxirane.html






Last Modified 4 Jan 2014