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HCC-CH2Br
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Bromine |
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Nuclear
Quadrupole Coupling Constants |
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in Propargyl Bromide |
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Bromine nqcc's in propargyl bromide were determined by Duffy et al. [1]. |
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Calculation of the nqcc's was made here on molecular structures derived by MP2/aug-cc-pVTZ(G03) optimization (ropt), and on this optimized structure but with corrected CBr, C-C, and triple CC bond lengths (~ re, see here). These 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. |
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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. The
nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular
to the molecular symmetry plane. Ø (degrees) is the angle between its subscripted
parameters. ETA = (Xxx - Xyy)/Xzz. |
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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 nqcc's. |
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Table 1. 79Br nqcc's in HCC-CH2Br (MHz). Calculation was made on (1) the ropt structure, and (2) the ~ re structure. |
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Calc (1)
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Calc (2) |
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Expt. [1] |
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Xaa |
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320.50 |
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323.26 |
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320.82(90) |
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Xbb |
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- 19.29 |
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- 21.35 |
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- 19.78 |
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Xcc |
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301.21 |
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301.90 |
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301.04(45) |
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|Xab| |
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415.25 |
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415.54 |
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415.95(32) |
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RMS |
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0.35 (0.16 %) |
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1.75 (0.82 %) |
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RSD |
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1.58 (0.39 %) |
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1.58 (0.39 %) |
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Xxx |
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298.06 |
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298.90 |
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298.95(42) |
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Xyy |
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301.21 |
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301.90 |
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301.04(45) |
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Xzz |
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599.27 |
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600.80 |
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599.99(42) |
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ETA |
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0.0052 |
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0.0050 |
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0.003 |
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Øz,a |
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33.87 |
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33.74 |
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33.87 |
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Øa,CBr |
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34.27 |
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34.12 |
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Øz,CBr |
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0.40 |
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0.38 |
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Table 2. 81Br nqcc's in HCC-CH2Br (MHz). Calculation was made on (1) the ropt structure, and (2) the ~ re structure. |
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Calc (1)
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Calc (2) |
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Expt. [1] |
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Xaa |
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268.47 |
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270.77 |
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269.45(95) |
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Xbb |
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- 16.82 |
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- 18.54 |
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- 17.68 |
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Xcc |
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251.65 |
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252.23 |
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251.77(48) |
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|Xab| |
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346.64 |
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346.88 |
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346.52(65) |
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RMS |
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0.75 (0.42 %) |
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0.95 (0.53 %) |
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RSD |
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1.38 (0.40 %) |
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1.38 (0.40 %) |
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| Table 3. HCC-CH2Br. Molecular structure parameters, ropt and ~ re (Å and degrees). These structures are given here in Z-matrix format. |
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ropt |
~ re |
| image to enlarge. |
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BrC(2) |
1.9425 |
1.9505 |
| C(2)H(6,7) |
1.0860 |
1.0860 |
| C(2)C(3) |
1.4458 |
1.4471 |
| C(3)C(4) |
1.2151 |
1.2043 |
| C(4)H |
1.0618 |
1.0618 |
| BrC(2)C(3) |
111.30 |
111.30 |
| CCCH Angles are |
C(2)C(3)C(4) |
179.44 |
179.44 |
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C(3)C(4)H |
179.83 |
179.83 |
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C(3)C(2)H(6,7) |
111.65 |
111.65 |
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H(6)C(2)H(7) |
109.78 |
109.78 |
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| Table 4. HCC-CH2Br. Rotational constants (MHz). 79Br species. |
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ropt |
~ re |
Expt. [1] |
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A |
21 022.4 |
21 008.7 |
21 010.306(12) |
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B |
2 184.1 |
2 178.6 |
2 169.3287(10) |
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C |
2 003.5 |
1 998.8 |
1 989.0591(11) |
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[1] P.K.J.Duffy, C.Hwang, D.T.Cramb, W.Lewis-Bevan, and M.C.L.Gerry, J.Mol.Spectrosc. 127,549(1988). |
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Y.Kikuchi, E.Hirota, and Y.Morino, Bull.Chem.Soc.Jpn. 34,348(1961): Xaa = 316, Xbb = -16, and Xab = 403 MHz.
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HCC-CH2Cl |
HCC-CH2I |
HCC-CH2CN |
CH3Br |
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Table of Contents |
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Molecules/Bromine |
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HCCCH2Br.html |
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Last
Modified 2 March 2008 |
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