CH3-C(H)NC-CH3






















 





 








Nitrogen

Nuclear Quadrupole Coupling Constants


in Isopropyl Isocyanide


 








 








 








Calculation of the nitrogen nqcc's in isopropyl isocyanide was made on molecular structures obtained by B3P86/6-31G(3d,3p) and mPW1PW91/6-31G(3d,3p) optimization.  These are compared in Table 1 with the experimental nqcc's of Krüger and Dreizler [1].  Structure parameters 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.  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 Isopropyl Isocyanide (MHz).  Calculation was made on (1) B3P86/6-31G(3d,3p) and (2) mPW1PW91/6-31G(3d,3p) optimized structures.
   









Calc (1)
Calc (2)
Expt. [1]
   







Xaa
0.255
0.249
0.1792(31)

Xbb - 0.159 - 0.155 - 0.1400(15)

Xcc -
 0.096 -
 0.094 - 0.0390(15)

|Xac|
0.094
0.092



 







RMS
0.056 (47 %)
0.052 (44 %)



RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx -
 0.120 -
 0.117



Xyy -
 0.159 -
 0.155



Xzz
0.279
0.272



ETA
0.139
0.142



Øz,a
14.12
14.10



Øa,NC
12.94
12.96



Øz,NC
  1.18
  1.14



 








 








 

Table 2.  Molecular structure parameters: B3P86/6-31G(3d,3p) and mPW1PW91/6-31G(3d,3p) opt structures (Å and degrees).
 


 C
 N,1,B1
 C,2,B2,1,A1
 H,3,B3,2,A2,1,D1,0
 C,3,B4,2,A3,1,D2,0
 C,3,B5,2,A4,1,D3,0
 H,5,B6,3,A5,2,D4,0
 H,5,B7,3,A6,2,D5,0
 H,5,B8,3,A7,2,D6,0
 H,6,B9,3,A8,2,D7,0
 H,6,B10,3,A9,2,D8,0
 H,6,B11,3,A10,2,D9,0




       B3P86
   mPW1PW91




 B1=1.17089522
 B2=1.4281343
 B3=1.09601816
 B4=1.52507683
 B5=1.52507683
 B6=1.09239041
 B7=1.09124024
 B8=1.09247493
 B9=1.09239041
 B10=1.09247493
 B11=1.09124024
 A1=179.02031981
 A2=106.34442585
 A3=109.81818888
 A4=109.81818888
 A5=109.71391433
 A6=110.9791956
 A7=110.46000915
 A8=109.71391433
 A9=110.46000915
 A10=110.9791956
 D1=180.
 D2=-62.2058063
 D3=62.2058063
 D4=-177.12912274
 D5=-57.12100531
 D6=63.24803258
 D7=177.12912274
 D8=-63.24803258
 D9=57.12100531
  B1=1.16940129
 B2=1.42762393
 B3=1.09512949
 B4=1.52503714
 B5=1.52503714
 B6=1.09165239
 B7=1.09056196
 B8=1.09170895
 B9=1.09165239
 B10=1.09170895
 B11=1.09056196
 A1=179.00549269
 A2=106.34335845
 A3=109.80464223
 A4=109.80464223
 A5=109.72306514
 A6=110.95167611
 A7=110.48423976
 A8=109.72306514
 A9=110.48423976
 A10=110.95167611
 D1=180.
 D2=-62.22006799
 D3=62.22006799
 D4=-177.15168977
 D5=-57.15974032
 D6=63.19437497
 D7=177.15168977
 D8=-63.19437497
 D9=57.15974032





 













Table 3.  Rotational Constants; B3P86/6-31G(3d,3p), mPW1PW91/6-31G(3d,3p), and experimental (MHz).







B3P86
 mPW1PW91      Expt [1]






A
  7996.
      7995.
 7963.0888(28)

B
  4324.
      4330.
 4316.7588(21)

C
  3094.
      3097.
 3088.8102(21)



 








 








[1] M.Krüger and H.Dreizler, Z.Naturforsch. 47a,1067(1992).

 








 








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Last Modified 13 Feb 2016