CH3CH=C=C(H)CN























 








Nitrogen

Nuclear Quadrupole Coupling Constants


in 4-Methylcyanoallene


 
(2,3-Pentadienylnitrile)



 








 








The microwave spectrum of 4-methylcyanoallene was assigned by Carles et al. [1].  However, hyperfine structure due to the 14N quadrupole interaction was not resolved.











Calculation of the nitrogen nqcc tensor in 4-methylcyanoallene was made here on molecular structures given by MP2/6-311+G(3df,3pd) and MP2/aug-cc-pVTZ optimization, each with approximate equilibrium C=C, C-C, and CN bond lengths (see links).  These nqcc's are given in Table 1.  Structure parameters are given in Z-matrix format in Table 2,  rotational constants in Table 3.

 








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.  ETA = (Xxx - Xyy)/Xzz.  Øz,CN (degrees) is the angle between the z-principal axis and the CN bond axis.

RSD is the residual standard deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's.

 








 








 








Table 1. Nitrogen nqcc's in 4-Methylcyanoallene (MHz).  Calculation was made here on molecular structures given by (1) MP2/6-311+G(3df,3pd) and (2) MP2/aug-cc-pVTZ optimization, each with approximate re bond lengths.
 










Calc (1)
Calc (2)
Expt
 








Xaa -
 1.806
 -
 1.818



Xbb
0.006
0.018



Xcc
1.799
1.800



Xab -
 2.971
 -
 2.967



Xac
0.912
0.913



Xbc
0.425
0.424












RSD
0.030 (1.3 %)
0.030 (1.3 %)












Xxx
1.852
1.852



Xyy
2.317
2.317



Xzz -
 4.169
 -
 4.169



ETA
0.112
0.112



Øz,CN
0.52
0.55












   








 








 



Table 2.  4-Methylcyanoallene.  Optimized structure parameters (Å and degrees).  Corrected approximate re bond lengths are given in parentheses.






 C
 H,1,B1
 C,1,B2,2,A1
 C,3,B3,2,A2,1,D1,0
 H,4,B4,3,A3,2,D2,0
 C,4,B5,3,A4,5,D3,0
 H,6,B6,4,A5,3,D4,0
 H,6,B7,4,A6,3,D5,0
 H,6,B8,4,A7,3,D6,0
 C,1,B9,3,A8,6,D7,0
 N,10,B10,3,A9,1,D8,0






MP2/6-311+G(3df,3pd)
 MP2/aug-cc-pVTZ






 B1=1.08312993
 B2=1.31612444      (1.3137)
 B3=1.3053312        (1.3032)
 B4=1.08554009
 B5=1.50231129      (1.5011)
 B6=1.08919081
 B7=1.08919663
 B8=1.08645944
 B9=1.42844116       (1.4308)
 B10=1.17205304     (1.1579)
 A1=120.93839104
 A2=153.42773521
 A3=117.72738208
 A4=124.03498042
 A5=110.22699382
 A6=110.08854716
 A7=111.11756464
 A8=121.66765345
 A9=153.49356646
 D1=178.71968696
 D2=91.1613965
 D3=179.60620088
 D4=121.13540532
 D5=-120.1894336
 D6=0.36179315
 D7=90.02998216
 D8=179.87714224
  B1=1.08322114
 B2=1.3170981         (1.3136(
 B3=1.30624251       (1.3029)
 B4=1.08568138
 B5=1.50245982       (1.5012)
 B6=1.08990239
 B7=1.0898877
 B8=1.08708522
 B9=1.42854835       (1.4306)
 B10=1.1735203       (1.1579)
 A1=120.86139956
 A2=153.38348658
 A3=117.69166543
 A4=124.04403446
 A5=110.23913394
 A6=110.11223999
 A7=111.0206246
 A8=121.7547291
 A9=153.62165431
 D1=178.72599814
 D2=91.11172837
 D3=179.6888493
 D4=120.95617416
 D5=-120.32740181
 D6=0.21107373
 D7=90.11641155
 D8=179.8230946






















 



Table 3.  4-Methylcyanoallene.  Rotational Constants (MHz).  Calc (1) = MP2/6-311+G(3df,3pd) and Calc (2) =  MP2/aug-cc-pVTZ optimization, each with approximate re bond lengths.







Calc (1)
 Calc (2)
   Expt [1]






A 12644
 12677
 12732.907(15)

B   1587
   1586
   1576.05831(83)

C   1500
   1499
   1488.96638(81)


 








 








 








[1] S.Carles, H.Møllendal, Y.Trolez, and J.-C.Guillemin, A&A 564,A82(2014),

 








 








Cyanoallene





 








 








Table of Contents




Molecules/Nitrogen




 








 













CH3CHCCHCN.html






Last Modified 6 May 2014