(CH3)N(H)OH































 









Nitrogen


Nuclear Quadrupole Coupling Constants

in N-Methylhydroxylamine

 








 








Molecular conformation and 14N nuclear quadrupole coupling constants in N-methylhydroxylamine were first investigated by Sung and Harmony [1], and subsequently revisited by Kolesniková et al. [2].

Calculation of the 14N nuclear quadrupole coupling constants was made here on a partial ro molecular structure reported in Ref. [1], and on an ropt structure derived here by MP2/aug-cc-pVTZ optimization.

 








Calculated and experimental nqcc's are compared in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants and 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 experimental diagonal 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 N-Methylhydoxylamine (MHz).  Calculation was made on the ro and ropt structures.
   









Calc /ro
Calc /ropt
Expt [1]
   







Xaa
4.345
4.279
4.35(1)

Xbb
0.730
0.681
0.67(1)

Xcc -
 5.075
 -
 4.960
 -
 5.02(2)

Xab
2.782
2.753
0.2(1)

Xac -
 0.703
 -
 0.678
 -
 0.4(4)

Xbc
2.844
2.909
 -
 3.03(2)

 







RMS
0.047 (1.4 %)
0.054 (1.6 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
0.608
0.642



Xyy
5.911
5.834



Xzz -
 6.519
 -
 6.476



ETA
0.813
0.802



 








 


















   







Table 2. 14N nqcc's in N-Methylhydoxylamine (MHz).  Calculation was made on the ro and ropt structures.
   









Calc /ro
Calc /ropt
Expt [2]
   







Xaa
4.345
4.279
4.3434(96)

Xbb
0.730
0.681
0.7126(72)

Xcc -
 5.075
 -
 4.960
 -
 5.0560(64)

Xab
2.782
2.753



Xac -
 0.703
 -
 0.678



Xbc
2.844
2.909



 







RMS
0.015 (0.44 %)
0.069 (2.0 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 








 








 


Table 3.  N-Methylhydoxylamine:  Structure parameters, ro and ropt (Ĺ and degrees).  For the ro structure, the methyl hydrogen geometry is taken from the ropt structure.





 C
 N,1,R1
 O,2,R2,1,A1
 H,2,R3,1,A2,3,D1,0
 H,3,R4,2,A3,1,D2,0
 H,1,R5,2,A4,3,D3,0
 H,1,R6,2,A5,3,D4,0
 H,1,R7,2,A6,3,D5,0


ro (with uncertainties)          ropt




 R1=1.460(8)
 R2=1.461(10)
 R3=1.007(10)
 R4=0.962(10)
 R5=1.08692431
 R6=1.08980259
 R7=1.0925917
 A1=106.4(5)
 A2=108.3(10)
 A3=100.8(15)
 A4=109.0247985
 A5=107.56296921
 A6=112.7000713
 D1=109.48667641
 D2=-126.4(15)
 D3=71.52217516
 D4=-170.60658985
 D5=-49.74430872
  R1=1.45636916
 R2=1.4454866
 R3=1.01566076
 R4=0.96331518
 R5=1.08692431
 R6=1.08980259
 R7=1.0925917
 A1=106.41457981
 A2=107.93007114
 A3=102.05634129
 A4=109.0247985
 A5=107.56296921
 A6=112.7000713
 D1=109.48667641
 D2=-125.88393826
 D3=71.52217516
 D4=-170.60658985
 D5=-49.74430872







 







 





Table 4.  N--Methylhydoxylamine: Rotational Constants (MHz) and Dipole Moments * (D).
 




Calc /ro Calc /ropt   Expt [1]
    Expt [2]
 



 A
 38832.
 39129.
 38930.771(5)
38930.75277(57)
 B
   9929.
 10033.
   9939.607(2)
  9939.618023(99)
 C
   8677.
   8778.
   8690.716(1)
  8690.696797(91)
 
|µa|
 0.694
 0.639
 0.611(8)
|µb| 0.480
 0.438
 0.366(37)
|µc| 0.054
 0.061
   ------





* Calculated on the indicated structure by B3PW91/6-311+G(df,pd) method.



 








 








[1] E.-M.Sung and M.D.Harmony, J.Mol.Spectrosc. 74,228(1979).

[2] L.Kolesniková, E.R.Alonso, S.Mata, and J.L.Alonso, J.Mol.Spectrosc. 335,54(2017).

 








 








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Molecules/Nitrogen




 








 













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Last Modified 17 March 2017