HCC-CH2Br




































 









Bromine


Nuclear Quadrupole Coupling Constants


in Propargyl Bromide


 








 


 





Bromine nqcc's in propargyl bromide were determined by Duffy et al. [1].

 








Calculation of the nqcc's was made here on molecular structures derived by MP2/aug-cc-pVTZ(G03) optimization (ropt), and on this optimized structure but with corrected CBr, C-C, and triple CC bond lengths (~ resee here).  These 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.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular symmetry plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

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

 








  








   








Table 1.  79Br nqcc's in HCC-CH2Br (MHz).  Calculation was made on (1) the ropt structure, and (2) the ~ re structure.

 









Calc (1)
Calc (2)
Expt. [1]
   








Xaa
320.50
323.26
320.82(90)

Xbb
- 19.29
- 21.35
- 19.78

Xcc - 301.21 - 301.90 - 301.04(45)

|Xab|
415.25
415.54
415.95(32)

 







RMS
0.35 (0.16 %)
1.75 (0.82 %)



RSD
1.58 (0.39 %)
1.58 (0.39 %)



 







Xxx - 298.06  - 298.90 - 298.95(42)

Xyy - 301.21 - 301.90 - 301.04(45)

Xzz
599.27
600.80
599.99(42)

ETA
0.0052
0.0050
0.003

Øz,a
33.87
33.74
33.87

Øa,CBr
34.27
34.12



Øz,CBr
  0.40
  0.38



 







   








 








   








Table 2.  81Br nqcc's in HCC-CH2Br (MHz).  Calculation was made on (1) the ropt structure, and (2) the ~ re structure.

 









Calc (1)
Calc (2)
Expt. [1]
   








Xaa
268.47
270.77
269.45(95)

Xbb
- 16.82
- 18.54
- 17.68

Xcc - 251.65 - 252.23 - 251.77(48)

|Xab|
346.64
346.88
346.52(65)

 







RMS
0.75 (0.42 %)
0.95 (0.53 %)



RSD
1.38 (0.40 %)
1.38 (0.40 %)



 








 








 












Table 3.  HCC-CH2Br.  Molecular structure parameters, ropt and ~ re (Å and degrees).   These structures are given here in Z-matrix format.
 


Click on
  ropt  ~ re
image to enlarge.



BrC(2) 1.9425 1.9505
C(2)H(6,7) 1.0860 1.0860
C(2)C(3) 1.4458 1.4471
C(3)C(4) 1.2151 1.2043
C(4)H 1.0618 1.0618
BrC(2)C(3) 111.30 111.30
CCCH Angles are C(2)C(3)C(4) 179.44 179.44
exaggerated C(3)C(4)H 179.83 179.83

C(3)C(2)H(6,7) 111.65 111.65

H(6)C(2)H(7) 109.78 109.78


 








 













Table 4.  HCC-CH2Br.  Rotational constants (MHz).  79Br species.
 



 
   ropt   ~ re    Expt. [1]






A 21 022.4 21 008.7 21 010.306(12)

B   2 184.1   2 178.6   2 169.3287(10)

C   2 003.5   1 998.8   1 989.0591(11)


 








 








[1] P.K.J.Duffy, C.Hwang, D.T.Cramb, W.Lewis-Bevan, and M.C.L.Gerry, J.Mol.Spectrosc. 127,549(1988).











Y.Kikuchi, E.Hirota, and Y.Morino, Bull.Chem.Soc.Jpn. 34,348(1961):  Xaa = 316, Xbb =  -16, and Xab = 403 MHz.


 








 








HCC-CH2Cl HCC-CH2I HCC-CH2CN CH3Br

 








 








Table of Contents




Molecules/Bromine




 








 













HCCCH2Br.html






Last Modified 2 March 2008