




















_{}
CH_{3}N(H)C(CH_{3})(COOH) 






















Nitrogen 



Nuclear
Quadrupole Coupling Constants 



in NMethylLAlanine
























Calculations of the nitrogen nqcc
tensors in NmethylLalanine was made on MP2/6311++G(d,p) optimized molecular structures (r_{opt}) derived by Neeman et al. [1]
of the conformers shown below. These are two of four different
conformers observed in the microwave spectrum [1].
These calculated nqcc's are compared with the experimental
results in Tables 1 and 2.













Conformer IIa



Conformer IIc







































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 = (X_{xx}  X_{yy})/X_{zz}.



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 B3PW91/6311+G(df,pd) model for calculation of the nitrogen efg's/nqcc's. 































Table 1. Nitrogen
nqcc's in Conformer IIa of NmethylLalanine (MHz). Calculation was made on r_{opt} = MP2/6311++G(d,p) molecular strcuture. 













Calc


Rotamer 2 [1] 










^{14}N 
X_{aa} 

1.868


1.871(9)




X_{bb} 

0.500


0.492(9)




X_{cc} 


2.368



2.362(9)




X_{ab} 

1.309






X_{ac} 


1.640






X_{bc} 

2.812














RMS


0.006 (0.40 %)






RSD


0.030 (1.3 %) 













X_{xx} 

2.084






X_{yy} 

2.663






X_{zz} 


4.748






ETA


0.122












































Table 2. Nitrogen
nqcc's in Conformer IIc of NmethylLalanine (MHz). Calculation was made on r_{opt} = MP2/6311++G(d,p) molecular strcuture. 













Calc


Rotamer 3 [1] 










^{14}N 
X_{aa} 

1.197


1.209(4)




X_{bb} 


3.302



3.255(9)




X_{cc} 

2.105


2.046(9)




X_{ab} 


2.896






X_{ac} 

0.159






X_{bc} 

1.084














RMS


0.044 (2.0 %)






RSD


0.030 (1.3 %) 













X_{xx} 

2.064






X_{yy} 

2.812






X_{zz} 


4.876






ETA


0.153













































[1] E.M.Neeman, I.León, E.R.Alonso, L.Kolesniková, S.Mata, and J.L.Alonso, PCCP, 20,29159(2018).























Table of Contents 





Molecules/Nitrogen 






























NMLA.html 






Last
Modified 10 Dec 2018 









