CHF2Br PDF

 

 







Bromine


Nuclear Quadrupole Coupling Constants


in Bromodifluoromethane


 







 
 
Bromine nqcc's in bromodifluoromethane were determined by Ogata et al. [1], who also derived an effective ro molecular structure.   Calculation of the nqcc's was made here on this structure, on an ~re structure given by MP2/aug-cc-pVTZ optimization with empirically corrected CBr, CCl, and CF bond lengths, and on an ab initio (a.i.) re structure derived by Charmet et al. [2] by CCSD(T) method in conjunction with a hierarchical series of correlation consistent bases extrapolated to CBS.  Calculated and experimental nqcc's are compared in Tables 1 and 2.  Structure parameters are given in Table 5.
 
In Tables 3 and 4, the results are shown of calculation on a CCSD(T)/cc-pCVQZ ab initio structure derived by Cazzoli et al. [3].  Also shown in these Tables are the results of calculation of the nqcc's made at the CCSD(T)/cc-pCVQZ level of theory with relativistic and vibrational corrections [3].  These are compared with the experimental nqcc's of Cazzoli et al. [3].

 


 




In Tables 1 - 4, the subscripts a,b,c refer to the principal axes of the inertia tensor. Subscripts x,y,z refer to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the b-axis.  These are perpendicular to the symmetry plane of the molecule.  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 (percentage of average of absolute experimental nqcc's).  RSD is the residual standard deviation of the calibration of the computional model for calculation of the nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's.

 







 

   







Table 1.  79Br nqcc's in CHF2Br (MHz).   Calculation was made on ro, ~re, and a.i. re [2] structures.
   








Calc / ro
Calc / ~re Calc / a.i. re
Expt. [1]
   






Xaa 530.28 523.75 524.54 521.28(9)
Xbb - 282.62 - 280.32 - 280.78 - 279.80(6)
Xcc - 247.66 - 243.43 - 243.76 - 241.48
|Xac| 183.87 183.02 182.77 187.1(26)
 
RMS 6.58 (1.9 %) 1.84 (0.53 %) 2.37 (0.68 %)
RSD 1.58 (0.39 %) 1.58 (0.39 %) 1.58 (0.39 %)
 
Xxx - 288.93 - 284.86 - 285.02 - 284.9(23)
Xyy - 282.62 - 280.32 - 280.78 - 279.80(6)
Xzz 571.55 565.18 565.80 564.7(23)
ETA - 0.011 - 0.0080 - 0.0075 - 0.009(4)
Øz,a 12.6 12.75 12.72 13.1(3)
Øa,CBr 12.5 12.48 12.46
Øz,CBr   0.1   0.27   0.26
 

 
 
 
   







Table 2.  81Br nqcc's in CHF2Br (MHz).  Calculation was made on ro, ~re, and a.i. re [2] structures.
   








Calc / ro
Calc / ~re Calc / a.i. re
Expt. [1]
   






Xaa 443.09 437.64 438.30 435.61(10)
Xbb - 236.12 - 234.20 - 234.58 - 233.84(6)
Xcc - 206.97 - 203.44 - 203.71 - 201.76
|Xac| 153.49 152.79 152.57 148.5(29)
 
RMS 5.42 (1.9 %) 1.53 (0.53 %) 1.96 (0.68 %)
RSD 1.38 (0.40 %) 1.38 (0.40 %) 1.38 (0.40 %)
 
Xxx - 241.39 - 237.99 - 238.13 - 234.6(25)
Xyy - 236.12 - 234.20 - 234.58 - 233.84(6)
Xzz 477.51 472.19 472.71 468.5(25)
ETA - 0.011 - 0.0080 - 0.0075 - 0.002(5)
Øz,a 12.6 12.74 12.71 12.5(4)
Øa,CBr 12.5 12.47 12.45
Øz,CBr   0.1   0.27   0.26
 

 
 
   







Table 3.  79Br nqcc's in CHF2Br (MHz).   Calculation was made on the a.i. re [3] structure.
   










Calc Calc [3]
Expt. [3]
   






79Br Xaa 522.94 521.353 521.257(9)
Xbb - 279.68 - 279.659 - 279.804(40)
Xcc - 243.27 - 241.694 - 241.453(40)
|Xac| 181.57 183.963 185.87(28)
 
RMS 1.43 (0.41 %) 0.172 (0.05 %)
RSD 1.58 (0.39 %)
 
Xxx - 284.11
Xyy - 279.68
Xzz 563.79
ETA - 0.0079
Øz,a 12.68
Øa,CBr 12.45
Øz,CBr   0.23
 
 
 
   







Table 4.  81Br nqcc's in CHF2Br (MHz).   Calculation was made on the a.i. re [3] structure.
   










Calc Calc [3]
Expt. [3]
   






81Br Xaa 436.96 435.628 435.521(10)
Xbb - 233.66 - 233.644 - 233.701(32)
Xcc - 203.30 - 201.984 - 201.820(32)
|Xac| 151.57 153.567 155.210(89)
 
RMS 1.19 (0.41 %) 0.118 (0.04 %)
RSD 1.58 (0.39 %)
 
Xxx - 237.37
Xyy - 233.66
Xzz 471.03
ETA - 0.0079
Øz,a 12.67
Øa,CBr 12.44
Øz,CBr   0.23
 
 
 
Table 5.   CHF2Br  Structure parameters, ro [2],  ~re, and a.i. re [2,3] (Å and degrees).
 
    ro   ~re  a.i. re [2]  a.i. re [3]
CBr 1.908(15) 1.9258 1.9355 1.9275
CF 1.347(11) 1.3359 1.3358 1.3343
CH 1.098 1.0849 1.0854 1.0842
BrCH 110.8 109.02 108.44 108.60
BrCF 110.6(8) 109.77 109.55 109.71
FCF 107.4(1) 108.22 108.45
HCF 110.21
Z-Matrix
H
C 1 R2
Br 2 R3 1 A3
F 2 R4 3 A4 1   D
F 2 R4 3 A4 1 - D
 
            ro   ~re  a.i. re [2]  a.i. re [3]
R2 = 1.098 1.0849 1.0854 1.0842
R3 = 1.908 1.9258 1.9355 1.9275
R4 = 1.347 1.3359 1.3358 1.3343
A3 = 110.8 109.024 108.44 108.60
A4 = 110.6 109.7735 109.55 109.71
D = 120.5735 120.4292 120.5765 120.51401
 
 
[1] T.Ogata, S.Kuwano, and S.Oe, J.Mol.Spectrosc. 185,147(1997).
[2] A.P.Charmet, P.Stoppa, N.Tasinato, A.Baldan, S.Giorgianni, and A.Gambi, J.Chem.Phys. 133,044310(2010).
[3] G.Cazzoli, L.Cludi, C.Puzzarini, P.Stoppa, A.Pietropolloi Charmet, N.Tasinato, A.Baldacci, A.Baldan, S.Giorgianni, R.Wugt Larsen, S.Stopkowicz, and J.Gauss, J.Physical Chemistry A, 115,453(2011).
 

 








BrClCF2 CH3Cl CH3Br CF2Cl2

CHF2Cl CF3Cl CF3Br CH2Cl2
CH2FCl CH2Br2 BrClCH2
 

 








Table of Contents




Molecules/Bromine



 

 













CHBrF2.html






Last Modified 27 Dec 2010