C5H10N2O































 









Nitrogen


Nuclear Quadrupole Coupling Constants

in 1,3-Dimethyl-2-Imidazolidione


 








 









Molecular conformation and 14N nuclear quadrupole coupling constants in 1,3-dimethyl-2-imidazolidione were determined by Vigorito, et al. [1].

Calculation of the 14N nuclear quadrupole coupling constants was made here on an MP2/6-311++G(d,p) opimized molecular structure reported in Ref. [1], and on another derived here by MP2/6-311+G(3d,3p) optimization.


 








Calculated and experimental nqcc's are compared in Table 1.  Structure parameters in z-matrix format are given in Table 2, rotational constants in Table 3.


In Table 1, 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.  (degrees) is angle between z- and c- axes.  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 1,3-Dimethyl-2-imidazolidione (MHz).  Calculation was made on the ropt(1) = MP2/6-311++G(d,p) and ropt(2) = MP2/6-311+G(3d,3p) structures.

   










Calc /ropt(1)
Calc /ropt(2)
Expt [1]

   








Xaa
2.300

2.288

2.14(14)


Xbb
2.438

2.446

2.56(10)


Xcc -
4.738
-
4.734
-
4.70(10)


Xab +/-
0.135
+/-
0.134




Xac
0.136

0.138




Xbc -/+
0.456
-/+
0.416




 







RMS

0.118 (3.8 %)

0.110 (3.5 %)



RSD
0.030 (1.3 %)

0.030 (1.3 %)



 








Xxx
2.234

2.226




Xyy
2.536

2.535




Xzz -
4.770
-
4.761




ETA

0.0632

0.0650




z,c

3.8

3.5




 









 








 









 



Table 2.  1,3-Dimethyl-2-imidazolidione:  Structure parameters,  ropt(1) and ropt(2) ( and degrees). 





 O
 C,1,B1
 N,2,B2,1,A1
 N,2,B3,1,A2,3,D1,0
 C,3,B4,2,A3,1,D2,0
 C,4,B5,2,A4,1,D3,0
 H,5,B6,3,A5,2,D4,0
 H,6,B7,4,A6,2,D5,0
 H,5,B8,3,A7,2,D6,0
 H,6,B9,4,A8,2,D7,0
 C,3,B10,2,A9,1,D8,0
 C,4,B11,2,A10,1,D9,0
 H,11,B12,3,A11,2,D10,0
 H,12,B13,4,A12,2,D11,0
 H,11,B14,3,A13,2,D12,0
 H,12,B15,4,A14,2,D13,0
 H,11,B16,3,A15,2,D14,0
 H,12,B17,4,A16,2,D15,0


      ropt(1)       ropt(2)




 B1=1.22080009
 B2=1.39310133
 B3=1.39310133
 B4=1.45411835
 B5=1.45411835
 B6=1.10207972
 B7=1.10207972
 B8=1.09302508
 B9=1.09302508
 B10=1.45028672
 B11=1.45028672
 B12=1.09004367
 B13=1.09004367
 B14=1.10003545
 B15=1.10003545
 B16=1.09264532
 B17=1.09264532
 A1=126.28804500
 A2=126.28804500
 A3=109.12987381
 A4=109.12987381
 A5=111.03788705
 A6=111.03788705
 A7=111.52798073
 A8=111.52798073
 A9=118.68964962
 A10=118.68964962
 A11=108.26615601
 A12=108.26615601
 A13=111.48819480
 A14=111.48819480
 A15=109.57240039
 A16=109.57240039
 D1=-180.
 D2=168.17481779
 D3=168.17481779
 D4=-88.57827681
 D5=-88.57827681
 D6=149.17358123
 D7=149.17358123
 D8=26.03101788
 D9=26.03101788
 D10=-38.20348554
 D11=-38.20348554
 D12=81.62214705
 D13=81.62214705
 D14=-157.48274650
 D15=-157.48274650
 B1=1.22104035
 B2=1.38946743
 B3=1.38946743
 B4=1.45232915
 B5=1.45232915
 B6=1.09655484
 B7=1.09655484
 B8=1.0880191
 B9=1.0880191
 B10=1.44734849
 B11=1.44734849
 B12=1.08602678
 B13=1.08602678
 B14=1.09477797
 B15=1.09477797
 B16=1.08804203
 B17=1.08804203
 A1=126.26806375
 A2=126.26806375
 A3=109.29419808
 A4=109.29419808
 A5=110.89423864
 A6=110.89423864
 A7=111.55455766
 A8=111.55455766
 A9=118.74744738
 A10=118.74744738
 A11=108.20479406
 A12=108.20479406
 A13=111.38826932
 A14=111.38826932
 A15=109.82420364
 A16=109.82420364
 D1=180.
 D2=168.43761728
 D3=168.43761728
 D4=-89.47787724
 D5=-89.47787724
 D6=148.53156374
 D7=148.53156374
 D8=26.13643993
 D9=26.13643993
 D10=-35.32512903
 D11=-35.32512903
 D12=84.45312914
 D13=84.45312914
 D14=-154.68170399
 D15=-154.68170399







 








 






Table 3.  1,3-Dimethyl-2-imidazolidione: Rotational Constants (MHz).

 






Calc /ropt(1) Calc /ropt(2)   Expt [1]


 





 A
    3356.
   3364.
3358.889(1)


 B
    2029.
   2037.
2024.311(1)


 C
    1321.
   1325.
1317.033(2)










 








 









[1] A.Vigorito, L.Paoloni, C.Calabrese, L.Evangelisti, L.B.Favero, S.Melandri, and A.Maris, J.Mol.Spectrosc. 342,38(2017).


 









 









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Molecules/Nitrogen




 








 













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Last Modified 23 April 2017