C4H7Br
























 









Bromine


Nuclear Quadrupole Coupling Constants


in equatorial Bromocyclobutane


 








 








 








Calculation of the bromine nqcc's in equatorial bromocyclobutane was made on an adjusted ro molecular structure derived by Durig et al. [1].  Calculated and experimental [1] nqcc's are compared in Table 1.  Structure parameters are given in Table 2.

 








In Table 1, RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation for the B1LYP/TZV(3df,3p) model for calculation of the bromine nqcc's. 

 








Subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia b-axis, these are perpendicular to the molecular symmetry plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

 








 








 
   







Table 1. Bromine nqcc's in equatorial bromocyclobutane (MHz).
   










Calc.
Expt. [1]
   







79Br Xaa
461.72
450.1(15)


Xbb - 261.11 - 249(14)


Xcc - 200.62 - 201(14)


|Xac|
225.30
129(35)

 







RMS
9.7 (3.2 %)




RSD
1.58 (0.39 %)



 







Xxx - 269.99




Xyy - 261.11




Xzz
531.10




ETA - 0.0167




Øz,a
17.11




Øa,CBr
16.03




Øz,CBr
  1.08



   





81Br Xaa
385.87
373.8(13)


Xbb - 218.15 - 215(13)


Xcc - 167.72 - 159(13)


|Xac|
188.07
147(30)

 







RMS
8.8 (3.5 %)




RSD
1.38 (0.40 %)



 







 








 











Table 2.  Bromocyclobutane, equatorial.  Heavy atom structure parameters, ro (Å and degrees).  The complete structure is given here in Z-Matrix format.
 


C(1)Br 1.942(3)
C(1)C(2,3) 1.541(3)
C(2,3)C(4) 1.552(3)
C(2,3)C(1)Br 118.4(5)
C(2)C(1)C(3)   89.7(5)
C(1)C(2,3)C(4)   86.8(5)
C(1)C(2)C(3)C(4)   29.8(5)





 








 








[1] J.R.Durig, J.J.Klaassen, A.Ganguly, and P.Groner, J.Mol.Struct. 934,66(2009).

 








W.G.Rothschild and B.P.Dailey, J.Chem.Phys. 36(11),2931(1962): Xaa = 450.1(19),  Xbb = -256.6(71), Xcc = -193.5(68) MHz.


 









 









Cyclohexyl Bromide, equatorial Cyclohexyl Bromide, axial

 








 








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Molecules/Bromine




 








 













BrCyclobutane_eq.html






Last Modified 1 July 2009