ClCH2CH2CH2CH3


 




 
 


Chlorine


Nuclear Quadrupole Coupling Constants

in 1-Chloro-n-Butane GG

 







 
 
Calculation of the chlorine nqcc's in 1-chloro-n-butane GG 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 GG (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 - 4.83 - 5.54 - 6.5(4)
Xbb - 6.87 - 6.72 - 6.1(2)
Xcc 11.70 12.26 12.6
|Xab|* 41.29 41.52
|Xac|* 30.50 30.18
|Xbc|* 31.21 30.70
 
RMS 1.2 (14 %) 0.7 (8.2 %)
RSD 0.49 (1.1 %) 0.49 (1.1 %)
 
Xxx 34.91 34.74
Xyy 35.46 35.40
Xzz - 70.36 - 70.15
ETA 0.008 0.010
Øz,CCl   0.66   0.48
 

 
* The product XabXacXbc is negative.
 
 
   




Table 2.  37Cl nqcc's in 1-chloro-n-butane GG (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.
   



Xaa - 4.43 - 4.99
Xbb - 5.09 - 4.97
Xcc   9.53   9.96
|Xab|* 32.70 32.88
|Xac|* 24.07 23.81
|Xbc|* 24.27 23.87
 
RSD 0.44 (1.1 %) 0.44 (1.1 %)
 
 
* The product XabXacXbc is negative.
 
 
Table 3. 1-Chloro-n-Butane GG.  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) 1.5129 1.5129
C(2)C(3) 1.5226 1.5226
C(3)C(4) 1.5218 1.5218
ClC(1)C(2) 111.41 111.83
C(1)C(2)C(3) 114.63 114.82
C(2)C(3)C(4) 113.41 113.46
C(3)C(2)C(1)Cl - 59.83 - 59.71
Click on image to enlarge. C(1)C(2)C(3)C(4) - 55.45 - 56.17

 
 
Table 4.  Rotational Constants (MHz).  35Cl Species.
~ re(1) ~ re(2)  Expt. [1]
A 6635.7 6667.4 6804.03(1)
B 2201.5 2183.0 2093.497(3)
C 1985.7 1971.7 1911.382(3)
 

 
Substitution coordinates of the Cl atom were determined [1]:  These are (| a |, | b |, | c |) = (1.635, 0.405, 0.124 Å).  On the ~ re(1) structure, (| a |, | b |, | c |) = (1.597, 0.404, 0.132 Å); and on the  ~ re(2) structure, = (1.605, 0.404, 0.131 Å).
 
 

[1]  S.Melandri, P.G.Favero, W.Caminati, L.B.Favero, and A. Delgi Esposti, J.Chem.Soc. Faraday Trans. 93,2131(1997).
 
 
1-Chloro-n-Butane TT 1-Chloro-n-Butane TG
1-Chloro-n-Butane GT 1-Chloro-n-Butane GG'
 

 








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Last Modified 13 Jan 2008