|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
H2N-CH(CH3)-C(=O)OH |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nitrogen |
|
|
|
Nuclear
Quadrupole Coupling Constants |
|
|
in Alanine
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Calculations of the 14N nqcc
tensors in the conformers of alanine shown below were made on ropt molecular structures given by MP2/6-311++G(d,p) and B3LYP/cc-pVTZ optimization.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Conformer I |
|
|
Conformer IIa |
|
|
|
|
|
|
|
|
|
|
|
|
|
Calculated and experimental [1] nqcc's are compared
in Tables 1 and 2.
Structure
parameters are given here in Z-matrix format. Rotational are given in Table 3. |
|
|
|
|
|
|
|
|
|
|
|
|
In Table 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 experimental diagonal nqcc's
(percentage of the average of the magnitudes of the experimental
nqcc's). RSD is the calibration residual
standard deviation of
the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen efg's/nqcc's. |
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
Table 1. 14N
nqcc's in Alanine, conformer I (MHz).
Calculation was made on MP2/6-311++G(d,p) and B3LYP/cc-pVTZ ropt molecular structures. |
|
| |
|
|
|
|
|
|
|
|
|
|
|
Calc /MP2
|
|
Calc /B3LYP |
|
Expt [1]
|
|
| |
|
|
|
|
|
|
|
|
|
Xaa |
-
|
3.361
|
-
|
3.574
|
-
|
3.2567(11)
|
|
|
Xbb |
|
1.924
|
|
1.988
|
|
2.0093(16)
|
|
|
Xcc |
|
1.437
|
|
1.586
|
|
1.2474(16)
|
|
|
Xab |
|
2.414
|
|
2.400
|
|
|
|
|
Xac |
-
|
1.535
|
-
|
1.187
|
|
|
|
|
Xbc |
|
0.505
|
|
0.382
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RMS
|
|
0.134 (6.1 %)
|
|
0.268 (12.3 %)
|
|
|
|
|
RSD |
|
0.030 (1.3 %)
|
|
0.030 (1.3 %) |
|
|
|
|
|
|
|
|
|
|
|
|
|
Xxx |
|
1.854
|
|
1.829
|
|
|
|
|
Xyy |
|
2.867
|
|
2.884
|
|
|
|
|
Xzz |
-
|
4.721
|
-
|
4.713
|
|
|
|
|
ETA |
|
0.215
|
|
0.224
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
Table 2. 14N
nqcc's in Alanine, conformer IIa (MHz).
Calculation was made on MP2/6-311++G(d,p) and B3LYP/cc-pVTZ ropt molecular structures.
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
Calc /MP2
|
|
Calc /B3LYP |
|
Expt [1]
|
|
| |
|
|
|
|
|
|
|
|
|
Xaa |
|
0.781
|
|
0.493
|
|
0.4515(17)
|
|
|
Xbb |
|
0.261
|
|
0.360
|
|
0.3267(21)
|
|
|
Xcc |
-
|
1.042
|
-
|
0.853
|
-
|
0.7782(21)
|
|
|
Xab |
|
2.049
|
|
2.219
|
|
|
|
|
Xac |
-
|
1.940
|
-
|
2.093
|
|
|
|
|
Xbc |
|
2.373
|
|
2.256
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RMS
|
|
0.246 (47.5 %)
|
|
0.053 (10.3 %)
|
|
|
|
|
RSD |
|
0.030 (1.3 %) |
|
0.030 (1.3 %) |
|
|
|
|
|
|
|
|
|
|
|
|
|
Xxx |
|
1.772
|
|
1.786
|
|
|
|
|
Xyy |
|
2.596
|
|
2.650
|
|
|
|
|
Xzz |
-
|
4.368
|
-
|
4.436
|
|
|
|
|
ETA |
|
0.189
|
|
0.195
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Table 3. Alanine.
Rotational Constants (MHz). |
|
|
|
|
|
|
Calc /MP2 |
Calc /B3LYP |
Expt [1]
|
|
|
|
|
|
| Conformer I |
A |
5074.
|
5072.
|
5066.14560(42)
|
|
B |
3050.
|
3052.
|
3100.95058(29)
|
|
C |
2298.
|
2275.
|
2264.01342(24)
|
|
|
|
|
|
| Conformer IIa |
A |
4993.
|
4976.
|
4973.05578(61)
|
|
B |
3197.
|
3225.
|
3228.33792(45)
|
|
C |
2344.
|
2299.
|
2307.8087(34)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
[1] S.Blanco, A.Lesarri, J.C.López, and J.L.Alonso, J.Am.Chem.Soc. 126,11675(2004).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sarcosine
|
Paracetamol
|
Phenylglycinol
|
Tyrosine
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Table of Contents |
|
|
|
|
|
Molecules/Nitrogen |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Alanine.html |
|
|
|
|
|
|
Last
Modified 4 April 2015 |
|
|
|
|
|
|
|
|
|
|