CHBrClF




 





 
 


Chlorine and Bromine


Nuclear Quadrupole Coupling Constants

in Bromochlorofluoromethane

 







 
 
The complete nqcc tensors for chlorine and bromine in bromochlorofluoromethane have been determined by Bauder et al. [1].  Calculation was made here of the 35Cl and 79Br nqcc tensors in CH79Br35ClF on the molecular structure given by MP2/aug-cc-pVTZ, and on this same structure but with CH, CCl, and CBr bond lengths corrected as discussed below.  Calculated and experimental nqcc tensors are compared in Tables 1 and 4.  Eigenvalues and eigenvectors of the tensors are shown in Tables 2,3,5, and 6.  Structure parameters are given in Table 7, atomic coordinates in Table 8, and rotational constants in Table 9.
 
In Tables 1 and 4, 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 algebraic signs of the off-diagonal elements of the inertia axes nqcc's are consistent with the atomic coordinates given in Table 8.)  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 of the model for calculation of the chlorine nqcc's.
 
 
   






Table 1.  35Cl nqcc's in CH79BrClF (MHz).  Calculation was made (1) on the MP2/aug-cc-pVTZ optimized structure, and (2) on this same structure but with corrected CCl, CF, and CH bond lengths.
   







Calc. (1)
Calc. (2)
Expt. [1]
   





Xaa - 21.26 - 21.10 - 20.5952(73)
Xbb - 8.36 - 8.37 - 8.5459(46)
Xcc 29.62 29.47 29.1411(43)
Xab - 51.86 - 51.65 - 51.27(16)
Xac 23.57 23.50 23.86(28)
Xbc 19.32 19.31 19.36(37)
 
RMS 0.48 (2.5 %) 0.36 (1.9 %)
RSD 0.49 (1.1 %) 0.49 (1.1 %)
 
Xxx 39.12 38.95 39.06
Xyy 36.75 36.62 36.17
Xzz - 75.87 - 75.57 - 75.22
ETA - 0.0311 - 0.0308 - 0.0384
Øz,CCl 1.40 1.45
 

 
 
 
Table 2.  35Cl in CH79BrClF.  Eigenvalues; Xii, i=x,y,z (MHz) and eigenvectors (direction cosines) of the nqcc tensor.  MP2/aug-cc-pVTZ optimized structure.
 
  i =    x    y    z
 
Xii 39.12 36.75 - 75.87
 
a 0.5345 - 0.4396 0.7219
b - 0.2561 0.7297 0.6340
c 0.8054 0.5238 - 0.2774
 
 
 
 
Table 3.  35Cl in CH79BrClF.  Eigenvalues; Xii, i=x,y,z (MHz) and eigenvectors (direction cosines) of the nqcc tensor.  MP2/aug-cc-pVTZ optimized structure with corrected CCl, CF, and CH bond lengths.
 
  i =    x    y    z
 
Xii 38.95 36.62 - 75.57
 
a 0.5325 - 0.4428 0.7214
b - 0.2514 0.7310 0.6343
c 0.8082 0.5191 - 0.2780
 
 
 
   






Table 4.  79Br nqcc's in CHBr35ClF (MHz).  Calculation was made (1) on the MP2/aug-cc-pVTZ optimized structure, and (2) on this same structure but with corrected CCl, CF, and CH bond lengths.
   







Calc. (1)
Calc. (2)
Expt. [1]
   





Xaa 457.19 456.80 456.0650(57)
Xbb - 211.27 - 211.67 - 212.1230(41)
Xcc - 245.92 - 245.13 - 243.9420(34)
Xab - 250.76 - 249.43 - 249.301(64)
Xac 196.25 196.19 199.66(12)
Xbc - 58.05 - 57.71 - 59.14(25)
 
RMS 1.40 (0.46 %) 0.85 (0.28 %)
RSD 1.58 (0.39 %) 1.58 (0.39 %)
 
Xxx - 302.22 - 301.68 - 301.96
Xyy - 288.58 - 287.98 - 288.77
Xzz 590.80 589.65 590.73
ETA - 0.0231 - 0.0232 - 0.0223
Øz,CCl 1.01 1.00
 
 
 
 
Table 5.  79Br in CHBr35ClF.  Eigenvalues; Xii, i=x,y,z (MHz) and eigenvectors (direction cosines) of the nqcc tensor.  MP2/aug-cc-pVTZ optimized structure.
 
  i =    x    y    z
 
Xii - 302.22 - 288.58 590.80
 
a - 0.3791 0.0776 0.9221
b - 0.5901 0.7473 - 0.3055
c 0.7128 0.6600 0.2375
 
 
 
Table 6.  79Br in CHBr35ClF.  Eigenvalues; Xii, i=x,y,z (MHz) and eigenvectors (direction cosines) of the nqcc tensor.  MP2/aug-cc-pVTZ optimized structure with corrected CCl, CF, and CH bond lengths.
 
  i =    x    y    z
 
Xii - 301.68 - 287.98 589.65
 
a - 0.3795 0.0714 0.9224
b - 0.6002 0.7397 - 0.3042
c 0.7040 0.6691 0.2378
 
 
 
Molecular Structure
 
Calculation was made (1) on the MP2/aug-cc-pVTZ  optimized structure, and (2) on this same structure but with corrected CCl, CF, and CH bond lengths. 
The CCl bond length calculated by MP2/6-311+G(2d,p) optimization was corrected by linear regression analysis of the data in Table 4 of Ref. [2].  For the CF bond, the structure was optimized at the MP2/6-311+G(d,p) level, and corrected by linear regression analysis of the data in Table 6 of Ref. [3].  The CH bond lengths were corrected using r = 1.001 ropt, where ropt is obtained by MP2/6-31G(d,p) optimization [4].
 
 
Table 7.  Bromochlorofluoromethane.  Structure parameters (Å and degrees).   (1) MP2/aug-cc-pVTZ  optimized structure, and (2) MP2/aug-cc-pVTZ optimized structure with corrected CCl, CF, and CH bond lengths.
 
Struct. (1) Struct. (2)
Z-Matrix CH 1.0832 1.0853
CF 1.3511 1.3475
CCl 1.7568 1.7514
CBr 1.9177
HCF 109.60
HCCl 108.90
HCBr 107.97
FCCl 109.44
FCBr 109.29
ClCBr 111.62

 
 
Table 8.  CH79Br35ClF.  Atomic coordinates.  (1) MP2/aug-cc-pVTZ  optimized structure, and (2) MP2/aug-cc-pVTZ optimized structure with corrected CCl, CF, and CH bond lengths.
(More figures are shown than are significant.)
 
  a (Å)   b (Å)   c (Å)
(1) Cl 1.862086
 0.691537
 - 0.057584
C 0.623782
 - 0.451937
 0.437709
Br - 1.132639
 0.165291
 - 0.022386
F 0.848234
 - 1.643784
 - 0.157787
H 0.665322
 - 0.569804
 1.513678



(2) Cl 1.858230
 0.691234
 - 0.057546
C 0.625685
 - 0.450696
 0.436652
Br - 1.131912
 0.164046
 - 0.022280
F 0.850958 - 1.638878 - 0.157681
H 0.668099 - 0.569001 1.514651
 
 
Table 9.  CH79Br35ClF.  Rotational constants (MHz).  Calc. (1) MP2/aug-cc-pVTZ  optimized structure, and Calc. (2) MP2/aug-cc-pVTZ  optimized structure with corrected CCl, CF, and CH bond lengths.
 
Calc. (1) Calc. (2)     Expt. [1]
A 6460.3 6491.6 6466.869 61(53)
B 2050.1 2054.4 2038.541 46(15)
C 1608.1 1612.6 1600.800 03(19)
 
 
[1] A.Bauder, A.Beil, D.Luckhaus, F.Müller, M.Quack, J.Chem.Phys. 106,7558(1997).
[2] I.Merke, L.Poteau, G.Wlodarczak, A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996).
[3] R.M.Villamañan, W.D.Chen, G.Wlodarczak, J.Demaison, A.G.Lesarri, J.C.López, and J.L.Alonso, J.Mol.Spectrosc. 171,223(1995).

[4] J.Demaison and G.Wlodarczak, Structural Chem. 5,57(1994).

 







"High precision rovibrational and hyperfine analysis of the nu4 = 1 level of bromochlorofluoromethane"  T.Marrel, M.Ziskind, C.Daussy, and C.Chardonnet, J.Mol.Struct. 599,195(2001).
 
 
CH3Cl CH3CH2Cl CH3Br CH3CH2Br
CF3Cl CF3Br CH2BrCl CF2BrCl
 

 








Table of Contents




Molecules/Chlorine



Molecules/Bromine
 

 













CHBrClF.html






Last Modified 15 Dec 2005