NC4H4-C(=O)H




 





 

































Nitrogen


Nuclear Quadrupole Coupling Constants


in 1H-Pyrrole-2-carbaldehyde


 








 








 








Investigation of the microwave spectrum of 1H-pyrrole-2-carbaldehyde was undertaken by Marstokk and Møllendal [1].  Conformation, rotational constants, and dipole moments were determined.

 








Calculation of the 14N nqcc tensor was made here on molecular structures given by MP2/6-311+G(2d,2pd) and B3LYP/cc-pVTZ optimization.  These nqcc's are given in Table 1; structure parameters in Table 2; rotational constants and dipole moments in Table 3; and quartic centrifugal distortion constants in Table 4.

 








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.

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 1H-Pyrrole-2-carbaldehyde (MHz).  Calculation was made on molecular structures given by (1) MP2/6-311+G(2d,2pd) and (2) B3LYP/cc-pVTZ optimization.
   









Calc. (1)
Calc. (2)
Expt.
   







Xaa
1.237
1.226



Xbb
1.093
1.135



Xcc -
 2.330
 -
 2.361



Xab
0.036
0.039



 







RSD
0.030 (1.3 %)
0.030 (1.3 %)



 







Xxx
1.245
1.240



Xyy
1.085
1.120



Xzz * -
 2.330
 -
 2.361



ETA -
 0.0689
 -
 0.0508



 








 








* Z-principal axis lies along c-axis, which is perpendicular to the pyrrole plane.

 







 
 

Table 2.  1H-Pyrrole-2-carbaldehyde.  Molecular structure parameters, ropt (Å and degrees).
 

         ropt(1) = MP2/6-311+G(2d,2pd) optimization.
ropt(2) = B3LYP/cc-pVTZ optimization.
 


C
C,1,B1
C,2,B2,1,A1
C,3,B3,2,A2,1,0.
N,1,B4,2,A3,3,0.
H,5,B5,1,A4,2,180.
H,1,B6,5,A5,4,180.
H,2,B7,1,A6,5,180.
H,3,B8,2,A7,1,180.
C,4,B9,3,A8,2,180.
O,10,B10,4,A9,3,180.
H,10,B11,4,A10,3,0.




       ropt(1)        ropt(2)




 B1=1.3927663
 B2=1.40880903
 B3=1.39790811
 B4=1.36217919
 B5=1.00740013
 B6=1.07506589
 B7=1.07537093
 B8=1.07656017
 B9=1.44588829
 B10=1.22851444
 B11=1.10045947
 A1=107.40561192
 A2=107.18899359
 A3=107.81863081
 A4=127.37040666
 A5=121.40554038
 A6=125.33870541
 A7=127.5334206
 A8=131.67040821
 A9=123.37204536
 A10=115.46285261
  B1=1.38463975
 B2=1.40721806
 B3=1.38850748
 B4=1.3547158
 B5=1.00638598
 B6=1.07626157
 B7=1.07615953
 B8=1.07708862
 B9=1.44236095
 B10=1.21831245
 B11=1.10552711
 A1=107.16570306
 A2=107.50348021
 A3=108.23403554
 A4=127.52279658
 A5=121.48258754
 A6=125.66784697
 A7=127.11839585
 A8=131.67891889
 A9=123.80281391
 A10=114.93095464





ropt(1) ropt(2)  Expt [1]






|as| O
 2.4833
 2.4793
 2.4755(5)

|bs| O
 0.3557
 0.3534
 0.3583(35)

|as| H(6) 0.3148
 0.2970
 0.3090(67)

|bs| H(6)
 1.7792
 1.7879
 1.7820(11)

 rs(H - - - O)
 2.5940
 2.6116
 2.592(6)




 








 














Table 3.  1H-Pyrrole-2-carbaldehyde.  Rotational Constants (MHz) and Dipole Moments * (D).







ropt(1) = MP2/6-311+G(2d,2pd) optimization.

ropt(2) = B3LYP/cc-pVTZ optimization.








ropt(1) ropt(2) Expt [1]







A
 7893.5
 7949.3
 7890.35(44)

B
 2081.6
 2088.5
 2085.040(5)

C
 1647.2
 1654.0
 1649.363(5)







|µa| 2.96
 2.94
 2.47(2)

|µb| 0.03
 0.07
 0.16(6)







* B3PW91/6-311+G(df,pd) calculation on ropt structures.






























Table 4.  1H-Pyrrole-2-carbaldehyde.  B3LYP/cc-pVTZ Quartic Centrifugal Distortion Constants (kHz).








Delta_J
0.162
 D_J
0.148

Delta_JK0.581
 D_JK
0.666

Delta_K 1.375
 D_K
1.304

delta_j 0.0387
 d_1
 -
 0.0387

delta_k 0.800
 d_2
 -
 0.00715









 







 








[1] K.-M.Marstokk and H.Møllendal, J.Mol.Struct. 23,93(1974).

 








 








Pyrrole
N-Methylpyrrole
 Imidazole
 Pyrazole

 








 








Table of Contents




Molecules/Nitrogen




 








 













2CHOPyrrole.html






Last Modified 5 Dec 2013