4-I-C5NH4

























 





 








Nitrogen and Iodine

Nuclear Quadrupole Coupling Constants


in 4-Iodopyridine


 








 








 

 





Nitrogen and iodine nqcc tensors in 4-Iodopyridine were calculated on a structure given by B3P86 optimization with 6-31G(3d,3p) bases for H, C, and N, and 6-311G(3d) for I.  Calculated and experimental nqcc's are shown in Table 1.  Structure parameters are given in Table 2, atomic coordinates in Table 3, and rotational constants in Table 4.

 








In Tables 1 and 2, 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 c-axis, these are perpendicular to the molecular plane.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percent of average absolute experimental nqcc).  RSD is the calibration residual standard deviation of the model for calculation of the nqcc's.

 








 








   






Table 1. Nitrogen and Iodine nqcc's in 4-Iodopyridine (MHz).  Calculation was made on the B3P86 ropt structure.
   









Calc.
Expt. [1]
   






14N Xaa - 4.895




Xbb
1.478




Xcc
3.418




ETA *
0.396



 







RMS






RSD
0.030 (1.3 %)



 






127I Xaa -
 1929.3
 -
 1938(2)


Xbb
1024.4
1008(2)


Xcc
  904.9
  930(2)


ETA * - 0.0619



 







RMS
18.0 (1.40 %)




RSD
15.2 (1.23 %)



 







 








* ETA = (Xbb - Xcc)/Xaa = (Xxx - Xyy)/Xzz.

 







 
   



Table 2.  4-Iodopyridine, and for comparison, 4-Bromopyridine and Pyridine.  Molecular structure parameters, ropt (Å and degrees).

 






  4-I
  4-Br
 Pyridine








N(1)C(2) 1.3322
 1.3321 1.3336


C(2)C(3) 1.3917
 1.3898 1.3904


C(3)C(4) 1.3881
 1.3861 1.3885


C(2)H(2) 1.0878
 1.0875 1.0880


C(3)H(3) 1.0830
 1.0821 1.0845


C(4)I/Br/H 2.1076
 1.8724 1.0851


C(6)N(1)C(2) 116.90
 116.79 117.03


N(1)C(2)C(3) 124.14
 124.16 123.80


C(2)C(3)C(4) 117.73
 117.77 118.44


C(3)C(4)C(5) 119.36
 119.35 118.50


N(1)C(2)H(2) 116.25
115.94


C(2)C(3)H(3) 120.59
120.21



 








 














Table 3.  4-Iodopyridine.  Atomic coordinates, ropt. 
 







  a (Å)
  b (Å)







N(1) - 3.5475
0.0

C(2,6) - 2.8505 ± 1.1353

C(3,5) - 1.4602
 ± 1.1982

C(4) - 0.7595
0.0

H(2,6) - 3.4302
 ± 2.0558

H(3,5) - 0.9518 ± 2.1544

I(4)
1.3481
0.0


 








 












Table 4.  4-Iodopyridine.  Rotational Constants (MHz). 
 




Calc. ropt     Expt. [1]





A  6069.4 6015.0(5)

B    737.2
   741.91(1)

C    657.4
   660.45(1)



 








 








[1] W.Caminati and P.Forti, Chem.Phys.Lett. 29,239(1974).

 








 








Iodobenzene
Pyridine 2-Iodopyridine


2-Bromopyridine 2-Chloropyridine

3-Bromopyridine 3-Chloropyridine

4-Bromopyridine 4-Chloropyridine

 








 








Table of Contents





Molecules/Nitrogen




Molecules/Iodine




 








 













4IPyridine.html






Last Modified 19 Aug 2011