(CH3)3C-N=C=O





 





 






























Nitrogen


Nuclear Quadrupole Coupling Constants


in  tert-Butyl isocyanate


 








 








 








The complete 14N nqcc tensor in tert-butyl isocyanate was determined by Grabow et al. [1].


 









Calculation of the 14N nqcc tensor was made here on ropt molecular structures given by  B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd) optimization.  Calculated and experimental nqcc's are compared in Table 1.  Structure parameters are given in Table 2; rotational constants and electric dipole moments 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.  The nqcc x-axis is chosen coincident with the inertia b-axis, these are perpendicular to the molecular plane.  (degrees) is the angle between its subscripted parameters.  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 nitrogen efg's/nqcc's.

 








 








   








Table 1.  14N nqcc's in tert-Butyl isocyanate (MHz).  Calculation was made on molecular structures given by (1) B3LYP/6-311+G(3df,3pd) and (2) MP2/6-311+G(3df,3pd) optimization.
   










Calc. (1)

Calc. (2)
Expt. [1]

   








Xaa
2.681

2.676

2.6376(4)


Xbb -
1.492
-
1.534
-
1.4935(7)


Xcc -
1.189
-
1.142
-
1.1441(7)


|Xac|
0.203

0.103

0.1731(15)











RMS

0.036 (2.0 %)

0.032 (1.8 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx -
1.492
-
1.534
-
1.4935


Xyy -
1.200
-
1.145
-
1.1520


Xzz
2.692

2.679

2.6455


ETA -
0.109
-
0.145




z,a
  2.99

  1.55

2.615


a,C(2)N

22.97

25.12




z,C(2)N

19.98

23.57




 








 








 







 
 

Table 2.  tert-Butyl isocyanate.  Optimized molecular structure parameters, ropt ( and degrees).
 

B3LYP/6-311+G(3df,3pd)  and  MP2/6-311+G(3df,3pd)
 




 C
 C,1,B1
 N,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 O,4,B4,3,A3,2,D2,0
 C,2,B5,1,A4,3,D3,0
 C,2,B6,1,A5,3,D4,0
 H,1,B7,2,A6,3,D5,0
 H,1,B8,2,A7,3,D6,0
 H,1,B9,2,A8,3,D7,0
 H,6,B10,2,A9,1,D8,0
 H,6,B11,2,A10,1,D9,0
 H,6,B12,2,A11,1,D10,0
 H,7,B13,2,A12,1,D11,0
 H,7,B14,2,A13,1,D12,0
 H,7,B15,2,A14,1,D13,0


         B3LYP
        MP2


   B1=1.53149082
   B2=1.46682326
   B3=1.19770649
   B4=1.17265997
   B5=1.53414376
   B6=1.53414376
   B7=1.08990392
   B8=1.08939699
   B9=1.08939699
   B10=1.09036621
   B11=1.08935385
   B12=1.09026164
   B13=1.08935385
   B14=1.09036621
   B15=1.09026164
   A1=107.15460652
   A2=139.13735300
   A3=173.96371396
   A4=110.44392464
   A5=110.44392464
   A6=110.25013180
   A7=110.60998552
   A8=110.60998552
   A9=110.15970391
   A10=110.64953188
   A11=110.84091584
   A12=110.64953188
   A13=110.15970391
   A14=110.84091584
   D1=180.
   D2=180.
   D3=-118.61394644
   D4=118.61394644
   D5=180.
   D6=59.94041612
   D7=-59.94041612
   D8=-60.65587354
   D9=59.21867776
   D10=179.57484832
   D11=-59.21867776
   D12=60.65587354
   D13=-179.57484832
 B1=1.52214397
 B2=1.4588154
 B3=1.21149214
 B4=1.1788562
 B5=1.52455771
 B6=1.52455771
 B7=1.08940094
 B8=1.08874946
 B9=1.08874946
 B10=1.0898967
 B11=1.08889262
 B12=1.08989552
 B13=1.08889262
 B14=1.0898967
 B15=1.08989552
 A1=107.0548629
 A2=135.48317605
 A3=173.01915046
 A4=110.53471892
 A5=110.53471892
 A6=109.92809237
 A7=110.3173426
 A8=110.3173426
 A9=109.95988415
 A10=110.33002408
 A11=110.46832715
 A12=110.33002408
 A13=109.95988415
 A14=110.46832715
 D1=180.
 D2=180.
 D3=-118.54056905
 D4=118.54056905
 D5=180.
 D6=59.96931595
 D7=-59.96931595
 D8=-60.64731314
 D9=59.31746731
 D10=179.51617279
 D11=-59.31746731
 D12=60.64731314
 D13=-179.51617279





 














Table 3.  tert-Butyl isocyanate.  Rotational Constants (MHz) and Dipole Moments * (D).







ropt(1) = B3LYP/6-311+G(3df,3pd) optimization.

ropt(2) = MP2/6-311+G(3df,3pd) optimization.








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








A
4551.1
4611.1
4572.6 (assumed)

B
1608.6
1631.6
1632.948(15)


C
1605.5
1628.1
1630.493(14)








|a| 3.23
3.08



|c| 0.70
0.76



 





* B3PW91/6-311+G(df,pd) dipole moment calculation on ropt structure.













 








[1] J.-U.Grabow, N.Heineking, and W.Stahl, J.Mol.Spectrosc. 154,129(1992).


 








 








HNCO
ClNCO
BrNCO
INCO


Difluoroisocyanato Silane
Ethylisocyanate


Methyldifluoroisocyanate Silane





 








 








Table of Contents




Molecules/Nitrogen




 








 













CH33CNCO.html






Last Modified 24 Nov 2013