CH2CHNC












 








Nitrogen

Nuclear Quadrupole Coupling Constants


in Vinyl Isocyanide


 








 








 








Calculation of the nitrogen nqcc's in vinyl isocyanide was made on a structure obtained by B3P86/6-31G(3d,3p) optimization, and on the heavy atom substitution structure of Chang et al. [1].  These are compared in Table 1 with the experimental nqcc's of Bestman and Dreizler [2].  Structure parameters are given in Table 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.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular plane.  Ø (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 (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 efg's/nqcc's.

 








 








   







Table 1.  14N nqcc's in CH2CHNC (MHz).  Calculation was made on (1) B3P86/6-31G(3d,3p) optimized structure, and (2) the substitution structure of Chang et al. [1]
   









Calc (1)
Calc (2)
Expt. [2]
   







Xaa
0.259
0.270
0.258(5)

Xbb - 0.294 - 0.301 - 0.258(6)

Xcc
0.035
0.031 - 0.000(6)

|Xab|
0.317
0.316



 







RMS
0.029 (17 %)
0.031 (18 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx -
 0.435
 -
 0.442



Xyy
0.035
0.031



Xzz
0.403
0.411



ETA - 1.166 - 1.151



Øz,a
24.46
23.97



Øa,NC
15.06
15.72



Øz,NC
  9.40
  8.25



 








 








 


Table 2.  Molecular structure parameters: ropt = B3P86/6-31G(3d,3p); and heavy atom rs [1] with CH geometry given by partial optimization at MP2/6-31G(d,p) level where r(CH) = 1.001 x MP2/6-31G(d,p) optimized bond length [3] (Å and degrees).
 




  ropt   rs





CN 1.1755 1.174(6)

NC(1) 1.3746 1.379(6)

C(1)=C(2) 1.3296 1.338(4)

C(1)H 1.0850 1.082

C(2)Hc 1.0833 1.080

C(2)Ht 1.0824 1.079

CNC 177.59 178.2(12)

NCH 114.27 114.68

NC=C 123.13 122.5(7)

C(1)=C(2)Ht 119.75 119.77

C(1)=C(2)Hc 121.65 121.47


 








 








[1] Te-an Chang, M.D.Harmony, and S.W.Staley, J.Mol.Struct. 190,17(1988).

[2] G.Bestmann and H.Dreizler, Z.Naturforsch. 37a,58(1982).

[3] J.Demaison and G.Wlodarczak, Struct.Chem. 5,57(1994).

 








 








CH3CH2NC CH3NC CF3NC HCCNC

(CH3)3CNC C6H5NC CNCN HNC

 








 








Table of Contents




Molecules/Nitrogen




 








 













CH2CHNC.html






Last Modified 13 Oct 2009