CH3SiBr3

































 









Bromine


Nuclear Quadrupole Coupling Constants


in Methyltribromosilane


 








 


 





 








The microwave spectrum of methyltribromosilane was observed by Mitzlaff et al. [1], which authors derived by least squares analysis of the rotation constants 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 CH3SiBr3 (MHz).  Calculation was made on the ro structure [1].


 
 









Calc.
Expt.


 








79Br
Xuu -
130.46





Xvv
302.89





Xww -
164.42





Xuv -
138.46



 









Xxx -
169.34





Xyy -
164.42





Xzz
333.76





ETA - 0.0147





z,u
104.3





u,SiBr
107.8





z,SiBr
  13.5



 








 








 








 


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




  ro





CSi 1.90


SiBr 2.17495


CH 1.093

  BrSiBr
111.09


HCH
109.39







 








 
















Table 3.  Methyltribromosilane.  Heavy atom coordinates, ro











 u ()
 v ()
 w ()









Si
0.4567
0
0

Br - 0.2081
2.0708
0

Br - 0.2081 - 1.0354 1.7934

C
2.3567
0
0

H
2.7225 -
1.0300
0

H
2.7225
0.5150 0.8920


 








 








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

 








 








SiHBr3
SiFBr3 CHBr3 CH3CBr3











 








Table of Contents




Molecules/Bromine




 








 













CH3SiBr3.html






Last Modified 24 Jan 2017