CH2F-CH2NH2















 








 









Nitrogen


Nuclear Quadrupole Coupling Constants

in 2-Fluoroethylamine

 








 








 

 





The microwave spectrum of 2-fluoroethylamine has been investigated by Marstokk and Møllendal [1].

Calculation of the 14N nuclear quadrupole coupling constant tensor in each of the following rotamers of the title molecule was made here on ropt molecular structures given by MP2/6-311+G(3df,3pd) and MP2/aug-cc-pVTZ optimization.

 








Conformer I

Conformer II






EI < EII by 1.2 kJ/mole

at MP2/aug-cc-pVTZ

level of theory.









 








 








Calculated and experimental nitrogen nqcc's are compared in Tables 1 and 2.  Structure parameters are shown in Table 3, rotational constants and electric dipole moments 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.  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.  14N nqcc's in 2-Fluoroethylamine, conformer I (MHz).  Calculation was made on (1) MP2/6-311+G(3df,3pd) and (2) MP2/aug-cc-pVTZ ropt structures.
   









Calc (1)
Calc (2)
Expt [1]
   







Xaa
2.184
2.174
2.02(13)

Xbb
2.453
2.451
2.49(10)

Xcc -
 4.637
 -
 4.625
 -
 4.51

Xab
0.458
0.470



Xac
0.271
0.321



Xbc -
 0.624
-
 0.664


 







RMS
0.163 (5.4 %)
0.114 (3.8 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
2.812
2.819



Xyy
1.893
1.887



Xzz -
 4.705
 -
 4.706



ETA
 -
 0.195
 -
 0.198



 








 








 








   







Table 2.  14N nqcc's in 2-Fluoroethylamine, conformer II (MHz).  Calculation was made on (1) MP2/6-311+G(3df,3pd) and (2) MP2/aug-cc-pVTZ ropt structures.
   









Calc (1)
Calc (2)
Expt [1]
   







Xaa -
 3.077
 -
 3.049
 -
 2.78(14)

Xbb
2.427
2.425
2.34(8)

Xcc
0.650
0.624
0.44

Xab
0.702
0.703



Xac -
 2.942
 -
 2.954



Xbc -
 0.138
-
 0.141


 







RMS
0.216 (11.7 %)
0.194 (10.5 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
2.838
2.840



Xyy
1.901
1.892



Xzz -
 4.739
 -
 4.732



ETA
 -
 0.198
 -
 0.200



 








 








 


















Table 3.  2-Fluoroethylamine Optimized Structure Parameters (Å and degrees).  ropt(1) = MP2/6-311+G(3df,3pd), ropt(2) = MP2/aug-cc-pVTZ.
 









 C
 C,1,B1
 F,1,B2,2,A1
 H,1,B3,2,A2,3,D1,0
 H,1,B4,2,A3,3,D2,0
 H,2,B5,1,A4,3,D3,0
 H,2,B6,1,A5,3,D4,0
 N,2,B7,1,A6,3,D5,0
 H,8,B8,2,A7,1,D6,0
 H,8,B9,2,A8,1,D7,0











Conformer I
Conformer II

ropt(1) ropt(2)
ropt(1)
 ropt(2)
B1
B2
B3
B4
B5
B6
B7
B8
B9
A1
A2
A3
A4
A5
A6
A7
A8
D1
D2
D3
D4
D5
D6
D7
 1.50491959
1.39391126
1.08861846
1.08825087
1.09063184
1.09528062
1.45761797
1.01160972
1.01286005
108.95494151
111.47030586
110.73482589
107.84901112
108.47336207
109.35944716
110.7354402
109.39956671
118.54464206
-117.9041167
-177.15635242
-60.59157995
64.60414375
-179.75438031
-62.45307099
 1.50453121
1.39968457
1.08934049
1.08886659
1.09151919
1.09582947
1.45993928
1.01208417
1.01336204
108.97444213
111.54748974
110.85040367
107.83855491
108.47869298
109.43548963
110.62069262
109.33595753
118.51230073
-117.83067203
-177.02195008
-60.52816239
64.73827359
-179.32263754
-62.0454053
1.51150796
1.3916306
1.08994781
1.09035478
1.09102256
1.08987985
1.45507
1.01251928
1.01268652
109.22816767
111.51494107
111.31532785
108.28790946
108.62283759
115.09650402
109.5895073
110.50966628
118.872535
-118.28801179
-176.81938821
-60.71843997
60.87055356
-56.00766006
61.25460641
 1.51161278
1.39719423
1.0906753
1.09104317
1.09188472
1.0905544
1.45703284
1.01320069
1.01334072
109.25881012
111.56127992
111.419134
108.24124969
108.63638838
115.2690328
109.52000369
110.44755611
118.81351214
-118.21785652
-176.69878853
-60.69998736
60.97548919
-55.83383534
61.29905943













 







 





Table 4.  2-Fluoroethylamine. Rotational Constants (MHz) and Dipole Moments * (D).  ropt(1) = MP2/6-311+G(3df,3pd), ropt(2) = MP2/aug-cc-pVTZ.

 



Conf I
 ropt(1) ropt(2)      Expt [1]

 



A
 15 463.9
 15412.7
 15 437.6657(82)

B
   5396.1
   5376.9
   5 302.3944(28)

C
   4503.3
   4487.4
   4 439.5230(21)

µa
   1.15
   1.15
 1.148(3)

µb   1.38
   1.40
 1.380(8)

µc   0.87
   0.86
 0.332(21)

µtot   1.99
   2.00
 1.826(12)

 



Conf II



 



A
 15 247.6
 15 212.4
 15 186.4940(77)

B
   5290.7
   5265.7
   5 222.0616(28)

C
   4453.3
   4433.3
   4 400.7600(23)

µa   0.11
   0.10
 < 0.03

µb   1.41
   1.43
 1.337(8)

µc   1.14
   1.16
 1.002(5)

µtot   1.82
   1.84
 1.671(10)

 



* Calculated by B3PW91/6-311+G(df,pd) method on MP2 ropt structures.



 








 








[1] K.-M.Marstokk and H.Møllendal, Acta Chem.Scand. A 34,15(1980).

 








 








CH3NH2 CH3CH2NH2



 








 








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Molecules/Nitrogen




 








 













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Last Modified 20 Oct 2013