Morpholine


OC4H8N-H


 








 








 









Nitrogen and Deuterium


Nuclear Quadrupole Coupling Constants

in Morpholine (chair, eq and ax)


 








 








 


 





Calculation of the nitrogen nqcc's in equatorial and axial morpholine (chair) was made here on molecular structures given by MP2/6-311+G(2d,2p) optimization and, for the equatorial conformer, on the effective structure of Indris, et al. [1].   These are compared with the experimental nqcc's for equatorial morpholine [1] in Tables 1 - 3.  Calculated nqcc's for the axial conformer are given in Tables 4 and 5.  MP2/6-311+G(2d,2p) structure parameters are shown in Table 6, rotational constants in Table 7.


 








In Tables 1 - 4, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia b-axis, these are perpendicular to the molecular symmetry plane.  (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

 








RMS is the root mean square difference between calculated and experimental nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation of the models for calculation of nitrogen and deuterium nqcc's.

 








 








   







Table 1.  Nitrogen nqcc's in Morpholine, equatorial (MHz).  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   










Calc.
Expt. [2]
   







14N Xaa
2.210
2.1491(24)


Xbb
2.788
2.7966(25)


Xcc - 4.998 - 4.9457(24)


|Xac|
0.735



 







RMS
0.046 (1.4 %)
 


RSD
0.030 (1.3 %)



 







Xxx
2.284




Xyy
2.788



  Xzz - 5.072



  ETA
0.099




z,a
84.24




a,NH
15.44




z,NH
68.79




z,NC
72.33



 







 








 








   







Table 2.  Nitrogen and Deuterium nqcc's in N-Deutero-Morpholine, equatorial.  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   










Calc.
Expt. [2]
   







14N (MHz) Xaa
2.210
2.166(6)


Xbb
2.788
2.787(4)


Xcc - 4.998 - 4.953(6)


|Xac|
0.732



 







RMS
0.037 (1.1 %)
 


RSD
0.030 (1.3 %)



 






 2H (kHz) Xaa
221.9
220(10)


Xbb - 102.2 - 108(6)

  Xcc - 119.7 - 112(11)

  |Xac|
  96.1



 







RMS
5.7 (3.9 %)




RSD
1.1 (0.86 %)



 






  Xxx - 144.9




Xyy - 102.2




Xzz
247.1




ETA - 0.173




z,a
14.68




a,ND
15.47




z,ND
  0.79



 







 








 








   







Table 3.  Nitrogen nqcc's in Morpholine, equatorial (MHz).  Calculation was made on the ro structure [1].
   










Calc.
Expt. [2]
   







14N Xaa
2.279
2.1491(24)


Xbb
2.746
2.7966(25)


Xcc - 5.025 - 4.9457(24)


|Xac|
0.364



 







RMS
0.092 (2.8 %)
 


RSD
0.030 (1.3 %)



 







Xxx
2.297




Xyy
2.746



  Xzz - 5.043



  ETA
0.089




z,a
92.85




a,NH
18.61




z,NH
68.55




z,NC
70.79



 







 








 








   







Table 4.  Nitrogen nqcc's in Morpholine, axial (MHz).  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   










Calc.
Expt.
   







14N Xaa - 3.550




Xbb
2.776




Xcc
0.774




|Xac|
0.656



 







RSD
0.030 (1.3 %)



 







Xxx
2.303




Xyy
2.776



  Xzz - 5.080



  ETA
0.093




z,a
152.93




a,NH
  83.70




z,NH
  69.22




z,NC
  70.94



 







 








 








   







Table 5.  Nitrogen and Deuterium nqcc's in N-Deutero-Morpholine, axial.  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   










Calc.
Expt.
   







14N (MHz) Xaa - 3.419




Xbb
2.776




Xcc
0.642




|Xac|
3.083



 







RSD
0.030 (1.3 %)



 






 2H (kHz) Xaa - 134.2




Xbb - 100.1



  Xcc
234.2



  |Xac|
  57.0



 







RSD
1.1 (0.86 %)



 






  Xxx - 142.8




Xyy - 100.1




Xzz
234.2




ETA - 0.176




z,a
81.40




a,ND
82.46




z,ND
  1.06



 







 








 








Energy:  For the MP2/6-311+G(2d,2p) optimized structures, Eeq < Eax by 1.04, 0.82, and 0.76 kcal/mol respectively at the MP2/6-311+G(2d,2p), B3PW91/6-311+G(df,pd), and B3LYP/6-31G(df,3p) levels of theory.

 







 
 


Table 6. Molecular structure parameters, MP2/6-311+G(2d,2p) ropt ( and degrees).
 




Equatorial Axial
Equatorial



C(1)N 1.4639 1.4661
NH 1.0102 1.0134
C(1)C(2) 1.5162 1.5202
C(2)O(3) 1.4266 1.4264
C(1)H(8) 1.0883 1.0888

C(1)H(9) 1.0970 1.0899
Axial C(2)H(10) 1.0937 1.0968

C(2)H(11) 1.0858 1.0869
C(5)NC(1) 109.89 109.97
NC(1)C(2) 108.14 112.67
C(1)C(2)O(3) 110.86 110.88
C(2)O(3)C(4) 110.08 110.26
NC(1)H(8) 109.26 109.12

NC(1)H(9) 112.50 107.64
Dihedral angles? C(1)C(2)H(10) 109.34 109.83
See Z-Matrix. C(1)C(2)H(11) 111.18 111.60



 








 














Table 7.  Morpholine.  Rotational Constants (MHz).  Normal Species.
 





  eq ropt eq Expt. [1] ax ropt  ax Expt.







A 4952.4 4924.9875(53) 4912.4

B 4651.0 4625.1166(53) 4608.0

C 2702.0 2684.2359(54) 2692.4


 








 








[1] O.Indris, W.Stahl, and U.Kretschmer, J.Mol.Spectrosc. 190,372(1998).

[2] J.-U.Grabow, H.Ehrlichmann, H.Dreizler, Z.Naturforsch. 44a,833(1989).

 








J.J.Sloan and R.Kewley, Can.J.Chem. 47,3453(1969): In Morpholine, eq. Xaa = 2.22(2) MHz, Xbb = 2.51(5) MHz, Xcc = -4.73(2) MHz, and in N-Deuteromorpholine, eq.  Xaa = 1.92(2) MHz, Xbb = 2.59(5) MHz, Xcc = -4.51(2) MHz.


 









 








Piperidine Pyridine Pyrrolidine Pyrrole


DimethylamineN-Methyl-Morpholine






 








 








Table of Contents




Molecules/Nitrogen




Molecules/Deuterium




 













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Last Modified 21 Feb 2006