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(CH3)2-CH-CH2I
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Iodine
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Nuclear
Quadrupole Coupling Constants |
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in gauche Isobutyl Iodide |
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Calculation of the
iodine nqcc tensor in gauche isobutyl iodide was
made on a molecular structure obtained by MP2/6-311+G(2d,p)
optimization, and on this same structure but with empirically
corrected C-C and CH bond lengths (approximate re). These calculated nqcc's are compared with
the experimental values of Niide and Ohkoshi [1] in Table 1. Structure
parameters are given in Table 2,
rotational constants in Table 3. |
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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. Øz,CI (degrees)
is the angle the z-principal axis makes with the CI bond axis. ETA = (Xxx
- Xyy)/Xzz. |
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RMS is the root mean square
difference between calculated and experimental diagonal nqcc's (percent of the
average of the magnitudes of the experimental nqcc's). RSD is the residual standard deviation
of calibration of the B1LYP/6-311G(df,p) model for calculation of
the nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's. |
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Table
1. 127I nqcc's in g-(CH3)2-CH-CH2I
(MHz). |
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Calculation was made on the following structures: |
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ropt (1) = MP2/6-311+G(2d,p) optimization, and |
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ropt (2) = MP2/6-311+G(2d,p) optimization with empirically corrected C-C and CH bond lengths. |
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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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1382.3 |
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1381.6 |
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1371.1(38) |
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Xbb |
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601.7 |
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601.6 |
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590.8(42) |
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Xcc |
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780.6 |
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780.0 |
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780.3(56) |
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|Xab| |
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840.5 * |
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839.8 * |
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841.7(19) |
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|Xac| |
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495.0 |
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494.8 |
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|Xbc| |
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198.3 |
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198.1 |
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RMS |
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9.0 (0.99 %) |
8.7 (0.95 %) |
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RSD |
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15.2 (1.23 %) |
15.2 (1.23 %) |
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Xxx |
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882.1 |
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881.6 |
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Xyy |
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918.5 |
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917.9 |
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Xzz |
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1800.6 |
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1799.5 |
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ETA |
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0.0202 |
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0.0202 |
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Øz,CI |
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0.67 |
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0.68 |
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* The algebraic sign of the product XabXacXbc is negative. |
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| Table 2. g-(CH3)2-CH-CH2I. Heavy atom structure parameters
(Å and degrees). Complete structures are given here in Z-matrix format. |
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| ropt(1) = MP2/6-311+G(2d,p) optimization. |
| ropt(2) = MP2/6-311+G(2d,p)
optimization with MP2/6-311+G(d,p) corrected C-C bond lengths,
and MP2/6-31G(d,p) corrected CH bond lengths (approximate re). |
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ropt(1) |
ropt(2) |
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| C(3)I |
2.1455 |
2.1455 |
| C(2)C(3) |
1.5198 |
1.5176 |
| C(2)C(4) |
1.5245 |
1.5195 |
| C(2)C(5) |
1.5304 |
1.5256 |
| C(2)C(3)I |
114.22 |
114.22 |
| C(3)C(2)C(4) |
112.32 |
112.32 |
| Click on image to enlarge. |
C(3)C(2)C(5) |
108.01 |
108.01 |
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| Table 3. g-(CH3)2-CH-CH2I. Rotational Constants (MHz). |
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ropt(1) |
ropt(2) |
Expt. [1] |
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A |
7522.2 |
7561.6 |
7433.57(67) |
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B |
1093.4 |
1095.5 |
1088.9006(35) |
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C |
995.6 |
997.9 |
991.2657(35) |
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[1] Y.Niide and I.Ohkoshi, J.Mol.Spectrosc. 143,284(1990). |
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CH3CH2I |
CH3I |
CH3-CHI-CH3 |
g-CH2I-CH2F |
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Table of Contents |
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Molecules/Iodine |
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gCH32CHCH2I.html |
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Last
Modified 11 Dec 2008 |
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