




















CH_{2}F_{2} 


















Deuterium 



Nuclear
Quadrupole Coupling Constants 



in Difluoromethane 

































Deuterium nqcc's along carbonhydrogen bond direction in deuterated
difluoromethane have been reported by Nelson et al. [1]. An equilibrium
structure has been reported by Hirota [2]. 












Calculation of the deuterium nqcc's was
made here on the equilibrium structure. These results are shown in
Table 1. The structure parameters are given in Table 2. Sensitivity
of the principal values of the nqcc tensor to CH bond length and HCH angle,
within the uncertainties in the equilibrium structure, was investigated.
This result is shown in Table 3. 












In Table 1, the subscripts a,b,c refer to
the principal axes of the inertia tensor, the subscripts x,y,z to the principal
axes of the nqcc tensor. The nqcc yaxis is chosen coincident with
the inertia aaxis, these are perpendicular to the HCH plane. Ø
(degrees) is the angle between its subscripted parameters. ETA = (X_{xx}
 X_{yy})/X_{zz}. 































Table 1. Deuterium nqcc's
in CD_{2}F_{2 }(kHz). 













Calc. 

Expt. [1] 










^{2}H 
X_{aa} 

 86.6 





X_{bb} 

 8.8 





X_{cc} 

95.4 





X_{bc} 
± 
126.3 













X_{xx} 

 93.4(20) 





X_{yy} 

 86.6(19) 





X_{zz} 

179.9(36) * 

186(10) ** 



ETA 
 
0.038 
 
0.15(5) 



Ø_{z,b} 

33.79 





Ø_{b,CD} 

33.6 





Ø_{z,CD} 

0.2 
























* See below for estimates of the uncertainties in the
principal values of the nqcc tensor.



** Bond axis nqcc.


























Table 2. Molecular structure parameters, r_{e }[2] (Å
and degrees). 




CF 
1.3508 

CH 
1.084(3) 

HCH 
112.8(3) 

FCF 
108.49 































Table 3. Sensitivity
of the principal values of the nqcc tensor (kHz) to CH = 1.084±0.003
Å and HCH = 112.8±0.3^{o}, which are the uncertainties
in the r_{e} structure. 









CH 
HCH 
X_{xx} 
X_{yy} 
X_{zz} 









1.084 
112.5 
 93.4 
 86.5 
180.0 


1.084 
112.8 
 93.4 
 86.6 
179.9 


1.084 
113.1 
 93.3 
 86.6 
179.9 









1.081 
112.8 
 95.1 
 88.2 
183.3 


1.084 
112.8 
 93.4 
 86.6 
179.9 


1.087 
112.8 
 91.7 
 85.0 
176.6 































Estimate of the uncertainty in X_{zz} is 













X_{zz} = X_{zz }± [(3.4)^{2} + (1.1)^{2}]^{1/2
}= 179.9(36) kHz 












where ±3.4 kHz is due to the
uncertainty in the CH
bond length (Table 3) and ±1.1 kHz is the calibration residual
standard deviation of the B3LYP/631G(df,3p) model for calculation of
the nqcc's. The nqcc's are not sensitive to the uncertainty in
the HCH angle. 






















[1] A.C.Nelson, S.G.Kukolich, and D.J.Ruben, J.Mol.Spectrosc. 51,107(1974). 


[2] E.Hirota, J.Mol. Spectrosc. 71,145(1978). 






















_{}CDH_{3} 
CDF_{3} 
CD_{3}F 
CD_{2}Cl_{2} 


CDCl_{3} 
CD_{3}Cl 
CD_{2}Br_{2} 
_{}CD_{3}Br 


CD_{3}CN 
CD_{2}(CN)_{2} 
HCCCD_{3} 
CD_{n}X_{4n} 






















Table of Contents 





Molecules/Deuterium 





Summary/Methyls
Deuterium nqcc's in the substituted methanes. 



























CH2F2.html 






Last
Modified 30 May 2003 









