(CH3)2NH PDF



 








Nitrogen


Nuclear Quadrupole Coupling Constants


in Dimethylamine


 







 
 
Calculation of the nitrogen nqcc's in dimethylamine was made on the substitution structure of Wollrab and Laurie [1].  These are compared in Table 1 with the experimental nqcc's [1].  In Tables 2 and 3, nqcc's calculated on structures given by mPW1PW91 and MP2 optimizations each in conjunction with 6-311++G(3df,3pd) and aug-cc-pVTZ bases are compared with the experimental nqcc's.  Structure parameters are given in Table 4.
 
In Tables 1 - 3, 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 nqcc's.
 
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 x-axis is chosen coincident with the inertia a-axis, these are perpendicular to the molecular symmetry plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.
 
 
   







Table 1. Nitrogen nqcc's in (CH3)2NH (MHz).  Calculation was made on the substitution structure [1].
   










Calc.
Expt. [1]
   






14N Xaa 2.948 3.04(12)
Xbb 0.793 0.93(12)
Xcc - 3.742 - 3.97(24)
|Xbc| 2.981 2.48(40)
 
RMS 0.16 (6.1 %)
RSD 0.030 (1.3 %)
 
Xxx 2.948 3.04(12)
Xyy 2.271 2.01(50)
Xzz - 5.220 - 5.05(40)
ETA - 0.130 - 0.2
Øz,c 26.4
Øc,NH 42.8
Øz,NH 69.2
 
 
 
   







Table 2.  14N nqcc's in (CH3)2NH (MHz).  Calculation was made on the MP2/ and mPW1PW91/6-311+G(3d,3p) optimized structures.
   








 MP2
  mPW1PW91
Expt. [1]
   






Xaa 2.935 2.983 3.04(12)
Xbb 0.809 0.955 0.93(12)
Xcc - 3.744 - 3.938 - 3.97(24)
|Xbc| 2.985 2.956 2.48(40)
 
RMS 0.16 (6.0 %) 0.040 (1.5 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 2.935 2.983 3.04(12)
Xyy 2.289 2.345 2.01(50)
Xzz - 5.222 - 5.328 - 5.05(40)
ETA - 0.124 - 0.120 - 0.2
Øz,c 26.34 25.19
Øc,NH 42.88 45.29
Øz,NH 69.22
70.48
 
 
 
   







Table 3.  14N nqcc's in (CH3)2NH (MHz).  Calculation was made on the MP2/ and mPW1PW91/aug-cc-pVTZ optimized structures.
   








 MP2
  mPW1PW91
Expt. [1]
   






Xaa 2.934 2.988 3.04(12)
Xbb 0.798 0.967 0.93(12)
Xcc - 3.732 - 3.956 - 3.97(24)
|Xbc| 2.987 2.949 2.48(40)
 
RMS 0.22 (8.2 %) 0.038 (1.4 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 2.934 2.988 3.04(12)
Xyy 2.281 2.347 2.01(50)
Xzz - 5.215 - 5.336 - 5.05(40)
ETA - 0.125 - 0.120 - 0.2
Øz,c 26.42 25.08
Øc,NH 42.67 45.45
Øz,NH 69.08
70.52
 
 
 
Table 4.  Dimethylamine.  Molecular structure parameters.  Substitution and ab initio.  (Å and degrees).  For dihedral angles, see Z-Matrix.
  rs [1]
HN 1.019(7)
NC 1.462(5)
CH(5) 1.084(5)
CH(7) 1.098(4)
CH(9) 1.098(4)
CNC 112.2(2)
HNC 108.9(3)
NCH(5) 109.7(3)
NCH(7) 108.2(3)
NCH(9) 113.8(3)
Ab initio Structures.  Z-Matrix.
 
  6-311++G(3df,3pd)   aug-cc-pVTZ
MP2 mPW1PW91 MP2 mPW1PW91
HN 1.0114 1.0093 1.0123 1.0091
NC 1.4540 1.4458 1.4562 1.4463
CH(5) 1.0877 1.0894 1.0884 1.0896
CH(7) 1.0894 1.0914 1.0898 1.0916
CH(9) 1.0982 1.1009 1.0988 1.1010
CNC 111.57 113.03 111.38 113.06
HNC 109.18 109.90 109.14 109.97
NCH(5) 109.84 109.95 109.90 109.92
NCH(7) 108.99 109.45 108.93 109.42
NCH(9) 113.45 113.91 113.39 113.93
 
 
[1] J.E.Wollrab and V.W.Laurie, J.Chem.Phys. 48,5058(1968).

 








 








CH2NH CF2NH Ethylenimine Pyrrolidine
trans-Ethanimine cis-Ethanimine Piperidine
trans-syn-Propenimine trans-anti-Propenimine Morpholine
 

 








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Molecules/Nitrogen
 

 













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Last Modified 3 Jan 2006