C5H10N2O3











 


























 









Nitrogen


Nuclear Quadrupole Coupling Constants

in N-Acetyl-L-Serinamide

 








 








 

 





Calculation of the 14N nuclear quadrupole coupling constant tensors in N-acetyl-L-serinamide (Ac-Ser-NH2) was made here on ropt molecular structures given by MP2/6-311++G(d,p) [1] and B3P86/6-31G(3d,3p) optimization.

 








Calculated and experimental [1] nitrogen nqcc's are compared in Tables 1 and 2.  Structure parameters are given here in Z-Matrix format.  Rotational constants are given in Table 3.

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.  ETA = (Xxx - Xyy)/Xzz.  RMS is the root mean square difference between calculated and experiment diagonal nqcc's (percent of average magnitude of experimental nqcc's).  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's. 


 








 








   







Table 1.  14Nc (central nitrogen) nqcc's in Ac-Ser-NH2 (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) B3P86/6-31G(3d,3p) ropt structures.
   









Calc (1)
Calc (2)
Expt [1]
   







Xaa
1.929
1.887
1.9538(28)

Xbb -
 0.418
 -
 0.430
 -
 0.5099(41)

Xcc -
 1.511
 -
 1.458
 -
 1.4439(41)

Xab -
 0.384
 -
 0.384



Xac
1.024
1.818



Xbc
2.662

 2.628


 







RMS
0.067 (5.2 %)
0.061 (4.6 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.546
1.520



Xyy
2.322
2.289



Xzz -
 3.868
 -
 3.808



ETA
0.201
0.202



 








 








 








   







Table 2.  14Nt (terminal nitrogen) nqcc's in Ac-Ser-NH2 (MHz).  Calculation was made on (1) MP2/6-311++G(d,p) and (2) B3P86/6-31G(3d,3p) ropt structures.
   









Calc (1)
Calc (2)
Expt [1]
   







Xaa
0.529
0.592
0.5880(31)

Xbb
1.340
1.329
1.4018(48)

Xcc -
 1.869
 -
 1.921
 -
 1.9898(48)

Xab -
 0.964
 -
 0.886



Xac -
 1.565
 -
 1.458



Xbc -
 1.679
-
 1.716


 







RMS
0.085 (6.4 %)
0.058 (4.3 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.286
1.252



Xyy
2.139
2.128



Xzz -
 3.425
 -
 3.380



ETA
0.249
0.259



 








 








 







 





Table 3.  Ac-Ser-NH2.  Rotational Constants (MHz).  ropt(1) = MP2/6-311++G(d,p), ropt(2) = B3P86/6-31G(3d,3p).

 




ropt(1) ropt(2)      Expt [1]

 



A
 1855.0
 1895.8
 1879.8183(73)

B
 1007.2
 1010.0
 1001.544607(93)

C
   754.0
   757.8
   750.65138(13)



 








 








[1] C.Cabezas, M.A.T.Robben, A.M.Rijs, I.Peņa, and J.L.Alonso, Phys.Chem.Chem.Phys. 17,20274(2015).

 








 








Table of Contents




Molecules/Nitrogen




 








 













AcSerNH2.html






Last Modified 4 Nov 2017