CHF3







 









Deuterium


Nuclear Quadrupole Coupling Constants


in Trifluoromethane


 








 


 





The deuterium nqcc in trifluoromethane was measured by Kukolich, Nelson, and Ruben [1].  An equilibrium molecular structure was published by Kawashima and Cox [2] in which CH = 1.091(14) ┼.   Demaison and Wlodarczak [3] propose an equilibrium CH bond length of 1.085 ┼.  An ab initio equilibrium structure was derived by Breidung et al. [4].

 








The deuterium nqcc was calculated on the structure of  Kawashima and Cox, on this structure but with the CH bond length of  Demaison and Wlodarczak, and on the "best estimate" equilibrium structure of Breidung.  These nqcc's are compared with the experimental value in Table 1.  The result suggests a bond length between these two.  Therefore, in Table 2, the calculated nqcc is given as a function of CH bond length.  Structure parameters are given in Table 3.

 








 








   







Table 1.  Deuterium nqcc's in CHF3 (kHz).

 







Calc. [a] CH = 1.091 ┼ [2]


Calc. [b] CH = 1.085 ┼ [2,3]


Calc. [c] ab initio re [4]

   








Calc.
Expt. [1]
   







2H Xzz
167.7 [a]
170.8(20)




174.2 [b]






173.0 [c]



 







 








 














Table 2. Calculated deuterium nqcc as a function of CH bond length, with CF3 structure of Kawashima and Cox.
 





r(CH) /┼ Xzz /kHz
 






1.085
174.2


1.086
173.1


1.087
172.0


1.088
170.9


1.089
169.8


1.090
168.7


1.091
167.7






This data suggest a CH bond length of 1.088(2) ┼.  The uncertainty of ▒0.002 ┼ translates to ▒2.2 kHz in the nqcc. The uncertainty in the experimental nqcc is ▒2.0 kHz.


 








 

 
Table 3. Structure parameters, re (┼ and degrees).
 





re [2] re [3] re [4]






CH 1.091 1.085 1.0860

CF 1.3284
1.3312

FCF 108.58
108.44

HCF

110.48


 








 








[1] S.G.Kukolich, A.C.Nelson, and D.J.Ruben, J.Mol.Spectrosc. 40,33(1971); S.G.Kukolich and D.J.Ruben, J.Mol.Spectrosc. 44,607(1972).

[2] Y.Kawashima and A.P.Cox, J.Mol.Spectrosc. 72,423(1978).

[3] J.Demaison and G.Wlodarczak, Struct.Chem. 5,57(1994).

[4] J.Breidung, J.CoslÚou, J.Demaison, K.Sarka, and W.Thiel, Mol.Phys. 102,1827(2004).

 








 








CH3D CDCl3 CD2Br2 CD2(CN)2

CD2F2 CD2Cl2 CD3Br CD3CN

CD3F CD3Cl



 








 








Table of Contents




Molecules/Deuterium




Summary/Methyls  Deuterium nqcc's in substituted methanes.

 








 













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Last Modified 24 Jan 2008