CH3CH2CH2CN































 








Nitrogen

Nuclear Quadrupole Coupling Constants


in gauche-1-Cyanopropane


 








 








 








Calculation of the nitrogen nqcc tensor in the gauche conformer of 1-cyanopropane (aka gauche butyronitrile) was made here on an approximate equilibrium molecular structure given by MP2/aug-cc-pVTZ optimization with empirically corrected bond lengths. These are compared in Table 1 with the experimental nqcc's of Dewberry et al. [1].  Structure parameters are given in Table 2, rotational constants in Table 3, dipole moments and centrifugal distortion constants in Table 4.

 








In Table 1, subscripts a,b,c refer to the principal axes of the inertia tensor, subscripts x,y,z to the principal axes of the nqcc tensor.  Ø (degrees) is the angle between its subscripted parameters. ETA = (Xxx - Xyy)/Xzz.

RMS is the root mean square difference between calculated and experimental nqcc's (percentage of average experimental nqcc).  RSD is the residual standard deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's, which may be taken as as estimate of the uncertainty in the calculated nqcc's.

 








 








   






Table 1. Nitrogen nqcc's in gauche-1-Cyanopropane (MHz).
   









Calc.
Expt. [1]
   






14N Xaa - 1.658 - 1.6825(27)


Xbb - 0.270 - 0.2490(27)


Xcc
1.928
1.9315(26)


Xab - 3.012 - 3.12(30)


Xac - 0.794 - 0.70(17)


Xbc - 0.560 - 0.56(10) *

 







RMS
0.019 (1.5 %)




RSD
0.030 (1.3 %)



 







Xxx
2.164
2.23(29)  **


Xyy
2.045
2.06(4)


Xzz - 4.208 - 4.30(29)


ETA - 0.028 - 0.041(7)


Øz,CN
  0.42



 






   








* Calculated value.  Estimated uncertainity is the average of differences between calculated and experimental values of Xab and Xac.

** Calculated here using Kisiel's QDIAG.f program.

 








 









 

Table 2.  gauche-1-Cyanopropane.  Heavy atom molecular structure parameters (Å and degrees).  Complete structure, including dihedral angles, is given here in Z-matrix format.
   



C(11)N 1.1562

C(1)C(11) 1.4613

C(1)C(11)N 178.31

 

C(1)C(2) 1.5300

C(2)C(3) 1.5199

C(11)C(1)C(2) 111.51

C(1)C(2)C(3) 112.23





 








 








 


Table 3.  gauche-1-Cyanopropane.  Rotational Constants (MHz).
 




Calc. ropt    Expt. [1]





A 10 042.5 10 060.41082(99)

B   3 336.2   3 267.66075(32)

C   2 751.6   2 705.45767(29)


 








 








 




Table 4.  gauche-1-Cyanopropane.  Dipole Moments [3] and Quartic Centrifugal Distortion Constants [2].  Calc = B3LYP/cc-pVTZ.









Calc.
Expt. [2,3]







|µa| /D
3.38
3.272(37)

|µb| /D
2.15
2.139(30)

|µc| /D
0.45
  -------

 




DJ /kHz
3.08
3.195064(207)

DJK /kHz -
 21.3
 -
 18.26470(117)

DK /kHz
71.6
60.235(6)

d1 /Hz -
 987.
 -
 1037.470(55)

d2 /Hz -
 64.7
 -
 77.1864(183)


 








 








[1] C.T.Dewberry, G.S.Grubbs II, A.Raphelt, and S.A.Cooke, 64th Ohio State University Symposium on Molecular Spectroscopy, June 22-26, 2009.

[2] G.Wlodarczak, L.Martinache, J.Demaison, K.-M.Marstokk, and H.Møllendal, J.Mol.Spectrosc. 127,178(1988).

[3] A.Belloche, R.T.Garrod, H.S.P.Müller, K.M.Menten, C.Comito, and P.Schilke, A & A 499,215(2009).

 








K.Vormann and H.Dreizler, Z.Naturforsch. 43a,338(1988):  Xaa = -1.683(4) MHz,  Xbb = -0.252(5) MHz,  Xcc = 1.935(5) MHz.

J.Demaison and H.Dreizler, Z.Naturforsch. 37a,199(1982):  Xaa = -1.672(22) MHz,  Xbb = -0.263(22) MHz,  Xcc = 1.935(20) MHz.

 








 








n-Butyl Cyanide, anti-anti 1-Cyanopropane, trans

n-Butyl Cyanide, anti-gauche CH3CN


n-Butyl Cyanide, gauche-anti CH3CH2CN

 








 








Table of Contents




Molecules/Nitrogen




 








 













g1CNpropane.html






Last Modified 23 Aug 2010