CH3-SiHF-N=C=O











































Nitrogen


Nuclear Quadrupole Coupling Constants


in Methylfluoroisocyanate Silane


 








 








 


 





The microwave spectrum of methylfluoroisocyanate silane was observed and assigned by Seifert, Guirgis, et al. [1,2].


 








Calculation of the 14N nqcc tensor was made here on ropt molecular structures given by HF/6-31G(3d,3p) and HF/6-311G(3d,3p) optimization, and on a MP3/aug-cc-pVTZ optimized structure derived by Guirgis et al. [2].  These calculated nqcc's are compared with the experimental values [1,2] in Table 1.  Structure parameters  in Z-matrix format for the HF optimizations are compared in Table 2, rotational constants and dipole moments in Table 3, and centrifugal distortion constants in Table 4.  For the MP3 optimization, see Ref. [2].


 








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.  is the angle between its subcripted parameters.


RMS is root mean square difference between calculated and experimental 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 CH3-SiHF-N=C=O (MHz).  Calculation was made on (1) HF/6-31G(3d,3p), (2) HF/6-311G(3d,3p), and (3) MP3/aug-cc-pVTZ ropt structures.
 












Calc (1)

Calc (2)

Calc (3)
Expt [1,2] *

 










Xaa
1.726

1.737

1.811

1.770(7)


Xbb -
0.855
-
0.857
-
0.891
-
0.839(36)


Xcc -
0.871
-
0.880
-
0.919
-
0.931(36)


Xab
0.139

0.121

0.149




Xac -
0.408
-
0.250
-
0.254




Xbc -
0.033
-
0.004

0.002















RMS

0.044 (3.7 %)

0.037 (3.1 %)

0.039 (3.3 %)




RSD
0.030 (1.3 %)
0.030 (1.3 %)
0.030 (1.3 %)














Xxx -
0.861
-
0.858
-
0.894




Xyy -
0.935 -
0.908
-
0.948




Xzz
1.796

1.766

1.842




ETA
0.0413

0.0285

0.0291




z,N=C
6.95

8.33
7.18
















 








* Xaa, Xbb, Xcc derived here from experimental 1.5Xaa = 2.655(11) and 0.25(Xbb - Xcc) = 0.023(18) MHz.











 
 


Table 2. CH3-SiHF-N=C=O.  HF/6-31G(3d,3p) and HF/6-311G(3d,3p) ropt structure parameters ( and degrees).





 C
 Si,1,B1
 N,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 O,4,B4,3,A3,2,D2,0
 H,2,B5,3,A4,4,D3,0
 F,2,B6,3,A5,4,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



HF/6-31G(3d,3p)
HF/6-311G(3d,3p)





 B1=1.8474159
 B2=1.70124874
 B3=1.18327343
 B4=1.14431429
 B5=1.46291508
 B6=1.5844807
 B7=1.08643881
 B8=1.08656174
 B9=1.08608598
 A1=110.11742251
 A2=157.22143802
 A3=177.80777346
 A4=108.6715672
 A5=107.88320335
 A6=110.70612224
 A7=110.51918747
 A8=111.0796777
 D1=147.37312784
 D2=-179.27358425
 D3=-88.36014533
 D4=27.88917231
 D5=-179.12477079
 D6=61.13153467
 D7=-58.86481063
 B1=1.84616011
 B2=1.7032079
 B3=1.18108404
 B4=1.14017693
 B5=1.46447886
 B6=1.58238689
 B7=1.08405763
 B8=1.08443362
 B9=1.08378141
 A1=109.85429306
 A2=155.04342237
 A3=177.6985679
 A4=109.21623096
 A5=107.66011147
 A6=110.71229712
 A7=110.21230887
 A8=110.9222252
 D1=-174.71678886
 D2=176.30460511
 D3=-50.07439864
 D4=66.02908308
 D5=-178.630018
 D6=61.63761453
 D7=-58.19207679








 








 



Table 3. CH3-SiHF-N=C=O.  Rotational Constants (MHz) and Dipole Moments (D).  (1) HF/6-31G(3d,3p) and (2) HF/6-311G(3d,3p) ropt structures.







Calc (1)
Calc (2)   Expt [1]






A
6163.7
6340.3
6301.415(45)

B
1565.4
1548.0
1535.078(39)

C
1342.0
1320.3
1310.485(39)

|a|
 2.05
 1.93


|b|  1.40
 1.44


|c|  0.52
 0.61



 








 









 




Table 4. CH3-SiHF-N=C=O.  Quartic Centrifugal Distortion Constants (kHz).  Calc = B3LYP/cc-pVTZ









Calc

 Expt [1]







Delta_J

0.566

0.742(33)

Delta_JK
23.7

41.50(14)

Delta_K
1.06
-
25.39(10)

delta_J
0.0184

0.067(13)

delta_K
12.6

25.6(19)








 









 









[1] N.A.Seifert, S.Lobsiger, B.H.Pate, G.A.Guirgis, J.S.Overby, and J.R.Durig, Abstract RC12, 68th International Symposium on Molecular Spectroscopy, 2013.


[2] G.A.Guirgis, J.S.Overby, T.J.Barker, M.H.Palmer, B.H.Pate, and N.A.Seifert, J.Phys.Chem. A, 119(4),652(2015).


 








 








Methyldifluoroisocyanate Silane
CH3CH2N=C=O
Acetylisocyanate
HNCO


Difluoroisocyanato Silane
Vinylisocyanate
tert-Butylisocyanate
ClNCO












 








Table of Contents




Molecules/Nitrogen




 








 













CH3SiHFNCO.html






Last Modified 9 Dec 2016