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CF3-CF2Br |
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Bromine |
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Nuclear
Quadrupole Coupling Constants |
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in
Perfluoroethyl Bromide
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Calculation of the bromine nqcc
tensors in perfluoroethyl bromide was made on a
molecular structure given by MP2/aug-cc-pVTZ
optimization (ropt),
and on same structure but with approximate equilibrium (~re)
CCl,
C-C, and CF bond lengths.
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Calculated nqcc tensors are compared
with experimental values [1]
in Tables 1 and 2.
Structure
parameters are given in Table 3. Rotational constants and dipole
moments (given by B1LYP/TZV(3df,3p) calculation) are given in Tables 4
and 5. Quartic centrifugal distortion constants, calculated and
experimental, are given in Table 6. |
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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.
Ø (degrees) is the angle between its subscripted
parameters. ETA = (Xxx - Xyy)/Xzz. |
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RMS is root mean square difference
between calculated and experimental diagonal nqcc's. RSD is the
calibration residual
standard deviation of
the B1LYP/TZV(3df,3p) model for calculation of the bromine nqcc's. |
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Table 1. 79Br
nqcc's in
CF3-CF2Br (MHz).
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ropt
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~re |
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Expt. [1] |
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Xaa |
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430.70 |
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433.67 |
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430.6937(53) |
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Xbb |
- |
120.37 |
- |
123.32 |
- |
121.7548(85) |
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Xcc |
- |
310.33 |
- |
310.35 |
- |
308.9389(66) |
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|Xab| |
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367.52 |
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364.98 |
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364.06(12) |
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RMS |
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1.13 (0.39 %) |
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2.10 (0.73 %) |
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RSD |
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1.58 (0.39 %) |
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1.58 (0.39 %) |
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Xxx |
- |
304.18 |
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303.92 |
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Xyy |
- |
310.33 |
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310.35 |
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Xzz |
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614.51 |
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614.27 |
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611.459(96) |
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ETA |
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0.0100 |
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0.0105 |
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Øz,a |
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26.57 |
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26.33 |
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Øa,CBr |
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28.10 |
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27.90 |
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Øz,CBr |
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1.53 |
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1.57 |
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Table 2. 81Br nqcc's in
CF3-CF2Br (MHz).
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ropt
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~re |
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Expt. [1] |
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Xaa |
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361.72 |
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364.16 |
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361.655(16) |
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Xbb |
- |
102.45 |
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104.87 |
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103.5627(25) |
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Xcc |
- |
259.27 |
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259.29 |
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258.092(19) |
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|Xab| |
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305.64 |
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303.51 |
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302.17(43) |
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RMS |
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0.94 (0.39 %) |
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1.77 (0.74 %) |
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RSD |
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1.38 (0.40 %) |
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1.38 (0.40 %) |
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Xxx |
- |
254.13 |
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253.92 |
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Xyy |
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259.27 |
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259.29 |
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Xzz |
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513.40 |
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513.20 |
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510.377(341) |
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ETA |
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0.0100 |
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0.0105 |
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Øz,a |
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26.39 |
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26.15 |
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Øa,CBr |
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27.92 |
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27.72 |
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Øz,CBr |
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1.53 |
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1.57 |
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| Table 3. CF3-CF2Br.
Selected structure
parameters (Å and degrees). Complete structures are given here in Z-matrix format. |
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| CS |
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ropt |
~re |
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C(2)Br |
1.9083 |
1.9166 |
| C(2)F(4,5) |
1.3373 |
1.3313 |
| C(2)C(3) |
1.5450 |
1.5419 |
| C(3)C(2)Br |
111.18 |
111.18 |
| C(3)C(2)F(4,5) |
108.37 |
108.37 |
| FC(2)F |
108.49 |
108.49 |
| F(4,5)C(2)Br |
110.18 |
110.18 |
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| Table 4. CF3-CF279Br
Equilibrium Rotational Constants (MHz) and Dipole Moments
(D). |
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ropt |
~re |
Expt. [1] |
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A |
2218.41 |
2233.09 |
2221.64214(26) |
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B |
1061.23 |
1061.18 |
1052.53460(14) |
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C |
962.15 |
961.96 |
954.65244(15) |
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|µa| |
0.67 |
0.61 |
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|µb| |
0.27 |
0.24 |
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| Table 5. CF3-CF281Br
Equilibrium
Rotational Constants (MHz) and Dipole Moments (D). |
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ropt |
~re |
Expt. [1] |
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A |
2217.18 |
2231.87 |
2220.3990(11) |
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B |
1050.84 |
1050.74 |
1042.20662(50) |
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C |
953.37 |
953.15 |
945.92279(52) |
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|µa| |
0.67 |
0.61 |
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|µb| |
0.27 |
0.24 |
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| Table 6. CF3-CF279Br
Quartic Centrifugal Distortion Constants (kHz). |
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B3LYP * |
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Expt [1] |
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Delta_J |
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0.0734 |
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0.0729(13) |
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Delta_KJ |
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0.0394 |
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0.0300(23) |
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Delta_K |
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0.116 |
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0.1297(76) |
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delta_J |
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0.0107 |
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0.00884(43) |
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delta_K |
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0.0114 |
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* Run B3LYP/cc-pVTZ opt
output=pickett ---> extract the principal axes structure --->
then B3LYP/cc-pVTZ freq=vibrot output=pickett. Doug Fox, Gaussian
Inc., private communication. |
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[1] B.E.Long, G.S.Grubbs
II, J.Langridge, and S.A.Cooke, J.Mol.Struct. 1023,55(2012);
B.E.Long,
J.Langridge,
S.A.Cooke, and G.S.Grubbs II, 66th International Symposium
on
Molecular Spectroscopy, Ohio State University, 2011, Abstract RH03. |
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CF3-CF2Cl |
CF3-CF2I |
CF3-CF2CN |
CH3CH2Br
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Table of Contents |
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Molecules/Bromine |
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CF3CF2Br.html |
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Last
Modified 7 Oct 2012 |
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