BrCH2CN



 









Nitrogen and Bromine


Nuclear Quadrupole Coupling Constants


in Bromoacetonitrile


 







 

 







Calculation of the N and Br nqcc tensors in bromoacetonitrile was made on a structure given by MP2/aug-cc-pVTZ optimization (1) with ~re correction for CC and CN bond lengths, and (2) with ~re correction for CC, CN, and CBr bond length, and on the partial ro strcuture of Gum and Graybeal [1].  These are compared with the experimental nqcc's of Xu et al. [2] in Tables 1 - 4.  Structure parameters are given in Table 5, rotational constants in Table 6.
 
In Tables 1 - 4, 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 c-axis.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
RMS is the root measn square difference between calculated and experimental diagonal nqcc's (percent of the average of the absolute experimental nqcc's).  RSD is the residual standard deviation of the calibration of the computional model for calculation of the nqcc's.
 
 
   






Table 1.  14N nqcc's in 79BrCH2C14N (MHz).  Calculation was made on MP2/aug-cc-pVTZ optimized structure (1) with ~re correction for CC and CN bond length and (2) with ~re correction for CC, CN, and CBr bond length.
   







Calc (1)
Calc (2)
Expt. [2]
   





Xaa - 2.225 - 2.216 - 2.20007(26)
Xbb 0.227 0.224 0.18407
Xcc 1.998 1.992 2.01600
|Xab| 3.094 3.101 3.0821(23)
 
RMS 0.030 (2.1 %) 0.029 (2.0 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 2.329 2.336 2.2966(22)
Xyy 1.998 1.992 2.0160(3)
Xzz - 4.327 - 4.328 - 4.3126(22)
ETA - 0.076 - 0.080
Øz,a 34.19 34.26 34.427(7)
Øa,CN 34.22 34.33
Øz,CN   0.03   0.07
 
 
 
   






Table 2.  79Br nqcc's in 79BrCH2C14N (MHz).  Calculation was made on MP2/aug-cc-pVTZ optimized structure (1) with ~re correction for CC and CN bond length and (2) with ~re correction for CC, CN, and CBr bond length.
   







Calc (1)
Calc (2)
Expt. [2]
   





Xaa 353.90 356.72 350.46246(24)
Xbb - 33.01 - 34.61 - 29.85428
Xcc - 320.90 - 322.11 - 320.60818
|Xab| 434.19 435.27 435.2430(15)
 
RMS 2.70 (1.16 %) 4.62 (1.98 %)
RSD 1.58 (0.39 %) 1.58 (0.39 %)
 
Xxx - 314.88 - 316.18 - 314.6661(14)
Xyy - 320.90 - 322.11 - 320.6082(3)
Xzz 635.78 638.28 635.2743(14)
ETA 0.0094 0.0093
Øz,a 32.99 32.90 33.1997(1)
Øa,CBr 33.83 33.73
Øz,CBr   0.84   0.83
 
 
 
   






Table 3.  Nitrogen and Bromine nqcc's in 81BrCH2C14N (MHz).  Calculation was made on MP2/aug-cc-pVTZ optimized structure (1) with ~re correction for CC and CN bond length and (2) with ~re correction for CC, CN, and CBr bond length.
   







Calc (1)
Calc (2)
Expt. [2]
   





Xaa(14N) - 2.219 - 2.210 - 2.19492(33)
Xbb 0.221 0.218 0.18465
Xcc 1.998 1.992 2.01027
|Xab| 3.096 3.103 3.0779(20)
 
RMS 0.026 (1.8 %) 0.024 (1.6 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xaa(81Br) 296.38 298.73 293.47337(30)
Xbb - 28.28 - 29.62 - 25.643905
Xcc - 268.10 - 269.11 - 267.829465
|Xab| 362.44 363.34 363.29884(94)
 
RMS 2.26 (1.16 %) 3.88 (1.98 %)
RSD 1.38 (0.40 %) 1.38 (0.40 %)
 
 
 

   






Table 4.  Nitrogen and Bromine nqcc's in 79BrCH2C14N (MHz).  Calculation was made on the partial ro structure [1].
   









Calc.
Expt. [2]
   





14N Xaa - 2.267 - 2.20007(26)
Xbb 0.416 0.18407
Xcc 1.852 2.01600
|Xab| 3.030 3.0821(23)
 
RMS 0.168 (11.5 %)
RSD 0.030 (1.3 %)
 
79Br Xaa 331.9 350.46246(24)
Xbb   - 4.4 - 29.85428
Xcc - 327.5 - 320.60818
|Xab| 462.0 435.2430(15)
   
RMS 18.6 (7.8 %)
RSD 1.58 (0.39 %)
 


 







 
 
Table 5.  Bromoacetonitrile.  Molecular structure parameters,  MP2/aug-cc-pVTZ optimized structure (1) with ~re correction for CC and CN bond length and (2) with ~re correction for CC, CN, and CBr bond length: and ro [1] (Å and degrees).  * Assumed value.  Note: ~re (2) = ~re (1) but with CBr = 1.9382 Å.
 
~re (1)   ro [1]
CBr 1.9301 1.901(20)
CC 1.4523 1.487(20)
CN 1.1563 1.158 *
CH 1.0854 1.107(20)
H···H 1.7796 1.718 *
CCBr 110.83 111.53(150)
CCH 107.37 102.87(150)
CCN 178.88 ** 180 *
 
** CN tilts away from Br.


 
 
Table 6.  Bromoacetonitrile.  Rotational Constants (MHz).  79Br species.
 
~re (1) ~re (2)   Expt. [2]
A 22126.25 22049.6 21967.51427(13)
B   2212.64   2203.3   2196.945000(30)
C   2037.37   2028.8   2020.904820(36)
 
 
[1] M.L.Gum and J.D.Graybeal, J.Mol.Spectrosc. 62,364(1976).
[2] Y.Xu, W.Jäger, M.C.L.Gerry, and I.Merke, J.Mol.Spectrosc. 160,258(1993).

 








 








CH3Br CH3CN CHF2Br

CF2BrCl ClCH2CN CH2BrCl
 

 








Table of Contents



Molecules/Nitrogen

Molecules/Bromine



 

 













BrCH2CN.html






Last Modified 19 July 2009