Theoretical study of the electronic structure of diazomethane |
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Authors: | Lievin Jacques Verhaegen Georges |
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Institution: | (1) Laboratoire de Chimie Physique Moléculaire, Université Libre de Bruxelles, Faculté des Sciences, 50 avenue F. D. Roosevelt, B-1050 Bruxelles, Belgium |
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Abstract: | The least-energy dissociation path of the ground state of CH2N2 was determined fromab initio calculations using in a complementary way basis sets of minimal size (STO-3G) and double-zeta (DZ) quality. The results indicate that the least-energy point of attack of the N2 molecule on CH2 (1
A
1) is roughly perpendicular to the molecular plane (93 °), the C and N atoms being almost co-linear (angle C-N-N203 ° with outermost N atom pointing away from CH2). The potential barrier of 1.2 eV found previously on theC
2v
dissociation path, disappears completely along the least-energy dissociation path (point groupC
s
(out-of-plane)). These findings corroborate the Woodward-Hoffman rules for this process since the outermost orbitals of the two intersecting states found in point groupC
2v
(...2b
1 and ...8a
1) both correlate to the same irreducible representation (10á) in point groupC
s
(out-of-plane).Larger basis set calculations (DZ + polarization functions on all centers, 3d
c and 3d
N developed here), were also carried out on CH2N2 (1
A
1,3
A
2 and1
A
2) at the1
A
1 equilibrium geometry and on CH2 (3
B
1) and N2 (1
g
+
) at their respective equilibrium geometries. These calculations, together with consideration of correlation energy differences, yieldD
0
0
(CH2N2,1
A
1) = 19 kcal/mole and vertical excitation energies of 67 and 73 kcal/mole for the3
A
2 and1
A
2 states respectively. The latter value is in good agreement with the measured experimental value: 72.4 kcal/mole corresponding to the maximum of intensity in the1
A
21
A
1 absorption band. |
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Keywords: | Diazomethane electronic structure of " target="_blank">gif" alt="sim" align="MIDDLE" BORDER="0"> |
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