HCC-CH2CH2Br



































 









Bromine


Nuclear Quadrupole Coupling Constants


in gauche Bromobutyne


 








 

 





Complete nqcc tensors for both 79Br and 81Br in gauche bromobutyne were determined by Keske et al. [1].

 








Calculation of the nqcc tensors was made here on molecular structures derived by MP2/aug-cc-pVTZ optimization (ropt), and on this same structure but with corrected CBr, C-C, and triple CC bond lengths (~ re, see here).  These calculated nqcc's are compared with the experimental values in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants in Table 4.

 








In Tables 1 and 2, 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.  Ø (degrees) is the angle between its subscripted parameters.

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 for the B1LYP/TZV(3df,3p) model for calculation of the efg's/nqcc's.

 








  








   







Table 1.  79Br nqcc's in gauche HCC-CH2CH2Br (MHz).  Calculation was made on (1) the ropt structure, and (2) the ~ re structure.

 









Calc (1)
Calc (2)
Expt. [1]
   







Xaa
  54.20
  59.04
  64.3368(61)

Xbb
162.17
158.69
153.169(6) *

Xcc - 216.37 - 217.73 - 217.506(6) *

Xab
390.80
392.76
390.214(65)

Xac **
138.08
138.51
 -
 138.87(28)

Xbc **
164.64
163.08
 -
 163.437(77)

 







RMS
7.85 (5.42 %)
4.42 (3.04 %)



RSD
1.58 (0.39 %)
1.58 (0.39 %)



 







Xxx - 287.60  - 288.23 - 286.54

Xyy - 274.39 - 275.14 - 274.02

Xzz
561.99
563.37
560.57

ETA -
 0.0235 -
 0.0232



Øz,CBr







 







   








* Calculated here from experimental Xaa = 64.3368(61) and (Xbb -  Xcc) = 370.675(11) MHz using Kisiel's QDIAG.f.  See http://info.ifpan.edu.pl/~kisiel/prospe.htm

** Difference in algebraic sign between calc and expt is not significant.  In each case, the algebraic sign of the product XabXacXbc  is positive.

 


















   







Table 2.  81Br nqcc's in gauche HCC-CH2CH2Br (MHz).  Calculation was made on (1) the ropt structure, and (2) the ~ re structure.

 









Calc (1)
Calc (2)
Expt. [1]
   







Xaa
  46.76
  50.80
  55.0768(82)

Xbb
134.14
131.24
126.705(7)

Xcc - 180.90 - 182.04 - 181.782(7)

Xab
326.76
328.38
326.314(53)

Xac **
115.52
115.88
 -
 115.93(20)

Xbc **
137.13
135.84
 -
 135.496(75)

 







RMS
6.46 (5.33 %)
3.60 (2.97 %)



RSD
1.38 (0.40 %)
1.38 (0.40 %)



 








 








* Calculated here from experimental Xaa = 55.0768(82) and (Xbb -  Xcc) = 308.487(11) MHz using Kisiel's QDIAG.f.  See http://info.ifpan.edu.pl/~kisiel/prospe.htm

** Difference in algebraic sign between calc and expt is not significant.  In each case, the algebraic sign of the product XabXacXbc  is positive.

 












Table 3.  gauche HCC-CH2CH2Br.  Molecular structure parameters, ropt = MP2/aug-cc-pVTZ, approximate equilibrium bond lengths (~ re) are given in parentheses (Å and degrees).
 



 H
 C,1,B1
 C,2,B2,1,A1
 Br,2,B3,1,A2,3,D1,0
 H,2,B4,1,A3,3,D2,0
 H,3,B5,2,A4,1,D3,0
 H,3,B6,2,A5,1,D4,0
 C,3,B7,2,A6,1,D5,0
 C,8,B8,3,A7,1,D6,0
 H,9,B9,8,A8,1,D7,0






 B1=1.08594755
 B2=1.52069954       (1.5141)
 B3=1.92991679       (1.9380)
 B4=1.0858269
 B5=1.09101138
 B6=1.09360482
 B7=1.45734087        (1.4517)
 B8=1.21537495        (1.2044)
 B9=1.06191057
 A1=110.97657022
 A2=106.32823843
 A3=110.04186464
 A4=109.46283598
 A5=107.96505092
 A6=112.6170906
 A7=178.68262553
 A8=179.34572632
 D1=-121.21301621
 D2=123.88999685
 D3=-61.19766639
 D4=55.40179118
 D5=176.2261373
 D6=-39.13791564
 D7=100.27213826

 




 








 













Table 4.  gauche HCC-CH2CH2Br.  Rotational constants (MHz).  79Br species.
 



 
 ropt  ~ re    Expt. [1]






A 6818.
  6840.
 6880.1243(24)

B 1694.
  1699.
 1651.54449(40)

C 1427.
  1431.
 1398.48178(41)


 








 








[1] J.C.Keske, F.S.Rees, R.D.Suenram, and B.H.Pate, PCCP 5,1599(2003).

 








 








trans-HCC-CH2CH2Br HCC-CH2Br



 








 








Table of Contents




Molecules/Bromine




 








 













HCCCH2CH2Br_gau.html






Last Modified 26 Dec 2016