CH2NH PDF


 





Nitrogen

Nuclear Quadrupole Coupling Constants


in Methylenimine


 







 
 
Calculation of the nitrogen nqcc's in methylenimine was made here on the molecular substitution structure of  Pearson and Lovas [2], on the "semi-experimental" equilibrium structure of Margulès et al. [3], and on ropt molecular structures given by MP/6-311+G(3df,3pd) and MP2/aug-cc-pVTZ optimizations.  These are compared with the experimental nqcc's of Krause et al. [1] and of Dore et al. [4] in Tables 1 - 4.  Molecular structure parameters are compared in Table 5. 
Calculation of the nqcc's was made also on structures optimized at the B3P86/ and MP2/6-311+G(3d,3p) levels of theory, and on the "semi-experimental" equilibrium structure of Margulès et al. [3].  These are compared with the experimental nqcc's in Tables 2 and 3.  Molecular structure parameters are compared in Table 4.
 
In Tables 1 - 4, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts x,y,z to the principal axes of the nqcc tensor.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the plane of the molecule.  Ø (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 average experimental nqcc).  RSD is the residual standard deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's.
 
 
   






Table 1.  14N nqcc's in CH2NH (MHz).  Calculation was made on the substitution structure of Pearson and Lovas [2].
   







Calc.
Expt. [1]
Expt. [4]
   





Xaa - 0.918 - 0.9131(16) - 0.9148(12)
Xbb - 2.662 - 2.6688(14) - 2.6665 *
Xcc 3.580 3.5819(21) 3.5813 *
|Xab| 2.519
 
RMS 0.005 (0.22 %) 0.003 (0.10 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 0.876
Xyy 3.580
Xzz - 4.456
ETA 0.607
Øz,a 54.5
Øa,bi 59.7
Øz,bi**   5.2
 
   
* Calculated here from experimental Xaa and Xbb - Xcc = 6.24772(17) MHz.
** The z-axis makes an angle of 5.2o with the external bisector ( 'bi' ) of the CNH angle.
 
 
   






Table 2.  14N nqcc's in CH2NH (MHz).  Calculation was made on the "semi-experimental" re molecular structure of Margulès, et al. [3].
   







Calc.
Expt. [1]
Expt. [4]
   





Xaa - 0.953 - 0.9131(16) - 0.9148(12)
Xbb - 2.664 - 2.6688(14) - 2.6665 *
Xcc 3.617 3.5819(21) 3.5813 *
|Xab| 2.563
 
RMS 0.031 (1.3 %) 0.030 (1.3 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 0.893
Xyy 3.617
Xzz - 4.510
ETA 0.604
Øz,a 54.23
Øa,bi 59.67
Øz,bi**   5.44
 
 
* Calculated here from experimental Xaa and Xbb - Xcc = 6.24772(17) MHz.
** The z-axis makes an angle of 5.2o with the external bisector ( 'bi' ) of the CNH angle.
 
 
   






Table 3.  14N nqcc's in CH2NH (MHz).  Calculation was made ropt = MP2/6-311+G(3df,3pd) optimized structure.
   







Calc.
Expt. [1]
Expt. [4]
   





Xaa - 0.942 - 0.9131(16) - 0.9148(12)
Xbb - 2.651 - 2.6688(14) - 2.6665 *
Xcc 3.594 3.5819(21) 3.5813 *
|Xab| 2.522
 
RMS 0.021 (0.87 %) 0.019 (0.78 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 0.866
Xyy 3.594
Xzz - 4.460
ETA 0.612
Øz,a 54.36
Øa,bi 59.46
Øz,bi**   5.10
 
 
* Calculated here from experimental Xaa and Xbb - Xcc = 6.24772(17) MHz.
** The z-axis makes an angle of 5.2o with the external bisector ( 'bi' ) of the CNH angle.
 
 
   






Table 4.  14N nqcc's in CH2NH (MHz).  Calculation was made ropt = MP2/aug-cc-pVTZ  optimized structure.
   







Calc.
Expt. [1]
Expt. [4]
   





Xaa - 0.933 - 0.9131(16) - 0.9148(12)
Xbb - 2.652 - 2.6688(14) - 2.6665 *
Xcc 3.585 3.5819(21) 3.5813 *
|Xab| 2.518
 
RMS 0.015 (0.64 %) 0.014 (0.55 %)
RSD 0.030 (1.3 %) 0.030 (1.3 %)
 
Xxx 0.869
Xyy 3.585
Xzz - 4.453
ETA 0.610
Øz,a 54.42
Øa,bi 59.44
Øz,bi**   5.02
 
 
* Calculated here from experimental Xaa and Xbb - Xcc = 6.24772(17) MHz.
** The z-axis makes an angle of 5.2o with the external bisector ( 'bi' ) of the CNH angle.
 
 
 
Table 4.   CH2NH  Molecular structure parameters (Å and degrees).  ropt(1) = MP2/6-311+G(3df,3pd) optimized structure, ropt(2) = MP2/aug-cc-pVTZ optimized structure.
 
ropt(1) ropt(2) rs [2] re [3]
CN 1.2747 1.2764 1.273 1.2709(1)
NH 1.0196 1.0205 1.021 1.0195(2)
CHt 1.0854 1.0857 1.09 1.0839(31)
CHc 1.0900 1.0902 1.09 1.0919(32)
HNC 109.98 109.95 110.4 110.348(37)
HtCHc 117.01 117.00 117.0
NCHc 124.43 124.48 125.1 123.72(43)
NCHt 118.56 118.52 119.25(45)
 
 
[1] H.Krause, D.H.Sutter, and M.H.Palmer, Z.Naturforsch. 44a,1063(1989).
[2] R.Pearson Jr and F.J.Lovas, J.Chem.Phys. 66,4149(1977).
[3] L.Margulès, J.Demaison, P.B.Sreeja, and J-C.Guillemin, J.Mol.Spectrosc. 238,234(2006).
[4] L.Dore, L.Bizzocchi, C. Delgi Esposti, and J. Gauss, J.Mol.Spectrosc. 263,44(2010).
 
Related ...
H.Krause and D.H.Sutter, Z.Naturforsch. 46a,785(1991).
R.D.Brown, P.D.Godfrey, and D.A.Winkler, Aust.J.Chem. 35,667(1982).
R.Pearson Jr and F.J.Lovas, Chem.Phys.Lett. 15,65(1972).

 








 







CF2NH (CH3)2NH CH2NOH CF2NF
trans-Ethanimine cis-Ethanimine Ethylenimine
trans-syn-Propenimine trans-anti-Propenimine
 

 








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Molecules/Nitrogen
 

 













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Last Modified 2 July 2010