SiFBr3

































 









Bromine


Nuclear Quadrupole Coupling Constants


in Fluorotribromosilane


 








 


 





 








The microwave spectrum of fluorotribromosilane was observed by Mitzlaff et al. [1], which authors derived an ro molecular structure.


Calculation was made here of the bromine nqcc's on the this structure.  The results are given in Table 1.  Structure parameters are given in Table 2, atomic coordinates in Table 3.

 








 








Coordinate Systems











Xuu is the component of the nqcc tensor along the threefold symmetry axis.  Corresponding to the atomic coordinates given below in Table 3, Xvv and Xww are the components along the v- and w- axes for the Br atom in the uv-plane.

Subscripts x,y,z refer to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the w-axis.  (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.











 








   








Table 1.  Bromine nqcc's in SiFBr3 (MHz).  Calculation was made on the ro structure [1].


 
 









Calc.
Expt.


 








79Br
Xuu -
134.35





Xvv
314.57





Xww -
180.22





Xuv -
138.72



 









Xxx -
173.76





Xyy -
180.22





Xzz
353.98





ETA
0.0182





z,u
105.9





u,SiBr
107.5





z,SiBr
    1.6




 








 








 








 


Table 2.  Fluorotribromosilane.  Molecular structure parameters [1] ( and degrees).
 




  ro





SiF 1.5607


SiBr 2.1706

  BrSiBr
111.36







 








 
















Table 3.  Fluorotribromosilane.  Heavy atom coordinates, ro











 u ()
 v ()
 w ()









Si
0.4404
0
0

F

2.0011

0

0

Br -
0.2126
2.0700
0

Br - 0.2126 - 1.0350 1.7927


 








 








[1] M.Mitzlaff, R.Holm, and H.Hartmann. Z.Naturforsch. 23a,1819(1968).

 








 








SiHBr3
CH3SiBr3 CHBr3 CH3CBr3











 








Table of Contents




Molecules/Bromine




 








 













SiFBr3.html






Last Modified 25 Jan 2017