




















H_{3}CCCl_{3} 



PDF
























Chlorine 



Nuclear
Quadrupole Coupling Constants 


in
Methyl Chloroform























The complete chlorine nqcc tensor in
methyl chloroform was
determined by Dore and Kisiel [1]. Carpenter et al. [2] had
previously
determined the component along the CCl bond. An effective
molecular
structure was reported by Holm et al. [3]. An ab initio equilibrium structure was
derived by Margulès et al. [4]. 












Calculation of the chlorine nqcc's
in methyl chloroform was made on a molecular structure derived ab
initio, with bond length corrections (see below). These are
compared with
the experimental values in Tables 1 and 2. Structure parameters
and atomic coordinates are given in Tables 3 and 4, respectively. 












The results of calculation made on
the effective molecular structure of Holm et al. can be seen here. 


The results of calculation made on
the ab initio equilibrium
structure of Margulès et al. can be seen here. 






















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. 












Subscripts x,y,z refer to the principal axes of the nqcc
tensor. The 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 caalculated and experimental diagonal nqcc's
(percent of the average experimental nqcc). RSD is the residual
standard deviation of calibration of the model for calculation of the
nqcc's. 































Table 1. Chlorine nqcc's
in H_{3}CCCl_{3} (MHz). The subscripts cc, etc.
in parentheses are the axes labels of Ref. [1]. 













Calc. 

Expt. [1] 










^{35}Cl 
X_{uu(cc)} 

26.92 

26.8907(9) 



X_{vv(aa)} 
 
65.74 
 
65.5378(12) 



X_{ww(bb)} 

38.82 

38.6472(12) 



X_{uv(ac)} 

36.66 

36.510(23) 











RMS 

0.15 (0.35 %) 





RSD 

0.49 (1.1 %) 













X_{xx} 

39.68 

39.571(14) 



X_{yy} 

38.82 

38.6472(12) 



X_{zz} 
 
78.49 
 
78.218(14) 



ETA 
 
0.0109 
 
0.0118(2) 



Ø_{z,u} 

70.82 

70.846(9) 



Ø_{u,CCl} 

69.80 

69.82 * 



Ø_{z,CCl} 

1.03 

1.05 * 






















* Calculated here. 
















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 2. ^{37}Cl
nqcc's in ^{37}Cl^{35}Cl_{2}CCH_{3}
(MHz). 













Calc. 

Expt. [1] 










^{37}Cl 
X_{aa} 
 
52.46 


52.3028(16) 



X_{bb} 

30.59 

30.4585(16) 



X_{cc} 

21.87 

21.8443(11) 



X_{ac} 

28.05 

28.032(76) 











RMS 

0.12 (0.35 %) 





RSD 

0.44 (1.1 %) 













X_{xx} 

31.27 

31.249(46) 



X_{yy} 

30.59 

30.4585(16) 



X_{zz} 
 
61.86 
 
61.708(46) 



ETA 
 
0.0109 
 
0.0128(7) 



Ø_{z,c} 

71.48 

71.45(4) 



Ø_{c,CCl} 

70.45 

70.45 * 



Ø_{z,CCl} 

1.03 

1.00 * 






















* Calculated here. 

























Molecular Structure 












The molecular structure was optimized
at the MP2/6311+G(d,p) level of theory assuming C_{s}
symmetry. The optimized CC single bond length was then corrected
using the equation obtained from linear regression analysis of the data
given in Table IX of Ref. [7]. Likewise, the optimized CF bond
lengths were corrected by regression analysis of the data given in
Table VI of Ref. [6]. For the CCl bond, the structure was
optimized at the MP2/6311+G(2d,p) level and corrected by linear
regression analysis of the data given in Table 4 of Ref. [5]. The
CH bond lengths were corrected using r = 1.001 r_{opt},
where r_{opt} is obtained by MP2/631G(d,p) optimization [8].
Interatomic angles used in the calculation are those given by
B3P86/6311+G(3d,3p)
optimization. 
















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





CCl 
1.7724 


CC 
1.507 


CH 
1.087 


CCH 
109.33 


CCCl 
110.20 






















Table 3. Atomic coordinates. 
(More figures are shown than
are significant.) 











u (Å) 

v (Å) 

w (Å) 









Cl 
 
0.360966 

1.663358 

0.0 

Cl 
 
0.360966 
 
0.831679 
± 
1.440510 

C 

0.251115 

0.0 

0.0 

C 

1.758115 

0.0 

0.0 

H 

2.117952 
 
1.025713 

0.0 

H 

2.117952 

0.512856 
± 
0.888293 























[1] L.Dore and Z.Kisiel,
J.Mol.Spectrosc. 189,228(1998). 


[2] J.H.Carpenter, P.J.Seo, and
D.H.Whiffen, J.Mol.Spectrosc. 120,219(1986). 


[3] R.Holm, M.Mitzlaff, and
H.Hartmann, Z.Naturforsch. 23a,307(1968). 


[4] L.Margulès, M.Carvajal,
and J.Demaison, J.Mol.Spectrosc. 247,160(2008). 


[5] I.Merke, L.Poteau, G.Wlodarczak,
A.Bouddou, and J.Demaison, J.Mol.Spectrosc. 177,232(1996). 


[6] R.M.Villamañan, W.D.Chen,
G.Wlodarczak, J.Demaison, A.G.Lesarri, J.C.López, and
J.L.Alonso,
J.Mol.Spectrosc. 171,223(1995). 


[7] J.Demaison, J.Cosléou,
R.Bocquet, and A.G.Lesarri, J.Mol. Spectrosc. 167,400(1994). 


[8] J.Demaison and G.Wlodarczak,
Structural Chem. 5,57(1994). 






















CFCl_{3} 
SiHCl_{3} 
F_{3}CCCl_{3} 
OPCl_{3} 


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


CH_{3}Cl 
_{}CH_{2}Cl_{2} 
CHCl_{3} 
CH_{3}CH_{2}Cl 












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