




















CFCl_{3} 


















Chlorine 



Nuclear
Quadrupole Coupling Constants 



in Trichlorofluoromethane 























^{35}Cl nqcc's in trichlorofluoromethane were first measured
in 1967 by Wolf et al. [1], and revisited in 1987 by Carpenter et al. [2].
Loubser, 1961 [3] and Long et al., 1960 [4] determined effective structures. 












Coupling constants calculated here are compared
with the experimental nqcc's [2] in Tables 1 and 2. It will be seen
that good agreement with the experimental nqcc's is obtained on a structure
that is an average of the structures of Loubser and Long et al. Structure
parameters and atomic coordinates (of this average effective structure)
are given in Tables 3 and 4, respectively. 






















Coordinate Systems 


X_{uu} is the component of the nqcc tensor along the threefold
symmetry axis. Corresponding to the atomic coordinates given below
in Table 4, X_{vv} and X_{ww} are the components along the
v and w axes for the Cl atom in the uvplane. ETA_{Q}
= (X_{vv}  X_{ww})/X_{uu}. 


The subscripts x,y,z refer to the principal axes of the nqcc tensor.
The nqcc yaxis is chosen coincident with the waxis. Ø (degrees)
is the angle between its subscripted parameters. ETA = (X_{xx}
 X_{yy})/X_{zz}. 












RMS is the root mean square
difference between calculated and experimental diagonal nqcc's.
RSD is the residual standard deviation of calibration of the
model for calculation of the nqcc's. 






























Table 1. ^{35}Cl nqcc's in CFCl_{3} (MHz). 










Calc. [3] r_{o}
structure of Loubser. 



Calc. [4] r_{o}
structure of Long et al. 










Calc [3]

Calc [4] 

Expt. [2] 









X_{uu} 
_{}29.87 
27.54 

28.98(4) 


ETA_{Q} 
 3.77 
 4.00 

 3.85(20) 































As mentioned above, it is evident that a structure somewhere between
that of Loubser and that of Long et al. would give calculated parameters
in better agreement with the experimental values. Calculation was made,
therefore, on a structure that is a simple average of these two. This result
is shown in Table 2. 































Table 2. Chlorine nqcc's in CFCl_{3} (MHz). 













Calc. 

Expt. [2] 










^{35}Cl 
X_{uu} 

28.76 

28.98(4) 



ETA_{Q} 

 3.89 

 3.85(20) 



X_{vv} 
 
70.16 
 
70.28 * 



X_{ww} 

41.40 

41.30 * 



X_{uv} 

34.58 













RMS 

0.15 (0.33 %) 




RSD 

0.49 (1.1 %) 













X_{xx} 

39.63 





X_{yy} 

41.38 





X_{zz} 
 
81.01 
 
83(6) 



ETA 

0.022 

0 (Assumed) 



Ø_{z,u} 

72.52 





Ø_{u,CCl} 

71.42 





Ø_{z,CCl} 

1.10 
























* Calculated here from the experimental X_{uu}
and ETA_{Q}. 












The pyramid formed by the zprincipal axes of the three Cl nqcc tensors
is somewhat 'flatter' than the molecular pyramid. This is typical of
the pyramidal trichlorides. 

















Table 3. Molecular structure parameters (Å and degrees). 







r_{o }[3] 
r_{o }[4] 
avg. r_{o} 






CF 
1.362 
1.33 
1.346 

CCl 
1.754 
1.76 
1.757 

ClCCl 
111 
109.7 
110.35 





















Table 4. Atomic coordinates, average r_{o }structure. 
(More figures are shown than are significant.) 











u (Å) 

v (Å) 

w (Å) 









Cl 
 
0.310763 

1.665449 

0.0 

Cl 
 
0.310763 
 
0.832725 
± 
1.442321 

C 

0.248994 

0.0 

0.0 

F 

1.594994 

0.0 

0.0 























[1] A.A.Wolf, Q.Williams, and T.L.Weatherly, J.Chem.Phys. 47,5101(1967). 


[2] J.H.Carpenter, P.J.Seo, and D.H.Whiffen, J.Mol.Spectrosc. 123,187(1987). 


[3] J.H.N.Loubser, J.Chem.Phys. 36,2808(1961). 


[4] M.W.Long, Q.Williams, and T.L.Weatherly, J.Chem.Phys. 33,508(1960). 






















CF_{3}Cl_{} 
_{}CF_{2}Cl_{2} 
CH_{3}CCl_{3} 
OPCl_{3} 


NCl_{3} 
PCl_{3} 
AsCl_{3} 
SPCl_{3} 


CH_{3}Cl 
CH_{2}Cl_{2} 
SiHCl_{3} 























Table of Contents 





Molecules/Chlorine 






























CFCl3.html 






Last
Modified 3 June 2003 









