ClCH2CH2CH2CH3


 




 
 


Chlorine


Nuclear Quadrupole Coupling Constants

in 1-Chloro-n-Butane GT

 







 
 
Calculation of the chlorine nqcc's in 1-chloro-n-butane GT was made on approximate equilibrium structures given by MP2 optimization in conjunction with Pople-type bases, with empirical correction for the CH, C-C, and CCl bond lengths (~ re).  These are compared with the experimental nqcc's of Melandri et al. [1] in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants in Table 4.
 
In Tables 1 - 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.  Øz,CCl (degrees) is the angle between the principal z-axis of the nqcc tensor and the CCl bond axis.  ETA = (Xxx - Xyy)/Xzz.
RMS is the root mean square difference between calculated and experimental diagonal nqcc's.  RSD is the calibration residual standard deviation of the B1LYP/TZV(3df,2p) model for calculation of the chlorine nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's.
 
 
 
   




Table 1.  35Cl nqcc's in 1-chloro-n-butane GT (MHz).  Calculation was made on the ~ re structure, with interatomic angles given by (1) MP2/6-311+G(d,p) and (2) MP2/6-311+G(2d,p) optimizations.
   




Calc/~ re(1) Calc/~ re(2) Expt. [1]
   



Xaa   1.05   0.68   1.06(52)
Xbb - 33.00 - 32.64 - 33.06(27)
Xcc 31.95 31.95 32.00
|Xab|* 48.38 48.36
|Xac|* 10.50 10.35
|Xbc|* 15.88 15.66
 
RMS 0.04 (0.20 %) 0.33 (1.5 %)
RSD 0.49 (1.1 %) 0.49 (1.1 %)
 
Xxx 34.79 34.62
Xyy 36.00 35.94
Xzz - 70.79 - 70.56
ETA 0.017 0.019
Øz,CCl   0.87   0.69
 

 
* The product XabXacXbc is negative.
 
 
   




Table 2.  37Cl nqcc's in 1-chloro-n-butane GT (MHz).  Calculation was made on the ~ re structure, with interatomic angles given by (1) MP2/6-311+G(d,p) and (2) MP2/6-311+G(2d,p) optimizations.
   




Calc/~ re(1) Calc/~ re(2) Expt. [1]
   



Xaa   0.34   0.04   0.78(41)
Xbb - 25.58 - 25.29 - 25.50(84)
Xcc 25.24 25.25 24.72
|Xab|* 38.32 38.31
|Xac|*   8.25   8.14
|Xbc|* 12.33 12.16
 
RMS 0.40 (2.4 %) 0.54 (3.2 %)
RSD 0.44 (1.1 %) 0.44 (1.1 %)
 
 
* The product XabXacXbc is negative.
 
 
Table 3. 1-Chloro-n-Butane GT.  Heavy atom structure parameters, ~ re(1) and ~ re(2) (Å and degrees).   Complete structures are given here in Z-matrix format.
~ re(1) is ~ re bond lengths with MP2/6-311+G(d,p) interatomic angles,  ~ re(2) is ~ re bond lengths with MP2/6-311+G(2d,p) angles.
 
~ re(1) ~ re(2)
 

ClC(1) 1.7892 1.7892
C(1)C(2) 1.5123 1.5123
C(2)C(5) 1.5193 1.5193
C(5)C(8) 1.5204 1.5204
ClC(1)C(2) 111.60 111.84
C(1)C(2)C(5) 113.98 114.08
C(2)C(5)C(8) 112.28 111.94
C(5)C(2)C(1)Cl   - 66.44   - 65.41
Click on image to enlarge. C(1)C(2)C(5)C(8) - 178.10 - 177.82

 
 
Table 4.  Rotational Constants (MHz).  35Cl Species.
~ re(1) ~ re(2)  Expt. [1]
A  9552.9  9482.4 9419.557(8)
B  1710.7  1675.5 1696.465(1)
C  1556.3  1525.4 1541.281(1)
 

 
Substitution coordinates of the Cl atom were determined [1]:  These are (| a |, | b |, | c |) = (1.7823, 0.4527, 0.1134 Å).  On the ~ re(1) structure, (| a |, | b |, | c |) = (1.7788, 0.4491, 0.0688 Å); and on the  ~ re(2) structure, = (1.7787, 0.4483, 0.0697 Å).
 
 

[1]  S.Melandri, P.G.Favero, D.Damiani, W.Caminati, and L.B.Favero, J.Chem.Soc. Faraday Trans. 90,2183(1994).
 
 
1-Chloro-n-Butane TT 1-Chloro-n-Butane TG
1-Chloro-n-Butane GG 1-Chloro-n-Butane GG'
 

 








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Last Modified 13 Jan 2008