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CF3(CF2)2CF2CN
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Nitrogen |
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Nuclear
Quadrupole Coupling Constants |
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in n-Perfluorobutyl
Cyanide transoid
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Calculation of the nitrogen nqcc's in n-perfluorobutyl cyanide, transoid was made on structures
given by
B3P86/6-31G(2d) optimization (ropt), and on this same
structure but with empirically derived
equilibrium CF, C-C, and CN bond lengths
(~ re).
These calculated nqcc's are given in Table 1. Structure
parameters are
given in
Table 2, rotational constants and electric dipole moments in Table 3. |
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In Table 1,
subscripts a,b,c refer to
principal axes of the inertia tensor; subscripts x,y,z to principal
axes
of the nqcc tensor. Øz,CN (degrees) is the
angle between the principal z-axis of the nqcc tensor and the CN bond
axis. ETA = (Xxx - Xyy)/Xzz. |
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RSD is the calibration residual
standard deviation of
the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen nqcc's,
which may be taken as an estimate of the uncertainty in the calculated
nqcc's (unertainties in the structures not-with-standing). |
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Table 1. 14N nqcc's in n-perfluorobutyl
cyanide, transoid (MHz).
Calculation was made on ropt and ~ re structures
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ropt |
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~ re |
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Expt. |
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Xaa |
- |
1.991 |
- |
1.988 |
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Xbb |
- |
0.295 |
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0.295 |
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Xcc |
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2.286 |
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2.282 |
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|Xab| |
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3.453 * |
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3.445 * |
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|Xac| |
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0.480 |
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0.477 |
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|Xbc| |
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0.427 |
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0.426 |
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RSD |
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0.030 (1.3 %) |
0.030 (1.3 %) |
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Xxx |
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2.326 |
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2.321 |
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Xyy |
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2.432 |
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2.426 |
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Xzz |
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4.757 |
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4.747 |
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ETA |
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0.0222 |
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0.0221 |
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Øz,CN |
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0.44 |
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0.43 |
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* The algebraic sign of the product XabXacXbc is
negative. |
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| Table 2.
n-Perfluorobutyl Cyanide, transoid.
Selected structure parameters, ropt and ~
re (Å and degrees). Complete
structures are given here in
Z-matrix format. |
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ropt |
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~ re |
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| C(1)C(2) |
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1.5474 |
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1.5461 |
| C(2)C(3) |
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1.5486 |
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1.5473 |
| C(3)C(4) |
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1.5513 |
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1.5498 |
| C(4)C(5) |
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1.4789 |
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1.4806 |
| C(5)N |
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1.1534 |
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1.1544 |
| C(1)C(2)C(3) |
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113.82 |
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113.82 |
| C(2)C(3)C(4) |
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114.00 |
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114.00 |
| C(3)C(4)C(5) |
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110.08 |
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110.08 |
| C(4)C(5)N |
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179.39 |
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179.39 |
| C(1)C(2)C(3)C(4) |
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165.01 |
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165.01 |
| C(2)C(3)C(4)C(5) |
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169.47 |
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169.47 |
| C(3)C(4)C(5)N |
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48.70 |
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48.70 |
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| Table 3.
n-Perfluorobutyl Cyanide, transoid.
Rotational
Constants (MHz) and Dipole Moments (D). |
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ropt |
~ re |
Expt. |
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A |
1176.6 |
1171.6 |
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B |
447.8 |
447.6 |
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C |
424.4 |
424.4 |
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|µa| |
1.20 |
1.18 |
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|µb| |
0.75 |
0.74 |
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|µc| |
0.15 |
0.14 |
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Order of the energies of the several
conformers of n-perfluorobutyl cyanide is Etransoid(0)
< EGA(0.54) < EAA(0.92) < EAG(6.95
kJ/mol). These are energies calculated at the B3PW91/6-311+G(df)
level of theory on the B3P86/6-31G(2d) optimized structures. |
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The AA (all trans, Cs)
conformer, with one imaginary frequency, is a saddle point connecting
two lower energy minima [1]. It is not, itself, a local minimum. |
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[1] J.B.Foresman and AE.Frisch,
Exploring Chemistry with Electronic Structure Methods, 2nd ed.,
Gaussian, Inc. Pittsburgh, PA 1995-96. |
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n-Butyl
Cyanide AG |
n-Perfluorobutyl
Cyanide AG |
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n-Butyl
Cyanide GA |
n-Perfluorobutyl
Cyanide GA |
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n-Butyl
Cyanide AA |
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Table of Contents |
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Molecules/Nitrogen |
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C4F9CN_transoid.html |
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Last
Modified 3 June 2010 |
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